Dissertations / Theses: 'Surgical aortic valve replacement'

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Alassar, Aiman. "Incidence and mechanisms of cerebral ischaemia following transcatheter aortic valve implantation compared with surgical aortic valve replacement." Thesis, St George's, University of London, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686423.

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Background The most likely mechanisms of neurological injury following transcatheter aortic valve implantation (TA VI) and aortic valve replacement (A VR) are cerebral embolisation and hypoperfusion. Primary aim was to compare the potential mechanisms of neurological injury following TA VI and A YR. Methods 127 consecutive high risk patients with severe aortic stenosis who underwent TA VI (n=85) or A VR (n=42) were studied. Transcranial Doppler (TCD), cerebral oximetry, diffusion-weighted MRI (DW -MRI) (before, 6 days and 3 months following procedure) and neurocognitive assessment before and at 3 months were perfonned. Results Neurological injury was not significantly different between TA VI and AVR at one (1.1 % vs. 2.2%, p=0.25) and three months (4.7% vs. 2.2%, p= 1). At 3 months, overall cognitive score was higher in A VR compared with TA VI when adjusted for baseline score; the estimated difference between groups was 0.63 (95% Cl 0.87 - 1.17; p=0.02). Cerebral embolic load was 212 (123-344) during A VR and 134 (76-244) during TAVI, (p=0.07). Cerebral oxygen de saturation during AVR (7.56 ± 2.16) was higher compared to TAVI (5.93 ± 2.47) (p<0.01). Ischemic lesions measured by DW-MRI occurred in 76% ofTAVI and 71% of AVR patients at 6 days (p=0.69) and 63% and 39% at 3 months (p= 0.11). No significant association was found between cerebral emboli, cerebral oxygen desaturation, brain ischemic lesions and general cognitive score. Copclusions At 3 months follow-up, overall cognitive score was higher in A VR compared to TA VI, adjusted for baseline score. However, there was no difference in cerebral embolic load, ischemic lesions and oxygen desaturation.

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Taniguchi, Tomohiko. "Initial Surgical VersusConservative Strategies in Patients With Asymptomatic Severe Aortic Stenosis." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225456.

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Fairbairn, Tim. "Severe aortic valve stenosis and the consequences of transcatheter and surgical aortic valve replacement : a cardiovascular magnetic resonance study." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5853/.

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Background: Severe symptomatic aortic stenosis (AS) heralds a poor prognostic outlook and significant co-morbidity, with valve replacement the only definitive cure. Transcatheter aortic valve implantation (TAVI) has developed as an alternative to the standard treatment of surgical aortic valve replacement (SAVR) in high-risk or inoperable AS patients. The clinical and cost effectiveness of TAVI compared to SAVR requires further investigation. Methods: A prospective study of sixty seven TAVI and twenty seven SAVR patients, recruited from September 2009 to September 2011. Baseline assessments included a cerebral and cardiovascular magnetic resonance scan (1.5 Tesla MRI system) and the completion of two health surveys (EQ 5D and SF 12). Follow-up MRI was performed at 5±2 days (cerebral MRI) and 6 months (cardiovascular MRI) post AVR. Health status was assessed at 30 days, 6 months and one year. A cost-effectiveness analysis was performed using a 10 year Markov model with deterministic and probabilistic sensitivity analyses. Results: TAVI and SAVR resulted in similar levels of ventricular reverse remodelling. TAVI had a greater reduction in valvular impedance (21±8mmHg vs. 35±13mmHg, p=0.017) and myocardial fibrosis (10.9±6 % vs. 8.5±5%, p=0.03). Cerebral emboli occurred in 77% of TAVI patients. Age (r=0.37, p=0.042), severity of atheroma (r=0.91, p<0.001) and catheterisation time (r=0.45, p=0.02) were predictors of cerebral infarcts. HRQOL significantly improved over 12 months (PCS, p=0.02; EQ-5D, p=0.02; VAS, p=0.01 and SF6D p=0.03). Male gender (SF6D, p=0.01) and increased operator experience (PCS, EQ5D and VAS, p<0.05) predicted an improvement in HRQOL. Despite greater procedural costs, TAVI was cost-effective compared to SAVR over the 10 year model horizon (costs £52,593 vs. £53,943 and QALYs 2.81 vs. 2.75) indicating that TAVI dominated SAVR. Conclusions: TAVI has comparable cardiac and health benefits to SAVR, but greater cerebral complications. TAVI is likely to represent a clinical and cost effective alternative to SAVR.

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Musa, Tarique Al. "Transcatheter and surgical aortic valve replacement for severe aortic stenosis : insights from cardiovascular magnetic resonance imaging." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15238/.

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Background: Surgical aortic valve replacement (SAVR) remains first-line treatment for symptomatic severe aortic stenosis, whereas transcatheter aortic valve implantation (TAVI) is indicated in patients who are inoperable or considered too high-risk for surgery. Current focus is centred on differences in the impact of valve replacement upon cardiovascular function to guide patient selection and the development of novel prosthetic valves to improve outcomes. Cardiovascular Magnetic Resonance (CMR) imaging is the investigative modality of choice for such a purpose. Objectives: To compare the impact of SAVR and TAVI upon aortic stiffness, right ventricular function and myocardial strain, and to compare two vendor designs in the quantity of post-TAVI aortic regurgitation and reverse remodelling. Methods: A prospective study of patients with severe aortic stenosis under surveillance and subsequently requiring SAVR or TAVI, recruited between September 2009 and December 2015. A 1.5 Tesla CMR study was performed pre and 6 months post SAVR, and pre, immediately and 6 months post implantation of Medtronic CoreValve and Boston Lotus TAVI. Aortic distensibility (AD), pulse wave velocity (PWV), right ventricular (RV) volumes, myocardial strain and aortic regurgitation (AR) were quantified. Results: At 6 months, SAVR was associated with a significant worsening in PWV (6.38±4.47 vs. 11.01±5.75ms-1, p=0.001) and ascending AD (1.95±1.15 vs. 1.57±0.68x10-3mmHg-1, p=0.044), whereas no change was seen following TAVI. A significant reduction in RV ejection fraction (58±8 vs. 53±8%, p=0.005) was seen flowing SAVR, with no change following TAVI. A significant and comparable decline in LV torsion and twist was observed. Baseline circumferential strain was significantly associated with all-cause mortality (hazard ratio, 1.03; 1.01–1.05; p=0.009). Significantly less AR was seen immediately following Lotus than CoreValve TAVI (4.3±3.4 vs.11.7±8.4%, p=0.001) with equivalent degrees of reverse remodelling observed at 6 months. Conclusion: Compared with TAVI, SAVR is more detrimental upon aortic stiffness and right ventricular function at 6 months. CMR derived circumferential strain is associated with survival following SAVR and TAVI.

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Elsmaan, Mamdouh Aly Mohammed [Verfasser], and Andreas [Akademischer Betreuer] Zirlik. "Transcatheter and surgical aortic valve replacement in patients with previous coronary bypass grafts." Freiburg : Universität, 2017. http://d-nb.info/1134968086/34.

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Silaschi, Miriam Christine [Verfasser], and Hermann [Akademischer Betreuer] Reichenspurner. "Transcatheter aortic valve implantation versus surgical aortic valve replacement : a propensity score analysis in patients at high surgical risk / Miriam Christine Silaschi. Betreuer: Hermann Reichenspurner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1048626458/34.

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Ding, Wenhong. "Survival and functional recovery following valve replacement in patients with severe aortic stenosis." Doctoral thesis, Umeå universitet, Medicin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-82644.

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Background: Aortic stenosis (AS) is the most common heart valve disease in Europe and North America. Age-related calcification of the valve is the commonest cause of acquired AS, especially in patients older than 70 years.Conventional surgical aortic valve replacement (SAVR) and the novel, minimally invasive transcatheter aortic valve implantation (TAVI), effectively preserve left ventricular (LV) function, relieve symptoms and improve survival in patients with severe symptomatic AS. However, patients with impaired LV function may carry significant operative risk, and long recovery time. In addition, such patients might have other comorbidities, and hence adding another challenge. Thus evaluation of ventricular function before and after AVR, as well as critical evaluation of TAVI patients should contribute to better clinical outcome. Methods: We studied LV function by conventional echocardiography before and after SAVR in the following groups; (I) 86 patients (aged 71±10 years) with severe AS and LV dysfunction; (II) 112 consecutive elderly AS patients (aged 77±2 years) and compared them with 72 younger patients (aged 60±1 years); (III)66 patients (age 70±2 years, 53 male) who underwent AVR for severe AS with concurrent LV dysfunction; (IV) 89 consecutive patients with symptomatic severeAS who underwent successful TAVI, 45 of whom received trans-apical TAVI (TA)(age 80.8±4.9 year, 26 male) and 44 trans-femoral TAVI (TF) (age 82.9±5.8 year,22 male).The conventional echocardiographic measurements were made according to the guidelines. Severe AS was identified by aortic valve mean pressure gradient >40mmHg or valve area <1.0 cm2. LV systolic dysfunction was identified as ejection fraction (EF) <50%. LV long-axis function was presented by mitral annular plane systolic excursion ( MAPSE ) at lateral wall and septal wall, which were measured from apical four-chamber view. Also from the same view, LV septal and lateral wall deformation using STE as well as global longitudinal systolic strain. The LV systolic twist as the net difference between apical rotation and basal rotation was measured from the parasternal apical and basal short-axis views in the TAVI patients. Results: Study I: In the low flow and high gradient group, operative (30-day) mortality was 10%, and peri-operative mortality was associated with lower mean LVEF, higher mitral E:A ratio, peak systolic pulmonary artery pressure (PSPAP), and higher serum creatinine (all p<0.001), NYHA class III–IV, concomitant coronary artery bypass graft (CABG), urgent surgery, and longer bypass-time (all p< 0.05). Mortality at 4 years was 17%. Univariate predictors of 4-year mortality were: lower EF (p<0.001), presence of restrictive LV filling (p<0.001), raised PSPAP (p<0.001) and CABG (p=0.037). However, only EF<40 % (p=0.03), the presence of restrictive LV filling (p=0.033) and raised PSPAP (p<0.01)independently predicted mortality in this group.Study II: Elderly patients had higher NYHA class, more frequent atrial fibrillation (AF), coronary artery disease (CAD), emergency operation and use of bioprosthetic valves. They also had shorter E-wave deceleration time (DT) and larger left atria (LA) (p<0.05 for all). 30-day mortality was 12% vs 4 % (Log Rank x2=3.02, p=0.08) and long term mortality was 18% vs 7% (Log Rank x2=4.38,p=0.04) in the two groups, respectively. Age was not related to mortality after adjustment for other variables. Among all variables, anemia (OR 4.20, CI:1.02–6.86, p=0.04), cardiopulmonary bypass (CPB) time (OR 1.02, CI 1.01–1.04,p<0.01), significant patient prosthesis mismatch (PPM) (OR 5.43, CI 1.04–18.40,p<0.05) were associated with 30-day mortality in elderly patients. Their long-term mortality was related to CBP time (OR 1.02, CI 1.00–1.05, p=0.04),PPM (OR 4.64, CI 1.33–16.11, p=0.02) and raised LA pressure: DT (OR 0.94, CI0.84–0.99, p=0.03) and pulmonary artery systolic pressure (PASP) (OR 1.12, CI1.03–1.19, p<0.001).STUDY III: Following SAVR peak aortic pressure gradient (AOPG) decreased and indexed valve area increased (64±3 to 19±1 mmHg and 0.30±0.01 to 0.89±0.03 cm2/m2, p<0.001 for both). LVEF increased (from 45±1 to 54±2%;p<0.001), LV end diastolic and end-systolic dimensions fell (LVEDD index: from 33±1 to 30±1 mm/m2; and LVESD index: from 27±1 to 20±1 mm/m2; (p<0.01 forboth). LV diastolic dysfunction improved as evidenced by the fall in E/A ratio (from 2.6±0.2 to 1.9±0.4) and prolongation of total filling time; (from 29.2±0.6 to31.4±0.5 s/min, p=0.01 for both). Among all echocardiographic variables, LV dimensions (LVEDD index, OR 0.70, CI 0.52–0.97, p<0.05; LVESD index, OR 0.57, CI 0.40–0.85, p=0.005) were the two independent predictors of post-operative LV functional recovery on multivariate analysis. A cut-off value ofpre-operative LVESD index<=27.5 mm/m2 was 85% sensitive and 72% specific inpredicting intermediate-term recovery of LV function after AVR (AUC, 0.72, p=0.002). STUDY IV: Before TAVI, there was no difference between the two patient groups in gender, age, body surface area (BSA) and baseline LV function. However, left ventricular mass index (LVMi), left atrial volume index (LAVi) and tricuspid regurgitation pressure drop (TRPdrop) were increased in the TA group (p<0.05).One week after TAVI, aortic pressure gradient (AOPG) markedly dropped in thetwo groups (both p<0.001), LVEDD index and LVESD index fell but EF andmyocardial strain remained unchanged. Overall cavity twist reduced (p<0.048).Significant LVESD index reduction was only seen in TF group (p=0.02) with a slight increase in LVEF (p=0.04). Lateral MAPSE increased only in the TF group(p=0.02). LV longitudinal systolic strain remained unchanged in TA patients while apical lateral strain increased in TF group. LV apical rotation fell in the two groups but basal rotation increased only in the TA patients (p=0.02). LAVi reduced in bothgroups and to a greater extent in TF TAVI (p=0.006), as did TRPdrop (p<0.001). Conclusion: SAVR and TAVI are two effective treatments for severe AS patients.The severity of pre-operative systolic and diastolic LV dysfunction is the major predictor of mortality following SAVR for low-flow and high gradient AS.Peri-operative AVR survival is encouraging in the elderly. Long term mortality in the elderly is related to PPM, LV diastolic dysfunction and secondary pulmonary hypertension. LV functional recovery was evident in most patients with LV dysfunction after SAVR. A lower prevalence of LV functional recovery in patients with large pre-operative LVESD index might signify the loss of contractile reserveand thus predict post-operative functional recovery. TAVI results in significant early improvement of segmental and overall ventricular function, particularly in patients receiving the trans-femoral approach. The delayed recovery of the trans-apical TAVI group, we studied, might reflect worse pre-procedural diastolic cavity function.

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Dobson, Laura Elizabeth. "Cardiovascular magnetic resonance imaging in severe aortic stenosis : impact of surgical and trans-catheter aortic valve replacement on reverse remodelling and fibrosis." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/12944/.

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Introduction: Aortic stenosis (AS) is the commonest valvular lesion in the developed world and is associated with adverse cardiac remodelling. With its excellent accuracy and reproducibility, cardiovascular magnetic resonance (CMR) imaging is an ideal tool to assess cardiac remodelling and reverse remodelling following surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI). The aims of this thesis were: 1) to evaluate gender differences in AS and following aortic valve replacement, 2) to evaluate the incidence of post-procedural myocardial infarction following SAVR and TAVI, 3) to describe the immediate effect of TAVI on reverse remodelling and 4) to assess the impact of TAVI-induced left bundle branch block (LBBB) . Methods: Between January 2009 and April 2015, patients with severe AS undergoing either TAVI or SAVR were prospectively recruited. Patients underwent comprehensive 1.5T CMR evaluation pre-procedure, prior to hospital discharge and 6m post-procedure. Results: 1) Women with severe AS have a lower indexed left ventricular (LV) mass than men (65.3± 18.4 vs. 81.5±21.3g/m2, p < 0.001). 6m following valve replacement, LV mass regression is similar between genders (men 21.7±10.1 vs. women 18.4±11.0%, p=0.121). 2) Myocardial infarction (MI) is more frequent following SAVR than TAVI (n=10 (26%) vs. n=3 (5%), p=0.004). 3) Over 10% of LV mass regression occurs prior to hospital discharge following TAVI and is more pronounced in the absence of myocardial fibrosis (p=0.005). 4) TAVI-induced LBBB is associated with a reduced LVEF 6m following TAVI compared with those with a narrow QRS (-2.1±6.9 vs. +4.6±7.8%, p=0.002). Conclusions: TAVI and SAVR are associated with favourable cardiac reverse remodelling which does not differ according to gender and begins prior to hospital discharge. SAVR is associated with a higher incidence of post-procedural MI than TAVI. TAVI-induced LBBB should be avoided where possible due to its unfavourable effects on cardiac reverse remodelling.

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Uddin, Akhlaque. "Magnetic resonance imaging in the assessment of surgical and transcatheter aortic valve replacement : the impact on neurocognitive function and myocardial reverse remodelling." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16299/.

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Background: Aortic valve stenosis is the most common degenerative valve disease affecting the Western elderly population. Medical therapy is ineffective at treating the mechanical obstruction of blood flow. Surgical Aortic Valve Replacement (SAVR) is the current recommended treatment for symptomatic severe AS but often high risk patients are declined for this. Transcatheter Aortic Valve Implantation (TAVI) allows the percutaneous delivery of the prosthetic valve but this novel approach is associated with complications. Aims: This thesis aims to focus on the effects of TAVI and contemporary SAVR on patients’ quality of life, neurocognitive function and the left ventricular reverse remodelling. Methods: High risk patients with symptomatic aortic stenosis were studied at baseline, 30 days, 6 month and 12 months after intervention. Cerebral MRI with diffusion weighted imaging for micro-embolism was conducted before and after intervention and again at 6 months. Cardiac MR was conducted at baseline and 6 months. Health related quality of life and a comprehensive battery of neurocognitive functional assessments were also conducted across 3 and 4 time points respectively. Results: The incidence (54(77%) vs. 17(43%), p=0.001) and number (3.4±4.9 vs. 1.2±1.8, p=0.001) of new micro-infarcts was greater after TAVI compared to SAVR. Physical component scores (PCS) in TAVI increased after 30 days (32.1±6.6 vs. 38.9±7.0, p<0.0001) and 6m (40.4±9.3, p<0.0001); the improvement occurred later in SAVR (baseline: 34.9±10.6, 30d: 35.9±10.2, 6m: 42.8±11.2, p<0.001). At 12 months, the majority of neurocognitive function tests did not show a significant change in the proportion of patients categorised as having impaired NCF compared to baseline in the TAVI or SAVR groups. After 6 months, there were significant improvements in indexed end-diastolic volumes (TAVI: 100±25mls vs. 87±26mls, p<0.001; SAVR 91±28mls vs. 82±17mls, p<0.05) Extracellular volumes were similar for both groups at baseline (range 22.8 to 24.6%). There was no significant change in ECV after 6 months (TAVI, 24.0±9% vs. 29.3±11%, SAVR, 23.8±7 vs. 23.5±9, p= 0.76). Conclusions: TAVI patients experience higher numbers of cerebral micro-infarcts than contemporary SAVR patients, but this appears to have no effect on HRQoL; TAVI patients experienced earlier improvements in quality of life than SAVR patients. There was also no evidence of neurocognitive functional decline after TAVI using a battery of very sensitive neurocognitive function tests. Both TAVI and SAVR improved cardiac imaging parameters with evidence of reverse LV remodelling but no change in diffuse myocardial fibrosis after 6 months.

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Cardone, Letizia [Verfasser], Payam [Gutachter] Akhyari, and Timo [Gutachter] Brandenburger. "Evaluation of circulating exosomes in the course of surgical aortic valve replacement and coronary artery bypass grafting / Letizia Cardone ; Gutachter: Payam Akhyari, Timo Brandenburger." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2021. http://d-nb.info/1233478222/34.

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Joyce, Ruth Ann. "Quality of life and cerebral ischaemia following aortic valve replacement and transcatheter aortic valve replacement." Thesis, St George's, University of London, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706528.

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Background Aortic valve replacement (AVR) has been associated with postoperative transient ischaemic attack, stroke and neurocognitive decline. Transcatheter aortic valve implantation (TAVI) has been in development for nearly a decade for patients not suitable for surgery. Cognitive change after TAVI is not yet clear. We set out to examine the effects of cognitive dysfunction on quality of life (QoL) following TAVI and AVR. Methods 88 consecutive high risk patients with severe aortic stenosis and discussed at an MDT who underwent TAVI (n=38) or AVR (n=50) were studied. Transcranial Doppler ultrasound (TCD) examinations were recorded for all patients. A comprehensive neurocognitive assessment was performed on patients at baseline and 3 months using a battery of cognitive tests. QoL analysis was completed on patients at baseline, 3, 6 and 12 months using the Short Form 36 (SF-36v2™) with an additional propensity matched group analysed. Results Cerebral embolic load had a mean of 271 (range 160-309) in AVR patients and 280 (range 186- 326) in TAVI patients. Duration of cardiopulmonary bypass (CPB) for AVR and valve deployment for TAVI, were associated with the highest number of embolic signals (ES) recorded (mean 106 and 103 respectively). AVR and TAVI patients had a significant decrease in processing speed (p=0.04 and p=0.04). The AVR group showed a cognitive decline in visual planning and short term memory (p=0.02), TAVI patients in new learning and verbal memory (p=0.02, p=0.03). Both procedures resulted in an increase in patient QoL with no difference in improvements between AVR and TAVI patients in the propensity matched group. Conclusion ES load was recorded for AVR and TAVI, with significantly more ES for duration of bypass in AVR and deployment of the valve in TAVI. AVR and TAVI patients had mild post-operative cognitive changes with both having a significantly decreased processing speed score at 3 months follow up. QoL of patients undergoing AVR and TAVI increased post-procedure at 3, 6 and 12 months. Patients improved equally in terms of QoL in the propensity matched group of AVR and TAVI patients.

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Klieverik, Loes Maria Anne. "Aortic valve replacement in young adults." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10778.

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Nowell, Justin L. "Anticoagulation Following Tissue Aortic Valve Replacement." Thesis, St George's, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517184.

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Park, Kenneth Stuart. "Stents for transcatheter aortic valve replacement." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27372.

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Rheumatic heart disease (RHD) is the leading cause of aortic valve disease in the world. Surgery to repair or replace the diseased valves is the only means to save a patient's life once the disease becomes symptomatic. Transcatheter aortic valve replacement (TAVR) has revolutionised the treatment of age-related degenerative aortic valve disease, but is currently not suitable for the majority of RHD sufferers due to the rapid degeneration of flexible leaflet valves in younger patients, contraindications of commercial devices to regurgitant or non-calcific aortic valve disease, and also due to resource or funding limitations. The current research project aimed to develop and test novel compressible balloon-expandable stents suitable for patients with symptomatic rheumatic aortic valve disease, and which would allow for a percutaneous polymeric valve to be manufactured, be crimped onto balloon-based devices, and be expanded into a compliant or non-calcific native aortic valve. Several stent concepts were developed and evaluated using Finite Element Analysis (FEA) and two favoured concepts were selected for more complex FEA, in which the balloon was simulated using an Ogden material model, and rigorous testing. The stent material, a nickel-cobalt-chromium alloy, was modelled as an isotropic elasto-plastic material with isotropic hardening. The novel stent designs incorporated a native leaflet-mimicking crown shape for continuous leaflet attachment and mechanisms to anchor the stented valve within compliant aortic roots. The first of the favoured designs provided tactile location during delivery and anchored using self-expanding arms on a balloon-expandable frame of the same material ("self-locating stents"). The second design anchored using arms that protruded during deployment as a consequence of plastic deformation incurred during crimping ("expanding arm stents"). Prototypes were successfully manufactured through laser cutting and electropolishing and showed good surface quality. In vitro testing included determination of crimping and expansion behaviour and measurement of mechanical properties such as resistance to migration in the anatomy. Valve performance was evaluated through in vitro haemodynamics in a pulse duplicator and durability was tested in a high-cycle fatigue tester. Simulated use testing was performed using cadaveric animal hearts. Finally, valves were also implanted into the aortic valve position of pigs (in acute termination experiments) through a transapical approach in order to verify valve deployment behaviour and function in vivo, and determine the stent's ability to anchor in the native anatomy. Stents could be crimped to diameters below 6mm and deployed using commercial balloons and proprietary non-occlusive deployment devices. FEA simulations of stent crimping and deployment matched experimental behaviour well and provide a tool to optimise stent performance. Peak Von Mises stresses during deployment (1437 MPa and 1633 MPa for self-locating and expanding arm stents, respectively) were comparable to a "zig-zag" stent simulated for control purposes (1650 MPa). Radial strength, evaluated for expanding arm stents, was lower than the Control stent (116 N vs. 347 N). This design, although predicted to be safe under fatigue loading, had a lower fatigue safety factor than the Control stent. Stents resisted migration to forces of at least 22 N, which is four times greater than physiological loading on the valves. Polymeric valves incorporating the stents were constructed and demonstrated good in vitro haemodynamic performance (Effective Orifice Areas ≥2.0cm², ΔP<9 mmHg, regurgitation <6%) and durability of over 400 million cycles. Designs functioned as intended in simulated use tests. Valves constructed using self-locating stents could be successfully deployed without rapid pacing in eight of nine pigs, and valve position was correct in seven of these. Valves of expanding arm stents remained anchored in six of eight attempted implants in pigs. This study has demonstrated proof of concept for a novel balloon-expandable stent for a polymeric transcatheter heart valve that is capable of anchoring in a compliant native aortic valve.

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Hatoum, Hoda. "Fluid Mechanics of Transcatheter Aortic Valve Replacement." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1541781379381912.

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Nai, Fovino Luca. "Coronary access after transcatheter aortic valve replacement." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3424785.

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Coronary artery disease (CAD) and aortic stenosis (AS) often coexist. While the clinical impact of CAD on subjects with AS undergoing transcatheter aortic valve replacement (TAVR) is controversial, current guidelines suggest revascularization of proximal severe CAD before TAVR. This recommendation is mainly based on concerns about the possibility to reaccess the coronary arteries once the transcatheter heart valve (THV) is in place. In fact, previous case series report challenges in cannulation of coronary ostia after TAVR, particularly with self-expandable THVs. These aspects are important as indication to TAVR is moving towards younger patients, who are more likely to need CA, giving the progressive nature of CAD and their longer life expectancy. The first objective of our research was to assess the incidence of coronary access (CA) after TAVR at long-term follow up in a high-volume center, evaluating safety and feasibility of coronary angiography and percutaneous coronary intervention (PCI) after TAVR with different types of THVs. At a median follow up over 3 years, incidence of CA after TAVR was 5.3%. In one out of three patients, indication to CA was an acute coronary syndrome, and PCI was performed in over half of the cases. Independent predictors of CA after TAVR were younger age, previous PCI and CABG. CA of both vessels was feasible in all patients with an intra-annular THV, while the right coronary artery was not engaged in two patients with a supra-annular THV. PCI was successful in all but one case. All-cause mortality tended to be higher for patients needing CA for acute coronary syndrome. Secondly, we evaluated advantages and pitfalls of CA after TAVR in the presence of bicuspid aortic valve (BAV) stenosis. We performed post-TAVR 3-dimensional computed tomography in patients with BAV treated both with balloon-expanding and self-expandable THVs. In this particular anatomical setting, CA after TAVR as advantages and pitfalls. For instance, the potential asymmetrical prosthesis expansion when the rafe is located between the left and right coronary cusp generates a larger free space between the valve frame and the coronary ostia, thereby simplifying CA. On the contrary, the higher implantation of the THV in the setting of BAV represents a potential challenge for CA. Finally, we aimed to assess the feasibility of CA after TAVR-in-TAVR. In fact, as TAVR indication is moving towards patients with longer life expectancy, THV degeneration will be increasingly common. TAVR-in-TAVR is an appealing therapeutic option in this setting, but concerns have been raised about the risk of acute coronary obstruction and the possibility to re-access the coronaries once the second prosthesis is in place. In fact, when the second THV is implanted, the leaflets of the first prosthesis are displaced vertically, creating a cylindric cage which will impair CA and possibly coronary flow. Consequently, there is a risk plane under which the first valve frame will not be crossable after TAVR-in-TAVR. We therefore developed a novel, imaging-based algorithm to predict possible coronary access impairment after TAVR-in-TAVR, based on the way CA is gained after the index TAVR and on the distance between prosthesis frame and aortic wall under the level of the RP. We then tested our hypothesis by performing coronary angiography after TAVR in 137 consecutive patients. According to our algorithm, CA after TAVR-in-TAVR might be impaired in almost 1/3 of patients currently treated by TAVR. This risk appears to be less frequent with intra-annular SAPIEN 3 as compared to supra-annular Evolut R/Pro and Acurate Neo THVs. Implantation of a supra-annular device, female gender and small sino-tubular junction are independent predictors of possible CA impairment after TAVR-in-TAVR. These results, which will need to be validated in clinical practice, are important for patient counseling and prosthesis selection in subjects with longer life expectancy

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17

Lopez, Marco Ana. "Low-flow low-gradient aortic stenosis: outcomes after aortic valve replacement." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/667817.

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Aortic stenosis is the commonest valve disorder in the Western World. The natural history of the disease is very well described; with a decreased survival once symptoms occur. There is currently, no medical therapy available to reduce the natural progression of the aortic stenosis, and therefore, aortic valve replacement has been recognised as the standard of care treatment for symptomatic aortic stenosis, with TAVI having merged as alternative for those cases with high/prohibitive surgical risk. All types of aortic stenosis have in common a reduced valve area (AVA <1.0cm2), but depending on the mean gradients and the stroke volume index, there are different types: Normal-Flow High-Gradient (NFHG AS) and Low-Flow Low-Gradient (LFLG AS) aortic stenosis. The latter is further subdivided into Classical and Paradoxical forms depending on the ejection fraction value. NFHG AS is the most common type. The left ventricle is capable of generating a normal flow through the stenotic valve, that it is translated onto high gradients. This type has been thoroughly studied and has an excellent prognostic with aortic valve replacement, with very low in-hospital mortality and long-term survival similar to the age-matched population. LFLG AS, on the other hand, is defined by a reduced stroke volume (SVi < 35 ml/min) and a low gradient (mean gradient < 40mmHg). The Classical form (CLFLG AS) has impaired ventricular function. These patients have dilated ventricles that are not able to generate enough flow through the stenotic valve and hence the low gradient. Dobutamine stress echocardiography is key for the diagnosis of this subtype, as it differentiates it from the Pseudo-Severe aortic stenosis (in which the problem is not in the aortic valve but in the left ventricle, and therefore there is no benefit from aortic valve replacement) and it has also prognostic value by determining the contractile reserve. These patients have been reported to have the highest mortality post aortic valve replacement and a reduced long-term survival; however, those who survive achieve excellent functional class. The other subtype of LFLG, the Paradoxical form (PLFLG AS) has a preserved ventricular function. These patients have a ventricular restrictive physiology, with reduced SVi due to a combination of mechanism such as subendocardial fibrosis, concentric remodeling, impaired diastolic filling and high afterload. It is paramount here to confirm the diagnosis by accurate echocardiography, ruling out measurement errors and other causes of reduced SVi. PLFLG AS patients have worse prognosis than NFHG AS but better prognosis than CLFLG AS patients. The primary hypothesis of our research project was that aortic valve replacement could be performed in patients with LFLG AS with low in-hospital mortality. Therefore, with the objectives of determining operative and mid-term outcomes of surgical intervention in LFLG AS compared to NFHG AS, we conducted a retrospective analysis of all patients who underwent isolated aortic valve replacement in our centre. Primary end-points were mortality (in-hospital, at one and five years) and the secondary end-points analysed were postoperative complications and clinical status at follow-up. Patients in the LFLG AS group were significantly older and had more cardiovascular risk factors and comorbidities than the NFHG AS group. Despite those differences, in-hospital mortality was equivalent and remarkably low in both groups. As expected, LFLG AS patients had a reduced mid-term survival but those who survived remained in an excellent functional class. With the separate analysis of the LFLG AS subgroups, we confirmed that CLFLG AS had higher in-hospital and mid-term mortality than PLFLG AS patients. In both groups, the in-hospital mortality was remarkably low compared to previous literature reports. Aortic valve replacement provided symptomatic relief and excellent functional class during the mid-term follow-up as well as recovery of the ventricular function in most of the patients. Based on our results, we concluded that aortic valve replacement should be recommended for symptomatic severe LFLG AS. La estenosis aórtica es la enfermedad valvular más frecuente en el tercer mundo. La historia natural de la enfermedad es bien conocida desde hace décadas, siendo una enfermedad con mal pronóstico a medio-corto plazo que hace necesario someter a estos pacientes a recambio valvular aórtico tras la aparición de síntomas. La forma mas común de estenosis aórtica, con flujo normal y gradiente alto, tiene un pronóstico excelente tras el recambio valvular aórtico, con una supervivencia similar a la de la población normal. Sin embargo, la estenosis aórtica de bajo-flujo y bajo-gradiente, es una entidad menos conocida y de peor pronóstico. Estos pacientes tienen una mortalidad mucho mayor tras recambio valvular aórtico y menor supervivencia a largo plazo. El diagnóstico en el bajo-flujo bajo-gradiente es vital para seleccionar correctamente los pacientes con estenosis aórtica que se beneficiarán de tratamiento quirúrgico, teniendo también valor pronóstico, dependiendo de la categoría de bajo flujo (Clásica o Paradójica) y otros determinantes como la presencia/ausencia de reserva contráctil del ventrículo izquierdo. Nuestra hipótesis fue que la estenosis aórtica de bajo-flujo y bajo-gradiente, pueden ser tratada con recambio valvular aórtico con una mortalidad hospitalaria similar a aquellos con flujo normal y alto gradiente. Los objetivos del proyecto fueron el análisis de resultados hospitalarios y a medio plazo (mortalidad hospitalaria, a 1 y 5 años) así como la clase funcional y recuperación de la función ventricular, en pacientes con estenosis aórtica de bajo-flujo bajo-gradiente sometidos a recambio valvular aórtico comparado con flujo normal alto-gradiente. Nuestros resultados nos llevan a la conclusión de que el recambio valvular aórtico en pacientes con estenosis aórtica de bajo-flujo bajo-gradiente se puede lograr con baja mortalidad quirúrgica, comparable con pacientes con flujo normal y alto gradiente. A pesar de que tener una mayor mortalidad a medio-plazo, los supervivientes exhiben una excelente clase funcional y desaparición de síntomas, que apoyan la indicación quirúrgica en estos pacientes.

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Janicki, Andrew Joseph. "ANALYSIS OF PARTICLES THOROUGH THE AORTIC ARCH DURING TRANSCATHETER AORTIC VALVE REPLACEMENT." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1448.

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Ischemia caused by particles becoming dislodged during transcatheter aortic valve replacement (TAVR) is a possible complication of TAVR. The particles that become dislodged can travel out of the aortic valve, into the aortic arch, and then into either the brachiocephalic artery, the left common carotid artery, the left subclavian artery or continue into the descending aorta. If the particles continue into the descending aorta it poses no risk of causing ischemia however if it travels into the other arteries then it increases the possibility of the particle causing an ischemic event. The goal of this study is to determine what parameters cause the particle to enter one artery over another. The parameters analyzed are the particle diameter, the particle density, the blood pressure, and the diameter of the catheter used in the surgery. This was done by creating a finite element model in COMSOL Multiphysics® to track the particles flowing through a scan of an actual aortic arch. It was determined that the particle diameter, particle density, and the blood pressure affect which artery the particles take to exit the aortic arch. However the diameter of the surgical catheter used in a transaortic approach is not statistically significant when determining which artery the particles will exit. The study shows that larger diameter particle would lead to a higher transmissions probability into the brachiocephalic artery, the left common carotid artery, and the left subclavian artery while a smaller diameter particle would have a higher transmission probability for the descending aorta. Averaging all particle diameters, densities and blood pressure found that 54.95 ± 13.66% of the particles released will travel into the cerebral circulatory system.

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19

He, Zhengfu [Verfasser]. "Percutaneous Aortic Valve Replacement [[Elektronische Ressource]] ： The Anatomy of Aortic Root Structures and Postmortem Aortic Valve Stent Implantation / Zhengfu He." Kiel : Universitätsbibliothek Kiel, 2011. http://d-nb.info/1020200936/34.

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20

Rubino, A. S. (Antonino S. ). "Efficacy of the Perceval sutureless aortic valve bioprosthesis in the treatment of aortic valve stenosis." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212289.

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Abstract Aortic valve stenosis (AS) is one of the most diffuse valvular diseases in developed countries. AS is a progressive disease, which usually results in serious life-threatening adverse events. Defining a treatment strategy for AS is a focus of cardiovascular research, although the topic is still controversial because of its related clinical and economical implications. Surgical aortic valve replacement (AVR),which is regarded as the gold standard for the treatment of severe symptomatic AS, affords excellent results, particularly in asymptomatic patients with good functional status. AVR requires the institution of cardiopulmonary bypass and aortic cross-clamping, and the duration of these procedures is directly associated with increasing morbidity and mortality, especially in patients with preoperative comorbidities. Accordingly, techniques aimed at decreasing the duration of cardiopulmonary bypass and aortic cross-clamping have the potential to improve postoperative outcomes of AVR. In the present study, we demonstrated that the Perceval sutureless bioprosthesis could significantly reduce the duration of the surgical procedure. This was associated with improved immediate postoperative outcomes and long-term freedom from adverse events. The use of a Perceval sutureless bioprosthesis can facilitate AVR through minimally invasive approaches and is associated with fewer transfusions of packed red cells compared to full sternotomy approaches, even with traditional stented bioprostheses. It could be expected that patients at intermediate-high risk would benefit more from the combination of a fast surgical procedure, performed with reduced surgical invasiveness. When compared to transcatheter aortic valve implantation (TAVI), the Perceval sutureless bioprosthesis was associated with increased incidence of device success as well as less paravalvular leak, with similar immediate and 1-year outcomes. Finally, AVR with the Perceval sutureless bioprosthesis provided excellent hemodynamics at rest and under high workload. The significant increase of effective orifice area under stress suggests that the Perceval sutureless bioprosthesis is the valve of choice for patients with small aortic annuli or when prosthesis-patient mismatch is anticipated Tiivistelmä Aorttaläpän ahtauma on yksi yleisimmistä läppävioista kehittyneissä maissa. Aorttaläpän ahtauma on etenevä sairaus, joka yleensä johtaa vakaviin henkeä uhkaaviin haittatapahtumiin. Aorttaläpän ahtauman hoitotavasta keskustellaan kiivaasti sydän- ja verisuonitautien tutkimuksessa siihen liittyvien kliinisten ja taloudellisten vaikutusten vuoksi. Aorttaläppäleikkausta, jossa aorttaläppä korvataan proteesilla, on aina pidetty vaikean oireisen aorttaläpän ahtauman hoidon kultaisena standardina, koska sen tulokset ovat erinomaisia, etenkin oireettomilla potilailla, joilla sydämen toiminta on hyvä. Leikkaus vaatii sydän-keuhkokoneen käyttöä ja aortan sulkemista, joiden kesto on suoraan yhteydessä kasvavaan sairastavuuteen ja kuolleisuuteen erityisesti potilailla, joilla on muitakin sairauksia. Niinpä tekniikat, jotka lyhentävät sydän-keuhkokoneen käyttöaikaa ja aortan sulkuaikaa, voivat mahdollisesti parantaa aorttaläppäleikkauksen tuloksia. Tässä tutkimuksessa osoitettiin, että ompeleettoman biologisen Perceval-läppäproteesin käyttö vähensi merkittävästi leikkauksen kestoa. Tämä oli yhteydessä parantuneisiin lyhyen ja pitkän aikavälin tuloksiin leikkauksen jälkeen. Ompeleettoman biologisen Perceval-läppäproteesin käyttö voi helpottaa aorttaläppäleikkausta, koska se voidaan asentaa vähemmän kajoavasta avauksesta, ja siihen liittyy vähemmän punasolusiirtoja rintalastan kokoavaukseen verrattuna, myös silloin kun käytetään kokoavausta ja perinteisiä stenttibioproteeseja. Voisi olla odotettavaa, että keskisuuren tai suuren riskin potilaat hyötyisivät enemmän leikkauksesta, jossa yhdistyvät toimenpiteen nopeus ja vähäisempi kajoavuus. Katetriteitse asennettuun biologiseen keinoläppään (TAVI) verrattuna ompeleeton biologinen Perceval-läppäproteesi oli yhteydessä parempaan laitteen toimimiseen ja pienempään paravalvulaariseen vuotoon. Muut tulokset heti leikkauksen jälkeen ja yhden vuoden seurannassa olivat samanlaisia. Lopuksi voidaan todeta, että aorttaläppäleikkaukseen ompeleettomalla biologisella Perceval-läppäproteesilla liittyi erinomainen hemodynamiikka levossa ja korkean työkuorman aikana. Stressin aikaisen tehokkaan aorttaläpän aukon pinta-alan merkittävä kasvu osoittaa, että ompeleeton biologinen Perceval-läppäproteesi on hyvä valinta potilaille, joilla on pieni aorttaläpän aukko tai kun on odotettavissa proteesin ja potilaan yhteensopimattomuutta

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21

Zhao, Ying. "Effect of valve replacement for aortic stenosis on ventricular function." Doctoral thesis, Umeå universitet, Institutionen för folkhälsa och klinisk medicin, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-46809.

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Background：Aortic stenosis (AS) is the commonest valve disease in the West. Aortic valve replacement (AVR) remains the only available management for AS and results in improved symptoms and recovery of ventricular functions. In addition, it is well known that AVR results in disruption of LV function mainly in the form of reversal of septal motion as well as depression of right ventricular (RV) systolic function. The aim of this thesis was to study, in detail, the early and mid-term response of ventricular function to AVR procedures (surgical and TAVI) as well as post operative patients’ exercise capacity. Methods：We studied LV and RV function by Doppler echocardiography and speckle tracking echocardiography (STE) in the following 4 groups; (1) 30 severe AS patients (age 62±11 years, 19 male) with normal LV ejection fraction (EF) who underwent AVR, (2) 20 severe AS patients (age 79±6 years, 14 male) who underwent TAVI, (3) 30 healthy controls (age 63±11 years, 16 male), (4) 21 healthy controls (age 57±9 years, 14 male) who underwent exercise echocardiography. Results: After one week of TAVI, the septal radial motion and RV tricuspid annulus peak systolic excursion (TAPSE) were not different from before, while surgical AVR had significantly reversed septal radial motion and TAPSE dropped by 70% compared to before. The extent of the reversed septal motion correlated with that of TAPSE (r=0.78, p<0.001) in the patients as a whole after AVR and TAVI (Study I). Compared with controls, the LV twist function was increased in AS patients before and normalized after 6 months of surgical AVR. In controls, the LV twist correlated with LV fractional shortening (r=0.81, p<0.001), a relationship which became weak in patients before (r=0.52, p<0.01) and after AVR (r=0.34, p=ns) (Study II). After 6 months of surgical AVR, the reversed septal radial motion was still significantly lower than before. The septal peak displacement also decreased and its time became prolonged. In contrast, the LV lateral wall peak displacement increased and the time to peak displacement was early. The accentuated lateral wall peak displacement correlated with the septal peak displacement time delay (r=0.60, p<0.001) and septal-lateral time delay (r=0.64, p<0.001) (Study III). In 21 surgical AVR patients who performed exercise echocardiography, the LV function was normal at rest but different from controls with exercise. At peak exercise, oxygen consumption (pVO2) was lower in patients than controls. Although patients could achieve cardiac output (CO) and heart rate (HR) similar to controls at peak exercise, the LV systolic and early diastolic myocardial velocities and strain rate as well as their delta changes were significantly lower than controls. pVO2 correlated with peak exercise LV myocardial function in the patients group only, and the systolic global longitudinal strain rate (GLSRs) at peak exercise was the only independent predictor of pVO2 in multivariate regression analysis (p=0.03) (Study IV). Conclusion: Surgical AVR is an effective treatment for AS patients, but results in reversed septal radial motion and reduced TAPSE. The newly developed TAVI procedure maintains RV function which results in preservation of septal radial motion. In AS, the LV twist function is exaggerated, normalizes after AVR but loses its relationship with basal LV function. While the reversed septal motion results in decreased and delayed septal longitudinal displacement which is compensated for by the accentuated lateral wall displacement and the time early. These patients remain suffering from limited exercise capacity years after AVR.

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22

CLERICI, ALBERTO. "Development of a novel technology platform for thoracoscopic aortic valve replacement." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2745352.

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23

Dellgren, Göran. "Aortic valve replacement with stentless bioprostheses : prospective long-term studies of the Biocor and the Toronto SPV /." Stockholm : Karolinska institutet, 2002. http://diss.kib.ki.se/2002/91-7349-152-7.

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24

Kanamori, Norio. "Prognostic Impact of Aortic Valve Area in Conservatively Managed Patients With Asymptomatic Severe Aortic Stenosis With Preserved Ejection Fraction." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263349.

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25

Barbosa, Ribeiro Henrique. "Incidence, predictors and outcomes of myocardial injury following transcatheter aortic valve replacement." Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26635.

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Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2015-2016 L’implantation de valve aortique par cathéter (TAVI) a été développée comme une alternative thérapeutique pour les patients avec une sténose aortique sévère et ayant un risque opératoire élevé ou extrême en cas de chirurgie de remplacement valvulaire standard. Par rapport à la chirurgie à cœur ouvert classique, les procédures de TAVI sont moins invasives, parce qu'elles ne sont pas associées au clampage aortique et à la cardioplégie. Toutefois, la procédure implique un certain degré de dommage myocardique dû à la compression du tissu par le ballonnet et la prothèse transcathéter, ainsi que plusieurs courts épisodes d'hypotension extrême et d’ischémie myocardique globale, au cours de la stimulation ventriculaire rapide et du déploiement de la prothèse. De plus, l'approche transapicale, qui est réalisée lorsque l'approche transfémorale n’est pas possible, comprend la ponction de l'apex du ventricule gauche et l'introduction de larges cathéters ce qui augmente vraisemblablement encore les dommages myocardiques. En conséquence, presque tous les patients subissant un TAVI présentent un certain degré de dommage myocardique, défini par une augmentation des enzymes cardiaques, telles que la créatine kinase-MB (CK-MB), la troponine ou le peptide natriurétique de type B (BNP). Néanmoins, les données sur l'incidence exacte des dommages myocardiques, leur étendue, leurs prédicteurs, ainsi que les résultats échocardiographiques et cliniques associés, en fonction des différentes approches et prothèses sont limitées. Les objectifs généraux de mon projet de doctorat sont d'évaluer l'incidence, les facteurs prédictifs et les résultats des dommages myocardiques après TAVI pour le traitement des patients symptomatiques avec sténose aortique sévère ou bioprothèse dysfonctionnelle et à haut risque chirurgical. Transcatheter aortic valve replacement (TAVR) has emerged as a less invasive therapeutic alternative to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis at very high-risk or prohibitive perioperative risk. Compared to conventional open-heart surgery, TAVR procedures are less invasive, because they are not associated with aortic cross-clamping and cardioplegia. Even so, the procedure involves some degree of myocardial injury due to tissue compression, caused by the balloon and valve prosthesis, as well as several short episodes of extreme hypotension and global ischemia, during rapid ventricular pacing and valve deployment. Also, the transapical approach, which is an alternative to the transfemoral approach, involves the puncture of the ventricular apex and the introduction of large catheters through it. Accordingly, nearly all patients undergoing TAVR present some degree of myocardial injury, as defined by any increase in cardiac biomarkers, including creatine kinase-MB (CK-MB), troponin or B-type natriuretic peptides (BNP). Nonetheless, data on the exact incidence of myocardial injury, extent, predictors, as well as the associated echocardiographic and clinical outcomes, according to the different type of TAVR procedures and transcatheter valves, have been limited. The general objectives of my PhD project are to evaluate the incidence, predictors and outcomes of myocardial injury following TAVR for the treatment of high-risk patients with severe symptomatic AS or dysfunctional aortic bioprosthesis.

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KARAR, Mohamed Esmail Abdel Razek Hassan. "Development of a Surgical Assistance System for Guiding Transcatheter Aortic Valve Implantation." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-83426.

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Development of image-guided interventional systems is growing up rapidly in the recent years. These new systems become an essential part of the modern minimally invasive surgical procedures, especially for the cardiac surgery. Transcatheter aortic valve implantation (TAVI) is a recently developed surgical technique to treat severe aortic valve stenosis in elderly and high-risk patients. The placement of stented aortic valve prosthesis is crucial and typically performed under live 2D fluoroscopy guidance. To assist the placement of the prosthesis during the surgical procedure, a new fluoroscopy-based TAVI assistance system has been developed. The developed assistance system integrates a 3D geometrical aortic mesh model and anatomical valve landmarks with live 2D fluoroscopic images. The 3D aortic mesh model and landmarks are reconstructed from interventional angiographic and fluoroscopic C-arm CT system, and a target area of valve implantation is automatically estimated using these aortic mesh models. Based on template-based tracking approach, the overlay of visualized 3D aortic mesh model, landmarks and target area of implantation onto fluoroscopic images is updated by approximating the aortic root motion from a pigtail catheter motion without contrast agent. A rigid intensity-based registration method is also used to track continuously the aortic root motion in the presence of contrast agent. Moreover, the aortic valve prosthesis is tracked in fluoroscopic images to guide the surgeon to perform the appropriate placement of prosthesis into the estimated target area of implantation. An interactive graphical user interface for the surgeon is developed to initialize the system algorithms, control the visualization view of the guidance results, and correct manually overlay errors if needed. Retrospective experiments were carried out on several patient datasets from the clinical routine of the TAVI in a hybrid operating room. The maximum displacement errors were small for both the dynamic overlay of aortic mesh models and tracking the prosthesis, and within the clinically accepted ranges. High success rates of the developed assistance system were obtained for all tested patient datasets. The results show that the developed surgical assistance system provides a helpful tool for the surgeon by automatically defining the desired placement position of the prosthesis during the surgical procedure of the TAVI Die Entwicklung bildgeführter interventioneller Systeme wächst rasant in den letzten Jahren. Diese neuen Systeme werden zunehmend ein wesentlicher Bestandteil der technischen Ausstattung bei modernen minimal-invasiven chirurgischen Eingriffen. Diese Entwicklung gilt besonders für die Herzchirurgie. Transkatheter Aortenklappen-Implantation (TAKI) ist eine neue entwickelte Operationstechnik zur Behandlung der schweren Aortenklappen-Stenose bei alten und Hochrisiko-Patienten. Die Platzierung der Aortenklappenprothese ist entscheidend und wird in der Regel unter live-2D-fluoroskopischen Bildgebung durchgeführt. Zur Unterstützung der Platzierung der Prothese während des chirurgischen Eingriffs wurde in dieser Arbeit ein neues Fluoroskopie-basiertes TAKI Assistenzsystem entwickelt. Das entwickelte Assistenzsystem überlagert eine 3D-Geometrie des Aorten-Netzmodells und anatomischen Landmarken auf live-2D-fluoroskopische Bilder. Das 3D-Aorten-Netzmodell und die Landmarken werden auf Basis der interventionellen Angiographie und Fluoroskopie mittels eines C-Arm-CT-Systems rekonstruiert. Unter Verwendung dieser Aorten-Netzmodelle wird das Zielgebiet der Klappen-Implantation automatisch geschätzt. Mit Hilfe eines auf Template Matching basierenden Tracking-Ansatzes wird die Überlagerung des visualisierten 3D-Aorten-Netzmodells, der berechneten Landmarken und der Zielbereich der Implantation auf fluoroskopischen Bildern korrekt überlagert. Eine kompensation der Aortenwurzelbewegung erfolgt durch Bewegungsverfolgung eines Pigtail-Katheters in Bildsequenzen ohne Kontrastmittel. Eine starrere Intensitätsbasierte Registrierungsmethode wurde verwendet, um kontinuierlich die Aortenwurzelbewegung in Bildsequenzen mit Kontrastmittelgabe zu detektieren. Die Aortenklappenprothese wird in die fluoroskopischen Bilder eingeblendet und dient dem Chirurg als Leitfaden für die richtige Platzierung der realen Prothese. Eine interaktive Benutzerschnittstelle für den Chirurg wurde zur Initialisierung der Systemsalgorithmen, zur Steuerung der Visualisierung und für manuelle Korrektur eventueller Überlagerungsfehler entwickelt. Retrospektive Experimente wurden an mehreren Patienten-Datensätze aus der klinischen Routine der TAKI in einem Hybrid-OP durchgeführt. Hohe Erfolgsraten des entwickelten Assistenzsystems wurden für alle getesteten Patienten-Datensätze erzielt. Die Ergebnisse zeigen, dass das entwickelte chirurgische Assistenzsystem ein hilfreiches Werkzeug für den Chirurg bei der Platzierung Position der Prothese während des chirurgischen Eingriffs der TAKI bietet

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27

Abessi, Ovais. "Leaflet Material Selection for Aortic Valve Repair." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30191.

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Leaflet replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. Hemodynamic performance and mechanical stress levels were investigated after porcine AVr with 5 types of clinically relevant replacement materials to ascertain which material(s) would be best suited for repair. Porcine aortic roots with intact aortic valves were placed in a left-heart simulator mounted with a high-speed camera for baseline valve assessment. Then, the non-coronary leaflet was excised and replaced with autologous porcine pericardium (APP), glutaraldehyde-fixed bovine pericardial patch (BPP; Synovis™), extracellular matrix scaffold (CorMatrix™), or collagen-impregnated Dacron (HEMASHIELD™). Hemodynamic parameters were measured over a range of cardiac outputs (2.5–6.5L/min) post-repair. Material properties of the above materials along with St. Jude Medical™ Pericardial Patch with EnCapTM Technology (SJM) were determined using pressurization experiments. Finite element models of the aortic valve and root complex were then constructed to verify the hemodynamic characteristics and determine leaflet stress levels. This study demonstrates that APP and SJM have the closest profiles to normal aortic valves; therefore, use of either replacement material may be best suited. Increased stresses found in BPP, HEMASHIELD™, and CorMatrix™ groups may be associated with late repair failure.

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Nakatsu, Taro. "Intermediate-term outcomes of aortic valve replacement with bioprosthetic or mechanical valves in patients on hemodialysis." Kyoto University, 2020. http://hdl.handle.net/2433/252979.

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DELLA, ROSA FRANCESCO. "Impact of asymptomatic carotid stenosis on mid term outcome of transcatheter aortic valve replacement." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/105574.

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Introduction Stroke is a potential major complication of aortic valve replacement (AVR), transcatheter aortic valve implantation (TAVI), and balloon aortic valvuloplasty (BAV). Although its occurrence is rare, stroke significantly affects survival and quality of life. Peripheral vascular disease and carotid artery disease are independent risk factors that have been identified as predictors of operative death according to surgical risk scores. The presence of a significant carotid stenosis may increase the surgical risk leading to the choice of a percutaneous transaortic valve implantation rather than a surgical AVR. At present there is no evidence that describes the impact of asymptomatic significant carotid stenosis detected accidentally during preoperative evaluation on the onset of cerebrovascular periprocedural events after TAVI. Population In this first analysis we considered 521 patients with severe aortic stenosis (AS) and cardiac symptoms (New York Heart Association [NYHA] class II function or worse). A score of at least 20 % on the EuroSCORE (European System for Cardiac Operative Risk Evaluation) and 10% on the risk model developed by the Society for Thoracic Surgeons (STS)., Follow-up All patients underwent clinical surveillance, bio-chemical tests, electrocardiogram and echocardiogram before hospital discharge. The follow-up assessment included medical examination, electrocardiogram and echocardiogram to perform valve imaging and hemodynamic evaluation. It was performed at our Center or at the treating cardiologist ambulatory 30 days and one year after the procedure. The events considered were mortality (by all-cause and cardiovascular death), myocardial infarction, stroke and transient ischemic attack (TIA), bleeding (minor and life-threatening bleeding), acute renal failure, vascular complications, disturb of conduction and arrhythmias and the combined criteria of safety, according to VARC and VARC 2 definitions. Procedure The coexistence of carotid and peripheral artery diseases not only further increases risk and long-term mortality but influences also technical approaches since all centers adopt a policy of using the transfemoral approach first, with criteria for the use of non-transfemoral approaches that are based on the size and degree of tortuosity, calcifications, and atheroma of the aorto-iliofemoral arterial tree, as assessed by the multidisciplinary team. In our Center, preventive measures have been taken to limit the risk associated to the procedure in our patients presenting carotid artery stenosis. Results The main findings of the current study are the following: (a) no correlation has been observed about the presence of an asymptomatic carotid artery stenosis discovered before the TAVI procedure and mortality, rate of cerebrovascular events (stroke or TIA) and myocardial infarction during the first postoperative month; (b) no differences concerning all-causes and cardiovascular mortality and onset of cerebrovascular events (stroke/TIA) at long-term have been shown between patients with and without CAS. Conclusion The presence of asymptomatic carotid stenosis is not a risk factor for cerebrovascular events after percutaneous aortic valve implantation at 30 days and one-year follow-up. Cerebrovascular events after TAVI occur in a vulnerability period extending to 1 month post-procedure. No difference exists in the CVE rate with regard to the type of valve or the access route. Coronary, carotid, aortic, iliac and femoral artery disease are often found in elderly patients presenting with severe symptomatic AS undergoing TAVI. These patients are also affected by several clinical factors and frailty that correlate with the presence and severity of arterial pathologies and can impact on incidence of CVEs and longterm survival

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Besada, Joona. "A Virtual Heart Valve Implant System : Navigating the idea space and developing a proof of concept for virtual transcatheter aortic valve replacement." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168740.

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Aortic stenosis is a disease that causes a narrowing of the aortic valve opening. It is a disease that can be found in more than 2% of the elderly population. In the past, the only effective treatment has been open heart valve replacement, but in the last decade it has become possible to also treat aortic stenosis through a percutaneous procedure known as transcatheter aortic valve replacement. An implant-carrying catheter is led up to the patient’s heart where the implant is deployed. Sizing, positioning, and orientation of the implant are important considerations in transcatheter aortic valve replacement. Purpose: The purpose was to investigate the feasibility and potential features of a virtual heart valve implant system and how the available assets at the Medical Devices Center and its collaborators could create a useful tool for virtual transcatheter aortic valve implant selection, sizing, positioning, and orientation. Implementation: Challenges with transcatheter aortic valve replacement among clinicians and engineers were identified. A virtual heart valve implant system was proposed as a solution. The idea space for a virtual heart valve implant system was explored and structured systematically with a new approach called the idea connection tree method. A proof of concept prototype with a 3D model of an aorta and an implant in three different sizes was created as a way to gauge if there is user value in a virtual heart valve implant system. Result & Conclusion: For the proposed solution of a virtual heart valve implant system, 43 unique ideas were generated. Three main branches of ideas were identified: Design, simulation, and a database branch. It was estimated that the simulation branch would provide the most user value for comparatively low work effort. The proof of concept prototype showed that it was possible to visually evaluate the interference produced by different sized implants inside a 3D model of an aorta on a virtual reality system. Aortastenos är en sjukdom som orsakar förträngning av aortaklafföppningen. Det är en sjukdom som återfinns hos mer än 2% av den äldre befolkningen. Tidigare har den enda effektiva behandlingen inneburit hjärtklaffersättning med öppen hjärtkirurgi, men under det senaste decenniet har det blivit möjligt att också behandla aortastenos med en perkutär procedur i form av kateterburen implantation av aortaklaff. En kateter som bär på en aortaklaffprotes förs fram till patientens hjärta där protesen sedan utplaceras. Dimensionering, positionering och orientering av protesen är viktiga överväganden i kateterburen implantation av aortaklaff. Syfte: Syftet är att undersöka genomförbarheten och potentiella funktioner hos ett virtuellt implanteringssystem för hjärtklaffproteser och hur tillgångarna hos Medical Devices Center och deras samarbetspartners kan skapa ett användbart verktyg för virtuell dimensionering, positionering samt orientering av kateterburna hjärtklaffproteser. Implementering: Utmaningar med kateterburen hjärtklaffimplantering bland kliniker och ingenjörer identifierades. Ett virtuellt implanteringssystem för hjärtklaffproteser föreslogs som en lösning. Idérymden utforskades och strukturerades systematiskt med en ny metod kallad för idésambandsträd-metoden. En konceptprototyp med 3D modeller på en aorta och en protes i tre olika storlekar skapades för att uppskatta om det finns användarvärde i ett virtuellt implanteringssystem för hjärtklaffproteser. Resultat & Slutsats: För den föreslagna lösningen av ett virtuellt implanteringssystem för hjärtklaffproteser genererades 43 unika idéer. Tre huvudsakliga grenar av idéer identifierades: Konstruering, simulering och en databasgren. Det uppskattades att simuleringsgrenen skulle kunna förse den största mängden användarvärde för en förhållandevis låg arbetsinsats. Konceptprototypen visade att det var möjligt att visuellt utvärdera interferensen av olika protesstorlekar inuti en 3D model av en aorta med hjälp av ett virtual reality system.

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Zappe, Ann-Katrin Reglinde [Verfasser]. "Follow-Up bei Patienten nach perkutaner Valve-in-Valve Aortenklappenimplantation : Patients with transcatheter valve-in-valve implantation for failed surgical aortic valves / Ann-Katrin Reglinde Zappe." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/1223928322/34.

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Zahaf, Marwah. "Effect of Transcatheter Aortic Valve Replacement on Right Ventricular Function| Meta analyses and Systematic Review." Thesis, Rush University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=1581898.

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Objectives: We ought to compare the effect of transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) on right ventricular systolic function (RVSF) in high risk patients with severe aortic stenosis (AS). Methodology: Data Source. PubMed, EMBASE, Cochrane library, and references of selected articles. Study Endpoints. Transthoracic echocardiography was utilized to assess the change in RVSF post TAVR versus SAVR using tricuspid annular plane systolic excursion (TAPSE), and Fractional area change (RVFAC). Statistical analyses. Random effect model on standardized mean difference (Hedges; g) were used together with heterogeneity assessment. Result: We included 485 patients from five single-center observational studies. Comparing TAVR with SAVR, TAVR resulted in better improvement in RVSF [TAPSE (g=2.88, SE=0.63, P<0.001, Q=73.18, /2=94.53, r=0.65), and RVFAC (g=0.91, SE=0.16, P<0.001, Q=2.39, /2=16.61), r=0.65]. Conclusion: Compared with SAVR, TAVR is preferred aortic intervention in patients with severe symptomatic AS and RV systolic dysfunction.

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Semelhago, Lloyd C. "Evaluating bioprosthetic devices in aortic valve surgery: Systematic assessment and design of cardiac surgical trials." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/27034.

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Producing quality randomized controlled trials in the field of surgery and, in particular, cardiac surgery can be a formidable task. Surgeons face difficulties not frequently encountered in non-surgical studies. Addressing the difficulties peculiar to this medical specialty may improve the quality of future surgical trials. Issues such as blinding, sample size, control groups and bias are but a few of the dilemmas that must be attended to in order to design a good quality surgical study. This thesis evaluates the quality of surgical studies available in the cardiac surgical literature, identifies obstacles encountered, and seeks to develop guidelines for future cardiac surgical protocols. Studies using aortic valve replacement procedures are the focus of the thesis. An extensive literature search on aortic valve replacement encompassing publications from 1986-2004 was used to evaluate the quality of surgical studies. A pool of 646 studies was narrowed down to 23 papers which were selected for detailed analysis. In the second part of the thesis, a list of obstacles to conducting surgical trials was constructed from the literature and the author's experience. A revised list of obstacles based on the experience from the systematic review was developed. This list was then applied to a year of publications of the Journal of Thoracic and Cardiovascular Surgery and the Annals of Thoracic Surgery . A final list was then developed consisting of obstacles encountered in conducting clinical trials in surgery. Finally, the U.K. Medical Research Council guidelines as adapted by the Canadian Institutes of Health Research were used in conjunction with the information procured in this study to generate guidelines for conducting surgical trials and applied in developing a specific protocol for comparing two bioprosthetic heart valves.

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Hagen-Peter, Gayle Ann. "Living with Aortic Stenosis: A Phenomenological Study of Patients' Experiences and Subsequent Health Choices." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/516.

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Symptomatic aortic stenosis (AS) is an increasing phenomenon as more adults live longer. The gold standard for treating AS is surgical aortic valve replacement (SAVR). Frequently, as older individuals with AS often have multiple comorbidities, a SAVR is determined to be too high risk. Therefore, a less invasive treatment option is available, namely a transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR). Such biomedical procedures have encouraged life extension and the decision to intervene commonplace with the aging population. Without an intervention, significant debilitating symptoms affect a person's quality of life (QoL). Multiple quantitative studies evaluating QoL before and after a TAVI have been performed. However QoL has multiple attributes and is not a single construct. By limiting practice to these defined QoL measures, we exclude the human experience and what values individuals describe as important to them. The dilemma in the present medical model is influenced by two paradigms, evidence based medicine and patient centered medicine. Some people opt not to have a TAVI. This study aims to understand what it is like living with aortic stenosis as perceived by the participant and to gain a more meaningful understanding of why some individuals with AS choose not to have this procedure performed. Using a convenience sample of patients who declined a TAVI, a telephone interview with the person focused on their perceived QoL and the implications determining not to pursue a TAVI. In this qualitative phenomenological design, open-ended questions included: 1) What is it like to live with Aortic Stenosis. 2) Why did you choose not to have the TAVI? Interviews will explore emerging themes. Advanced practice nurses are in ideal positions for performing research to gain greater insight on the complexity of people's health choices. As the incidence of AS occurs more frequently in the increasing aged population, TAVI offers a treatment option for those patients who are symptomatic with AS and are not surgical candidates. However, health care providers should focus on the illness, not the disease, and explore the patients' biopsychosocial values with their medical needs. The information gathered in this study will help guide heath care providers with offering holistic health care incorporating both paradigms of evidence based practice and patient centered medicine options on treatment for people with symptomatic AS.

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Alkhalil, Ahmad. "Outcomes Of Early Versus Late Discharge In Transfemoral Transcatheter Aortic Valve Replacement Via Minimally Invasive Strategy: A Propensity-Matched Analysis." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1465592493.

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Miyake, Makoto. "Early Surgery vs. Surgery After Watchful Waiting for Asymptomatic Severe Aortic Stenosis." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/264637.

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Muta, Eri. "Impact of the left ventricular mass index on the outcomes of severe aortic stenosis." Kyoto University, 2019. http://hdl.handle.net/2433/242385.

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Kumar, Anirudh. "SAFETY AND EFFICACY OF BALLOON AORTIC VALVULOPLASTY STRATIFIED BY ACUITY OF PATIENT ILLNESS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1623349720127583.

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Straiton, Nicola. "The acceptability of heart valve replacement procedures, and patient-reported outcomes in adults with aortic stenosis." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29843.

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The incidence of aortic stenosis (AS) is high and increasing alongside the aging of populations in developed countries. Yet the impact of severe AS and associated treatments on the lives of people and their carers who provide support, is poorly understood. This thesis aims to investigate patient-reported outcomes of severe AS and valve replacement for adults living with AS and the acceptability of these replacement procedures for individuals and their carers. A multi-method study was conducted, consisting of two systematic reviews one of which synthesised the evidence for functional capacity and health-related quality of life (HRQoL) outcomes after transcatheter aortic valve replacement (TAVR), and another determining the validity and reliability of consumer-grade wearables to monitor physical activity in older, community-dwelling adults. Additionally, a study (n=32) measuring AS patients' functional capacity, physical activity and HRQoL before and after AVR and a descriptive, qualitative study exploring the acceptability of TAVR to patients (n=18) and their carers (n=8) were conducted. Before valve replacement severe AS patients had poor functional capacity, physical activity and HRQoL. Evidence from the reviews and the study demonstrated that for most people with severe AS, AVR by any mode improves functional capacity and overall HRQoL and that wearable activity trackers can accurately measure physical activity amongst older adults. AS patients and their carers found TAVR to be an acceptable intervention to treat the condition, addressing pre-operative symptom-driven emotions of struggling and fear, and fostering post-operative feelings of confidence and an ability to get back to a sense of normal. Furthermore, TAVR aligned with participants’ values, preferences and needs. Understanding the impact of severe AS on the lives of patients and their carers will enable clinicians to tailor clinical support before and after treatment.

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De, Rui Marina. "Aortic valve replacement in elderly subjects: effects on physical performance, cognitive function and quality of life." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425391.

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Background: aortic valve stenosis (AVS) is becoming more and more common in the elderly population, involving around 13.2% of subjects older than 75 years. In addition to worsening quality of life, untreated severe AVS has been associated with high short term mortality rate. However, these adverse outcomes could be modified by aortic valve replacement (AVR). In recent years, in particular, newer surgery procedures and anesthesiological techniques have allowed also older and frailer patients access to AVR procedures. Previous studies have evaluated the effectiveness of AVR in older subjects in terms of peri- and post-operative mortality, but its impact on frail patients’ global health has been scarcely investigated. Aim of the study: the aim of our study was to evaluate the impact of AVR procedure on older patients’ physical performance, cognitive status and quality of life at 45 days, three and six months after surgery. Subjects and methods: this prospective study included 46 patients over 70 years, enrolled in collaboration with the Department of Cardiac Surgery of the University of Padova. All subjects were affected by AVS, and were recommended to undergo AVR. Study participants were evaluated with a multidimensional geriatric assessment before AVR (T0) and 45 days (T1), three (T2) and six months (T3) after surgery. In particular, for each participant we collected data on clinical examination, self-sufficiency (using the Activites of Daily Living and Instrumental Activites of Daily Living scales), cognitive status (using the Mini Mental State Examination and the Montreal Cognitive Assessment), presence of depressive symptom (through the Geriatric Depression Scale), quality of life (using the Short-Form 36 items Health Survey) and physical performance (through the Short Physical Performance Battery, gait speed, 6-minute walking test, and measurements of upper and lower limbs strength). Results: of the initial sample of 46 patients, 22 reached the 6-month follow-up and were included in the study. Compared with the pre-operative evaluation, at T1 we observed a significant decline in nutritional status (BMI, arm circumference, MNA score) and in physical performance (SPPB, handgrip strength, lower limb flexion-extension and isometric strength). At T3, MMSE, MoCA, MNA and SPPB scores improved significantly from baseline. Upper and lower limbs strength at 6-month follow up was not significantly different from baseline. Quality of life remained nearly stable at T1, but improved significantly at T2 and T3. Considering the variation in gait speed from baseline to 6-month follow up, subjects that showed an improvement in this item compared to worsening subjects, at baseline had lower values of handgrip and limbs strength, gait speed and 6-MWT distance. Conclusions: our results show that in older AVS patients, AVR have a positive impact on nutrition, physical performance, cognitive functioning, mood and quality of life, whereas it does not have any significant impact on limbs muscle strength. Premessa: la stenosi valvolare aortica (AVS) sta diventando sempre più frequente nella popolazione anziana, coinvolgendo circa il 13.2% dei soggetti sopra i 75 anni. Oltre a compromettere la qualità della vita, la AVS di grado severo non trattata porta alla morte in un tempo relativamente breve. La storia naturale della AVS può essere modificata dalla sostituzione della valvola aortica (AVR). I progressi nelle tecniche operatorie e anestesiologiche hanno ampliato negli ultimi anni l’accesso all’intervento chirurgico a pazienti sempre più anziani e sempre più fragili. In letteratura gli studi hanno finora valutato l’efficacia della AVR nel paziente anziano in termini di mortalità peri- e post-operatoria, mentre mancano dati circa l’esito dell’intervento sulla salute globale del paziente fragile a medio termine. Scopo dello studio: lo scopo del nostro studio era valutare nel soggetto anziano l’impatto dell’intervento di AVR sulla performance fisica, sullo stato cognitivo e sulla qualità di vita a distanza di 45 giorni, tre e sei mesi dall’intervento chirurgico. Soggetti e metodi: in collaborazione con l’U.O. Cardiochirurgia, secondo un disegno osservazionale longitudinale sono stati studiati 46 pazienti di età > 70 anni affetti da AVS per i quali era stata posta indicazione all’AVR. I soggetti sono stati valutati prima dell’intervento chirurgico (T0) e dopo l’intervento chirurgico a 45 giorni (T1), a tre mesi (T2) e a 6 mesi (T3). In tutte le visite i soggetti sono stati sottoposti a una valutazione geriatrica multidimensionale, comprensiva di esame clinico, valutazione dell’autonomia funzionale (Activites of Daily Living e Instrumental Activites of Daily Living Scales), dello stato cognitivo (Mini Mental State Examination, Montreal Cognitive Assessment), del tono dell’umore (Geriatric Depression Scale), della qualità di vita (Short-Form 36 items Health Survey, SF-36) e della performance fisica (Short Physical Performance Battery, Gait Speed, Six minute Walking Test, misurazione della forza massimale degli arti superiori e inferiori). Risultati: dei 46 pazienti inclusi nello studio in questo lavoro sono stati considerati solo i 22 soggetti che hanno completato il follow-up a 6 mesi. Rispetto alla valutazione preoperatoria, al follow-up dei 45 giorni era evidente un significativo peggioramento nei parametri nutrizionali (BMI,circonferenza del braccio, punteggio MNA) e dei test di performance fisica (forza massimale di prensione della mano, forza di flesso-estensione degli arti inferiori e test isometrico della forza degli arti inferiori). Al follow-up dei 6 mesi MNA, MMSE, MoCA, SPPB miglioravano significativamente, raggiungendo valori superiori a quelli basali. La forza degli arti superiori e inferiori non si modificava significativamente 6 mesi dopo l’intervento rispetto al basale. Per ciò che concerne la qualità di vita, i punteggi all’SF-36 rimanevano pressoché stabili a 45 giorni mentre miglioravano significativamente al controllo a 3 e a 6 mesi. Considerando la variazione della velocità del passo tra la valutazione basale e quella a 6 mesi, i soggetti che presentavano un miglioramento nel follow up, rispetto agli altri soggetti al basale presentavano valori più bassi di forza degli arti superiori e inferiori, di velocità del passo e percorrevano una distanza significativamente inferiore al 6-MWT. Conclusioni: i dati di questo studio evidenziano che nei pazienti anziani affetti da AVS, la sostituzione valvolare aortica migliora lo stato nutrizionale, le facoltà cognitive, il tono dell’umore, la performance fisica e la qualità di vita. La forza degli arti inferiori e superiori invece mantiene a 6 mesi valori non diversi da quelli pre-operatori. I soggetti che sembrano beneficiare maggiormente dal punto di vista funzionale della AVR sono quelli più compromessi a basale dal punto di vista della performance fisica.

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BERTOLDO, FABIO. "La protesi Valsalva nella chirurgia sostitutiva della radice aortica con conservazione della valvola nativa: follow-up a lungo termine." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/208570.

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Introduzione: La tecnica di sostituzione della radice aortica con conservazione della valvola nativa è sicura e caratterizzata da buoni risultati sia immediati che a distanza. Per migliorare ulteriormente i risultati a lungo temine, sono state ideate varie modifiche con l’intento di ricostruire la complessa struttura anatomo-funzionale della radice aortica. La protesi Valsalva sembrerebbe utile per ricreare più fedelmente tale struttura e consentirebbe anche una maggiore riproducibilità e standardizzazione di questa tecnica. Abbiamo analizzato retrospettivamente i nostri dati relativi all’intervento chirurgico ed al periodo immediatamente postoperatorio ed i dati ottenuti durante il follow-up.Pazienti e metodi: Da maggio 2000 ad ottobre 2009, 42 pazienti (36 di sesso maschile, età media di 53 ± 10 anni) venivano sottoposti ad intervento chirurgico di sostituzione della radice aortica con reimpianto della valvola nativa, utilizzando la protesi Valsalva. Sedici pazienti (38,1%) erano affetti da sindrome di Marfan e 2 (4,8%) presentavano valvola aortica bicuspide. Quindici pazienti (35,7%) venivano sottoposti ad altre procedure concomitanti. Risultati: La mortalità ospedaliera è risultata del 2,4%. Il follow-up, completo al 100%, presenta una durata media di 80 ± 36 mesi (mediana 94 mesi e range da 0 a 120 mesi). Si verificavano 4 decessi durante il periodo di osservazione, per cui la probabilità di sopravvivenza cumulativa a 10 anni è risultata dell’88,1%. In 7 pazienti (16,4%) si osservavano risultati non soddisfacenti: la probabilità di libertà da recidiva di insufficienza valvolare aortica, ma senza necessità di re-intervento, a 10 anni è risultata del 95,2%, mentre la probabilità di libertà da re-intervento a 10 anni è risultata dell’88,1%. Background: The reimplantation valve-sparing aortic root replacement is safe and characterized by short and long-term good results. Several modifications have been proposed to rebuilt the complex anatomo-functional structure of the aortic root in the attempt to improve the long-term results. The Valsalva graft appears to be useful in order to recreate more closely such a structure also concurring to a greater reproducibility and standardization of this technique. We retrospectively analyzed our perioperative and long-term follow-up data. Methods: From May 2000 to October 2009, 42 patients (36 males, mean age of 53±10 years) underwent reimplantation valve-sparing aortic root replacement using the Valsalva graft. Sixteen patients (38.1%) had Marfan syndrome and 2 (4.8%) had bicuspid aortic valve. Fifteen (35.7%) underwent concomitant cardiac procedures. Results: The in-hospital mortality was 2.4%. There were no dropouts at the follow-up, which lasted 80 ± 36 months (median 94 months and range from 0 to 120 months). There were 4 late deaths during the period of observation, and so the 10-years cumulative actuarial survival was 88.1%. In 7 patients (16.4%) did not show satisfactory results: the 10-years freedom from recurrence of aortic insufficiency not needing reoperation was 95.2%, while the 10-years freedom from aortic valve reoperation was 88.1%. Conclusions: The reimplantation valve-sparing aortic root replacement using the Valsalva graft is safe and characterized by a low in-hospital mortality. The peculiar reconstruction of the aortic root, guaranteed by this conduit, positively influences the long-term results. Moreover, the Valsalva graft appears to favour a good reproducibility and a good standardization of this procedure.

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Kidher, Emaddin. "The relationship between aortic stiffness, health related quality of life and post-operative organs recovery (cardiac, renal and cognitive) following aortic valve replacement." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/33126.

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Background: Aortic stiffness as measured by pulse wave velocity (PWV) is a predictor of cardiovascular disease and other outcomes in different diseased and healthy populations, independent of traditional risk factors. The relationships between PWV measurement, global functional outcome and injury to the brain, kidney, and heart have never been examined in cardiac surgery patients. Objective: The objective of this project was to assess the relationship between aortic stiffness and health related quality of life (QoL), cognitive function, acute kidney injury (AKI), and cardiac function in patients undergoing aortic valve replacement (AVR). Methods: Aortic PWV, QoL, cognitive function, left ventricular (LV) function and NYHA class were assessed pre- and post-operatively (409 ± 159 days). The brain injury biomarker, N-methyl-D-aspartate receptor antibody (NR2Ab), was measured pre-operatively only. The biomarker of myocardial strain, B-type natriuretic peptide (BNP), and the novel AKI biomarker, neutrophil gelatinase-associated lipocalin (NGAL), were measured pre-operatively, and at 3 h and 18-24 h post-CPB. Results: Fifty-six patients (16 females; mean age, 71 ± 8.4 years) were included in this study, of which 50 (89%) patients attended the follow-up visit. No relationship was found between the degree of aortic stenosis (AS) and PWV, and AVR had no effect on aortic stiffness post-operatively. QoL and NYHA class significantly improved, while cognitive function did not deteriorate after AVR. High PWV is independently related to poorer QoL, cognitive function levels and NYHA class both pre- and post-operatively. PWV was not related to LV function, BNP or NGAL levels, but it was independently related to the level of NR2Ab. PWV did not correlate with AKI which was developed in 30% of the cases. Early post-operative plasma level of NGAL is the earliest predictive marker of post-operative AKI and the need for early medical renal intervention. Pre-operative BNP level was significantly and negatively correlated with pre-operative LV function, AS (valve area), and NYHA class in the post-operative follow-up period. Conclusion: In AVR patients, PWV is independently related to global functional status, cognitive function and brain injury biomarkers, but is not related to AKI or myocardial strain.

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Parche, Julius [Verfasser]. "Femoral access-site complications in patients undergoing transcatheter aortic valve replacement with new generation devices / Julius Parche." Ulm : Universität Ulm, 2020. http://d-nb.info/1219146218/34.

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Bissessor, Naylin. "Complex Heart Valve Disease: Functional Capacity and Natriuretic Peptides Predict Outcomes in mixed and Multiple Heart Valve Disease." Thesis, Griffith University, 2013. http://hdl.handle.net/10072/367217.

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Chronic mixed and multiple heart valve disease constitutes a complex group of cardiac pathologies that are prevalent world wide causing significant mortality and morbidity. The American Heart Association and the European Society of Cardiology concede in their guidelines that little data exists in the international literature on this important subject. Patients tend to adopt a sedentary lifestyle in order to cope with this illness and avoid symptoms causing a steady decline in functional capacity. A physically active lifestyle is imperative for a good quality of life and cardiovascular wellness. Significant functional impairment through disease portends an adverse prognosis. Functional capacity impairment can be objectively measured through formal cardiopulmonary exercise testing through determining the peak oxygen consumption (peakVO2). Exercise intolerance may suggest significant underlying symptoms especially in asymptomatic or mildly symptomatic states with severe heart valve lesions. The onset of symptoms is central to the decision to operate and surgical valve replacement. The peakVO2 measurement is the international gold standard of functional aerobic capacity and is widely used in heart failure and cardiac transplant to predict prognosis and outcome. The role of peakVO2 has not been evaluated in complex heart valve disease. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) School of Medical Science Griffith Health Full Text

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Ogunrombi, Akinwumi Babatunde. "Sixteen year retrospective analysis of rheumatic and non-rheumatic heart disease patients undergoing valve procedures at Groote Schuur Hospital first incidence single aortic and mitral valve replacement." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/11525.

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Includes abstract. Includes bibliographical references. Rheumatic heart disease is still the most common cause of valvular heart lesions requiring replacement or repair procedures worldwide. In South Africa, where there is an interesting mix of first and third world dynamics, factors sustaining the epidemic of rheumatic disease are still commonplace. The choice of appropriate valve procedure and prosthesis in our setting will depend on an adequate knowledge of short and long term outcomes of valve replacement and repair. The aim of this thesis was to evaluate the demographics and presentation of our rheumatic and non-rheumatic patients and to determine if our current implantation choices could be validated.

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Almeida, Adriana Silveira de. "Comparação da sobrevida entre indivíduos submetidos à cirurgia para substituição valvar aórtica utilizando próteses mecânicas ou biológicas em uma coorte brasileira." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/28695.

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Este estudo avalia mortalidade, eventos hemorrágicos e reoperação em pacientes submetidos à cirurgia para troca valvar aórtica utilizando substituto biológico ou mecânico, com poder de relevância na seleção do tipo da prótese. Foram selecionados, randomicamente, 301 pacientes submetidos à cirurgia para troca valvar aórtica entre 1990 e 2005, com seguimento máximo de 20 anos. A sobrevivência em 5, 10 e 15 anos após cirurgia utilizando substituto mecânico foi de 83,9%, 75,4% e 60,2% e, para substituto biológico, foi de 89,3%, 70,4% e 58,4%, respectivamente (p=0,939). Os fatores associados com o óbito foram: idade, obesidade, doença pulmonar, arritmias, eventos hemorrágicos e insuficiência valvar aórtica. A probabilidade livre de reoperação desses pacientes em 5, 10 e 15 anos após cirurgia utilizando substituto mecânico foi de 97,9%, 95,8% e 95,8% e, para bioprótese, foi de 94,6%, 91,0% e 83,3%, respectivamente (p=0,057). Os fatores associados com reoperação foram: insuficiência renal, endocardite de prótese e idade. A probabilidade livre de eventos hemorrágicos em 5, 10 e 15 anos após cirurgia utilizando substituto mecânico foi de 94,5%, 91,7% e 91,7% e, para bioprótese, foi de 98,6%, 97,8% e 97,8%, respectivamente (p=0,047). Os fatores associados com eventos hemorrágicos foram: insuficiência renal e prótese mecânica. Os autores concluíram que: 1) a mortalidade foi estatisticamente semelhante entre os grupos; 2) as características basais dos pacientes foram os maiores determinantes de mortalidade tardia após a cirurgia; 3) houve uma tendência à reoperação para o grupo com bioprótese; 4) pacientes com prótese mecânica tiveram mais eventos hemorrágicos ao longo do tempo; 5) os dados encontrados no presente estudo são concordantes com a literatura atual. This paper evaluates mortality, bleeding events and reoperation in patients subjected to surgery for replacement of the aortic valve using a biological or a mechanical substitute, where selection of the type of prosthesis is relevant. Three hundred and one patients who had been subjected to aortic valve replacement surgery between 1990 and 2005, with a maximum follow-up period of 20 years, have been randomly selected. Survival at 5, 10 and 15 years after surgery using a mechanical substitute was 83.9%, 75.4% and 60.2% and, for a biological substitute, was 89.3%, 70.4% and 58.4%, respectively (p=0.939). Factors associated with death were: age, obesity, pulmonary disease, arrhythmia, bleeding and aortic valve failure. The probability free of reoperation for these patients at 5, 10 and 15 years after surgery using a mechanical substitute was 97.9%, 95.8% and 95.8% and, for those using bioprostheses, was 94.6%, 91.0% and 83.3%, respectively (p=0.057). Factors associated with reoperation were: renal failure, prosthesis endocarditis and age. The probability free of bleeding events at 5, 10 and 15 years after surgery using the mechanical substitute was 94.5%, 91.7% and 91.7% and, for bioprostheses, was 98.6%, 97.8% and 97.8%, respectively (p=0.047). Factors associated with bleeding events were: renal failure and mechanical prostheses. The authors have concluded that: 1) mortality was statistically similar in the groups; 2) patient characteristics at baseline were a major determinant of late mortality after surgery; 3) there was a tendency toward reoperation in the bioprostheses group; 4) patients using a mechanical prosthesis had more bleeding events as time passed; 5) the data presented in this paper is in accordance with current literature.

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Xu, Xiang [Verfasser]. "Investigation of circulating microRNAs in response to transcatheter aortic valve replacement and exploration of their cellular function in cardiovascular cells / Xiang Xu." Bonn : Universitäts- und Landesbibliothek Bonn, 2021. http://d-nb.info/1238687741/34.

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Boer, Berta Paula Napchan. "Comparação da função diastólica entre o pré e pós-operatório de pacientes portadores de estenose aórtica ou insuficiência aórtica, baseados em dados bioquímicos e ecocardiográficos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-30032010-181154/.

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INTRODUÇÃO: Avaliação da função diastólica de pacientes portadores de estenose ou insuficiência aórtica submetidos à troca valvar. OBJETIVOS: Avaliação da função diastólica através da análise do NTpró-BNP como método não invasivo para caracterização da insuficiência cardíaca diastólica, comparando com os dados ecocardiográficos através do Doppler Pulsado em Fluxo Mitral, Doppler Pulsado em Veias Pulmonares e Doppler Tecidual em portadores de IAO e EAO. MÉTODOS: Foram avaliados 63 pacientes, 32 pacientes com IAO (25 pacientes do sexo masculino e 7 do sexo feminino), 31 pacientes com EAO (11 pacientes do sexo masculino e 20 pacientes do sexo feminino). As variáveis foram comparadas na média entre os pacientes portador de IAO e EAO no pré e pós-operatório. RESULTADOS: A idade dos pacientes variou de 21 a 81 com média de 55 anos. Observa-se diferença quanto à média de idades entre as diferentes patologias (t-Student p< 0,0001). Os pacientes com IAO apresentam uma média de idade igual a 45,7±14,3 com variação entre 21 e 79 anos e os pacientes com EAO apresentam uma média de idade igual a 61,5±14,7 com variação entre 21 e 81 anos. Na IAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): TRIV (p=0,0011), diferença entre Tempo de onda A mitral e onda A pulmonar (p=0,0097), Vol. Sistólico de AE (p=0,0019), Vol Sistólico de AE Indexado (0,0011), Vol. Diastólico de AE (p=0,0110), DDVE (p<0,0001), DSVE (p<0,0001), VSF (p<0,0001), VDF (p<0,0001), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa do VE (p<0,0001). Na EAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): E/E (p=0,0379), TRIV (p=0,0072), diferença entre o tempo de onda A mitral e tempo de onda A pulmonar (p=0,0176), Vol sistólico de AE(p=0,0242), Vol. Sistólico de AE indexado (p=0,0237), FEdeAE (p=0,0339), DDVE (p=0,0002), DSVE (p=0,0085), VDF (p=0,0194), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa de VE(p<0,0001). O NTpró-BNP se correlacionou positivamente com os diversos graus de disfunção diastólica tanto no pré como pós-operatório CONCLUSÃO: Foram verificados no estudo da função diastólica variação com significância estatística tanto na IAO como na EAO na comparação do pré e o pós-operatório. Da mesma forma notamos variação do NT-proBNP com correlação com as variáveis ecocardiográficas que caracterizam a disfunção diastólica. INTRODUCTION: Assessment of diastolic function in patients with aortic stenosis or aortic regurgitation waiting for aortic valve replacement. OBJECTIVE: Assesment of diastolic function with Doppler methods:Doppler signals from transvalvar mitral inflow, tissue Doppler imaging (TDI) and Doppler in pulmonary veins(DPV) correlating with serum brain peptide natriuretic (NTproNP) before and 6 months after aortic valve replacement (AVR). METHODS: We have analyzed 63 patients, 32 with AR (25 males and 7 females), 31 AS (11 males and 20 females).The indices were compared with AS and AR before and after AVR. RESULTS: The ages of patients ranged from 21 to 81 mean age was 55 years old.We have seen difference between mean age of AS and AR (t-Student-p<0.0001). Patients with AR have had mean age 45.67 plus/minus 14.28, range 21 to 79 years old and patients with AS have had mean age 61.50 plus/minus 14.72, range 21 to 81 years old. The patients who had AR the indices showed differences: Isovolumetric Relaxation Time IRT(p=0.0011), Diference between the pulmonary A wave duration and mitral A duration (p=0.0097), Left Atrial Systolic Volume (p=0.0019), Left Atrial Systolic Volume Index(p=0.0011), Left Atrial Diastolic Volume (p=0.0110), Left Ventricular Diastolic Diameter (p<0.0001), Left Ventricular Systolic Diameter (p<0.0001), End Systolic Volume (p<0.0001), End Diastolic Volume (p<0.0001), Left Ventricular Mass Index (p<0.0001) and Left Ventricular Volume and Left Ventricular Mass Index ratio (p<0.0001). Analyzing patients with AS the indices who showed differences: (The ratio of mitral velocity to early diastolic velocity of the mitral annulus) E/E (p=0.0379)(Isovolumetric Relaxation Time)(p=0.0072) IRT, Diference between the pulmonary A wave duration and mitral A duration (p=0.0176), Left Atrial Sistolic Volume (p=0.0242), Left Atrial Systolic Volume Index (p=0.0237), Left Atrial Ejection Fraction (p=0.0339) Left Ventricular Diastolic Diameter (p=0.0002), Left Ventricular Systolic Diameter (p=0.0085), End Diastolic Volume (LVEDV) (p=0.0194), Left ventricular Mass Index(p<0.0001), Left Ventricular Volume and Mass Index Ratio (p<0.0001). CONCLUSIONS: As we studied diastolic function we have verified significant statistic variation in aortic regurgitation and aortic stenosis comparing before and after aortic valve replacement. Likewise we have seen there is correlation between NTproBNP and echocardiographic variables that show diastolic dysfunction.

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Auffret, Vincent. "Aide à la décision pour le remplacement valvulaire aortique percutané." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B035.

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La sténose aortique serrée est la valvulopathie acquise de l’adulte la plus fréquente affectant jusqu’à 10% des octogénaires. Sa prise en charge percutanée est en plein essor et confronte les cliniciens à des problèmes nouveaux constituant un champ de recherche important. Notre travail s’inscrit dans le cadre des gestes médico-chirurgicaux assistés par ordinateur et vise à proposer des solutions d’aide à la décision basées sur l’assistance informatique. Cette Thèse est ainsi composée de 4 parties. Une première partie porte sur la problématique médicale dans laquelle s’inscrit le remplacement valvulaire aortique percutané (TAVI) ainsi que le contexte du TAVI en France et présente un article évaluant l’évolution des caractéristiques des patients et des procédures à l’échelle nationale entre 2010 et 2015 dans les registres nationaux FRANCE 2 et FRANCE TAVI. Ce premier chapitre identifie des problématiques médicales auxquelles les opérateurs sont confrontés au quotidien notamment la sélection optimale des candidats et la minimisation des complications de la procédure dans le contexte d’une réduction du profil de risque des patients traités. La seconde partie s’intéresse à l’étude de populations, par des méthodes statistiques classiques, pour établir des facteurs prédictifs de résultats du TAVI ou de survenue d’une complication donnée afin d’aider le clinicien dans sa planification de la procédure. Cette partie est articulée autour de 3 articles portant sur les facteurs prédictifs d’accidents vasculaires cérébraux, les troubles conductifs et les facteurs prédictifs de « mauvais résultats » après TAVI. Nous démontrons l’intérêt de ce type d’analyse qui resteront nécessaires à l’avenir mais abordons également leurs limites qui expliquent pourquoi d’autres pistes doivent être explorées pour stocker, trier, restituer les informations pertinentes à l’opérateur voire les augmenter pour faciliter ses décisions notamment en préopératoire.L’objet de la 3ème partie est d’aborder un système d’aide à la décision par ordinateur de type « case-based reasoning » (CBR) qui pourrait tirer bénéfice de l’identification de ces facteurs pronostiques et à terme les intégrer dans une interface globale et ergonomique d’aide à la décision. Nous avons travaillé dans le cadre du projet européen H2020 EurValve sur l’élaboration d’un CBR dont la problématique se concentre pour l’instant sur le choix optimal de la voie d’abord, du type et de la taille de prothèse. Notre travail s’est concentré sur une étape analytique de la conception de ce type de système portant sur l’étude et l’amélioration de la mesure de similarité utilisée pour rapprocher le cas à traiter (problème) de ses plus proches voisins (cas déjà traités et leur « solution » thérapeutique). Enfin, une dernière partie porte sur l’augmentation des informations disponibles pour l’aide à la décision en préopératoire par la simulation numérique spécifique patient. Après un état de l’art des méthodes utilisées dans le domaine du TAVI, nous avons travaillé à l’élaboration et au paramétrage d’un modèle de simulation de l’insertion du guide rigide dans le ventricule gauche (une étape de la procédure qui peut conditionner le positionnement de la prothèse et donc le résultat final). Afin de réaliser une première validation de cette simulation exploitant l’imagerie tomodensitométrique 3D préopératoire, l’approche proposée repose sur l’extraction de la région d’intérêt dans le volume 3D (segmentation) et sa mise en correspondance avec l’imagerie fluoroscopique 2D peropératoire par le biais d’un recalage 3D/2D. Nos travaux sur ces méthodes de traitement de l’image nécessaires à la mise en œuvre et la validation de notre stratégie de simulation sont discutés dans cette partie. Enfin nous présentons une application clinique potentielle du modèle de simulation portant sur l’influence de la forme du guide et de ses conditions d’insertion sur sa stabilité et les forces de pression s’exerçant sur le ventricule gauche Aortic stenosis represents the most frequent acquired valvular heart disease, affecting up to 10% of octogenarians. Transcatheter aortic valve implantation (TAVI) is booming and confronts clinicians with new issues that constitute a major field of research. Our work falls within the framework of computer-assisted medico-surgical interventions, and aims at proposing computer-assisted decision support systems. The present Thesis is composed of four parts. The first part focuses on the medical problematic surrounding TAVI, as well as the current French TAVI field on the basis of an article describing temporal trends in patients’ and procedural’s characteristics from 2010 to 2015 in the FRANCE 2 and FRANCE TAVI nationwide registries. This first part identifies medical issues that operators currently face, especially the optimal selection of TAVI candidates, and the reduction of procedural complications within the current trends towards treatment of patients with lower baseline surgical-risk profile. The second part deal with population-based studies, through standard statistical methods, to identify predictors of TAVI outcomes or selected procedural complications in order to facilitate procedural planning. Three articles compose this part. The first focuses on predictors of short-term cerebrovascular events post-TAVI, the second deals with conduction disturbances post-TAVI while the third aims at identifying predictors of global poor outcomes. We demonstrate the benefits of these analyses, which will remain necessary in the future, but also address their limitations, which support the use of new methods to store, sort, retrieve, and even augment relevant information to facilitate operators’ decision, especially at the pre-procedural step.The purpose of Part 3 is to address a case-based reasoning (CBR) decision-support system that could benefit from the identification of these prognostic factors and ultimately integrate them into a global and ergonomic interface for decision support. We have worked in the framework of the European project H2020 EurValve on the development of a CBR whose problematic is,for the time being, limited to the optimal choice of the approach, type and size of prosthesis. Our work focused on an analytical step in the design of this type of system dealing with the study and improvement of the similarity measure used to identify nearest neighbours (previously treated cases and their therapeutic "solution") of the current problem (case which clinicians are planning to treat). Finally, the last part focuses on increasing the information available for preoperative decision support through patient-specific numerical simulation. After a state of the art of the methods used in the field of TAVI, we worked on the elaboration and parameterization of a simulation model of the insertion of the stiff guidewire in the left ventricle (one of the first steps of the procedure that can condition the positioning of the prosthesis and thus the final result). In order to perform a first validation of this patient-specific simulation using preoperative 3D CT imaging, the proposed approach is based on the extraction of the region of interest in the 3D volume (segmentation) and its mapping to intraoperative 2D fluoroscopy through 3D / 2D registration. Our work on these image processing methods needed to implement and validate our simulation strategy is also discussed in this section. Finally, we present a potential clinical application of the simulation model regarding the influence of the shape of the guide and its insertion conditions on its stability and the pressure forces exerted on the left ventricle

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Zuo, Heng. "3D Multi-Physics MRI-Based Human Right Ventricle Models for Patients with repaired Tetralogy of Fallot: Cardiac Mechanical Analysis and Surgical Outcome Prediction." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/478.

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Introduction. Computational modelling has been used widely in biological and clinical applications, but relatively less in surgical design and optimization. Magnetic resonance image (MRI)-based right ventricle (RV) models were introduced for patients with repaired Tetralogy of Fallot (rTOF) to assess ventricle cardiac function, and to identify morphological and mechanical parameters which can be used to predict and optimize post-surgery cardiac outcome. Tetralogy of Fallot is a common congenital heart defect which includes a ventricular septal defect and severe right ventricular outflow obstruction, account for the majority of cases with late onset RV failure. The current surgical approach for the patients with repaired ToF including pulmonary valve replacement/insertion (PVR) has yielded mixed results. It is of great interest to identify parameters which may be used to predict surgical cardiac function outcome after PVR. Data, Model, and Methods. Cardiac Magnetic Resonance (CMR) data from 20 healthy volunteers (11 males, mean year : 22.8) and 56 TOF patients (37 males, mean year : 25.3) were provided by Children's Hospital - Boston, Harvard Medical School from our NIH-funded project (R01 HL089269). RV wall thickness (WT), circumferential and longitudinal curvature (C-cur and L-cur), surface area (SA) and surface to volume ratio (SVR) were obtained based on CMR data for morphological analysis. 6 healthy volunteers and 16 TOF patients were chosen to construct 3D computational models for mechanical analysis. The 3D CMR-based RV/LV/Patch combination models included a) isotropic and anisotropic material properties, b) myocardial fiber orientation, c) active contraction with two zero-load geometries, and d) fluid-structure interactions. The models were used to obtain the assessment for RV mechanical conditions, which might be helpful for PVR surgical outcome prediction. All the computational models were built and solved in a commercial finite element software ADINA. Statistical methods including Linear Mixed- effort Method and Logistical regression were used in the morphological and mechanical analysis to find out potential indicators for predicting PVR outcome from the morphological and mechanical parameters. Results. In morphological analysis, statistically significant differences were found in RV SA and SVR between better-outcome patient group (BPG) and worse-outcome patient group (WPG). At begin of ejection, mean RV SA of BPG was 13.6% lower than that from WPG (241.1 cm2 v.s. 279.0 cm2, p =0.0161). Mean RV SVR of BPG was 13.1% lower than that from WPG (1.26 cm2/ml v.s. 1.45 cm2/ml, p =0.0271). Similar results were also found in RV SA and SVR at begin of filling. Furthermore, RV EF change from pre- to post-PVR were found negatively correlated with RV SA and SVR. In mechanical analysis, 22 structure-only models with one zero-load geometry (1G) were constructed to obtain stress/strain distributions. Stress-P1 from BPG was found to be closer to that from HG, compared to Stress- P1 of WPG. At the beginning of ejection, mean Stress-P1 of BPG was only 6.8% higher than that from healthy group (p =0.6889), while average Stress-P1 of WPG was 84.1% higher than that of healthy group (p =0.0418). Similar results were also found at begin of filling. The results suggested that comparing patients' RV stress values with healthy RV stress values may help identify patients with possible better outcome. The models with two zero-load geometries (2G models) and FSI models were also constructed. Their numerical results indicated that 2G models can provide end-ejection and end-filling results which were not available in 1G models, and FSI models can provide flow velocity, pressure and shear stress information which lacked in structure-only models (1G and 2G models). Conclusion. In vivo image-based 3D patient- specific computational models could lead to considerable potential gain not only in surgical design and outcome prediction, but also in understanding the mechanisms of RV failure for patients with repaired TOF.

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Dissertations / Theses on the topic 'Surgical aortic valve replacement'

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