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.

Transcatheter aortic valve implantation (TAVI) is an effective alternative treatment option for patients with severe aortic stenosis, who are at a high risk for conventional surgical aortic valve replacement or considered inoperable. Despite the short- and mid-term survival benefits of TAVI, adverse clinical events, such as paravalvular leak, aortic rupture, and coronary occlusion, have been reported extensively. Many of these adverse events can be explained from the biomechanics perspective. Therefore, an in-depth understanding of biomechanical interaction between the device and native tissue is critical to the success of TAVI. The objective of this thesis was to investigate the biomechanics involved in the TAVI procedure using patient-specific finite element (FE) simulations. Patient-specific FE models of the aortic roots were reconstructed using pre-procedural multi-slice computed tomography images. The models incorporated aged human aortic material properties with material failure criteria obtained from mechanical tests, and realistic stent expansion methods. TAV deployment and tissue-device interaction were simulated; and the simulation results were compared to the clinical observations. Additionally, parametric studies were conducted to examine the influence of the model input on TAVI simulation results and subsequently the potential clinical complications such as paravalvular leak, annular rupture, and coronary artery occlusion. The methodology presented in this thesis could be potentially utilized to develop valuable pre-procedural planning tools to evaluate device performance for TAVI and eventually improve clinical outcomes.

There is growing interest in using large-scale observational data collected through national disease registries to develop clinical prediction models (CPMs) that use the experiences of past patients to make predictions about risks of outcome in future patients. CPMs are often developed in isolation across different populations, with repetitive de novo development a common modelling strategy. However, this fails to utilise all available information and does not respond to changes in health processes through time/space. Using the UK transcatheter aortic valve implantation (TAVI) registry as motivation, this thesis aimed to develop methods that improve the development of CPMs within local populations. Three research questions (RQs) were considered: (1) what are the challenges of mortality risk prediction in TAVI due to changes in procedure knowledge and the patient population? (2) Can we use a combination of baseline patient characteristics to predict the risk of mortality post TAVI? (3) How can we exploit multi-dimensional information about patients to inform clinical decision-making at a local-level? Chapter 2 demonstrates potential to simplify the procedure by removing pre-dilation of the aortic valve, thereby altering the underlying treatment pathway, and Chapter 3 shows that mortality rates from registries should be reported in the context of the underlying patient population. Despite Chapter 2 and 3 presenting potential challenges to TAVI risk prediction (RQ 1), CPMs are fundamental to support benchmarking/audit analyses. To this end, Chapter 4 found that the performance of existing TAVI CPMs was inadequate for use in UK patients. Through the discovery of new risk factors (e.g. frailty) in Chapter 5, the thesis derived a UK-TAVI CPM for audit analyses within the UK cohort (Chapter 6). While Chapters 4-6 present the classic framework of CPM development (RQ 2), this cannot overcome the challenges of mortality prediction in the TAVI setting (RQ 1) and is not suited to support local healthcare decision-making (RQ 3). Thus, Chapter 7 found that local model development could be supported through aggregating existing models rather than re-development. Existing methods of model aggregation were extended in Chapter 8 to allow prior research and new data to be utilised within the modelling strategy; application of the herein derived method to the UK TAVI registry indicated that it could facilitate the choice between model aggregation and de novo CPM derivation. Generally, this thesis has the potential to improve the implementation of CPMs within local populations by moving away from the iterative process of re-development. Practically, the thesis derived a UK-TAVI CPM for audit analyses, using classic and novel methodology.

Objectives To compare incidence of aortic regurgitation (AR), paravalvular AR and valvular performance with Doppler hemodynamic parameters following transcatheter aortic valve replacement (TAVR) with Edwards valve (EV) versus CoreValve (CV). Currently, there are scarce data on post-TAVR echocardiographic outcomes comparing EV and CV. Methods PubMed and the Cochrane Center Register of Controlled Trials were searched through May 2015. Twenty studies (n = 11,244) comparing TAVR procedure that used EV (n = 6445) and CV (n = 4799) were included. End points were post-TAVR moderate to severe AR and paravalvular AR, effective orifice area (EOA), mean trans-aortic pressure gradient (MPG), peak trans-aortic pressure gradient (PPG) and left ventricular ejection fraction (LVEF). The mean difference (MD) or relative risk (RR) with 95% confidence interval (CI) was computed and p < 0.05 was considered as a level of significance. Results Moderate to severe AR and paravalvular AR were significantly lower in EV group (RR: 0.57, CI: 0.52–0.63, p < 0.00001 and RR: 0.40, CI: 0.25–0.63, p < 0.0001 respectively) compared to CV group. EOA and PPG were not significantly different between EV and CV groups. MPG was significantly lower among patients in CV group (MD: 1.08, CI: 0.05–2.10, p = 0.04). LVEF was significantly higher in patients in EV group (MD: 2.26, CI: 0.77–3.74, p = 0.03). Conclusions This study showed CV is associated with higher incidence of post-TAVR moderate to severe paravalvular AR. Echocardiographic valvular performance measures (MPG, LVEF) showed minimal but significant difference, which may not be clinically significant.

No description available.

The overall aim of this thesis is to explore experiences and self-reported outcomes from Transcatheter Aortic Valve Implantation, TAVI, among people with severe aortic stenosis. The thesis includes four studies. Study I-II are based on interviews performed the day before TAVI and Qualitative Concept Analysis was used for analysis. Study III is based on interviews at six months’ follow-up and Grounded Theory was used for analysis. Study IV is quantitative and based on questionnaires at baseline and at six months’ follow-up. Nonparametric, descriptive statistics were used for the analysis. Study I described the vulnerable situation for patients with severe aortic stenosis before TAVI. They were facing death and at the same time struggling to cope with their symptoms and to maintain independent. TAVI offered hope but also caused uncertainty about the new method. Study II focused on the patients’ decision-making process. Three patterns were identified; ambivalent, obedient, and reconciled. The ambivalent patient is unsure of the value of treatment and aware of the risks; the obedient patient is unsure of the value of one's own decision and wants to leave the decision to others; the reconciled patient has reached a point where there is no choice anymore and is always sure that the decision to undergo TAVI is right. Study III offered a deeper understanding of the TAVI trajectory. A journey of balancing between hope and life-struggle was the core category of the analysis. Before TAVI patients felt threatened, but also experienced hope. The rehabilitation phase was described as demanding and depressing or surprisingly simple. At the six months’ followup patients described being pleased to return to life, however, many were still struggling with limitations. Study IV focused on quantifying the symptom burden, function and health related quality of life before and after TAVI. The results were reflected against that of patients treated with open surgery. Self-rated function and health related quality of life increased and symptoms were reduced at follow-up, but breathlessness and fatigue were still common. Conclusively, TAVI patients are struggling with limitations, both because of their comorbidities and because of their valve disease which also poses a threat to their lives. TAVI gives an opportunity to survive, to stay independent and to increase quality of life. To feel and preserve hope is essential for patients’ wellbeing, both before and during the recovery process.

No description available.

Transcatheter aortic valve replacement in the setting of failed surgical bioprosthesis (valve-in-valve) is a valuable option for patients with bioprosthetic aortic stenosis or regurgitation who are deemed high risk for repeat open heart surgery. Although the procedure is successful with proper preprocedural assessment, instances of left main (LM) coronary artery ostium obstruction have been documented. We present a case of LM coronary obstruction in the immediate postoperative period following implantation of a 20-mm Edwards Sapien 3 valve inside the degenerated 21-mm Mitroflow bioprosthesis stenosis, which was treated with double stenting alongside the Edwards Sapien 3 valve creating a channel (“neo left main”) that extended from mid-LM to the upper margin of the Edwards Sapien 3 valve. Although valve-in-valve in a Mitroflow degenerated bioprosthesis is a relatively safe procedure, 2 or more stents may be necessary to scaffold a channel to the coronary arteries between Edwards Sapien 3 prosthesis and aorta in the event of a coronary obstruction.

Objective: Studies have shown that iodinated radiocontrast use is associated with acute renal failure especially in the presence of chronic kidney disease and multiple factors modulate this risk. The purpose of this meta-analysis is to compare the incidence of renal failure requiring hemodialysis between transfemoral (TF) and transapical (TA) transcatheter aortic valve replacement using the Edwards valve. Methods: The PubMed database was searched from January 2000 through December 2014. A total of 10 studies (n = 2,459) comparing TF (n = 1,268) and TA (n = 1,191) TAVR procedures using the Edwards valve were included. Variables of interest were baseline logistic EuroSCORE, prevalence of diabetes mellitus, hypertension, peripheral arterial disease, chronic kidney disease and amount of contrast used. The primary endpoint was incidence of renal failure requiring hemodialysis. The odds ratio and 95% CI were computed and P < 0.05 was considered as the level of significance. Results: The logistic EuroSCORE was significantly higher in TA compared to TF (P = 0.001) TAVR. The amount of contrast (mL) used was significantly higher in the TF group compared to the TA group (mean difference: 36.9, CI: 25.7-48.1, P < 0.001). The incidence of hemodialysis following the procedure was significantly higher in the TA group compared to TF group (odds ratio = 4.3, CI: 2.4-7.8, P < 0.00001). Conclusions: This meta-analysis suggests that despite the lower amount of contrast used in TA-TAVR, the incidence of renal failure requiring hemodialysis was higher with the Edwards valve. This suggests that the incidence of renal failure requiring hemodialysis after TAVR is associated with baseline comorbidities in the TA-TAVR group rather than the volume of contrast used.

Objectives: In patients with severe aortic stenosis who are at high risk for surgery, transcatheter aortic valve replacement (TAVR) has emerged as an alternative procedure using EV or CV. The objective of this meta-analysis is to compare 1-year mortality and major adverse cardiovascular and cerebrovascular events (MACCE) between Edwards valve (EV) and Medtronic CoreValve (CV). Methods: PubMed and the Cochrane Center Register of Controlled Trials were searched through December 2014. Twenty seven studies (n = 12,249) comparing TAVR procedure that used EV (n = 5745) and CV (n = 6504) were included. End points were procedural success rates, post-procedural mortality, myocardial infarction (MI), stroke, major bleeding, major vascular complications, incidence of new permanent pacemaker (PPM) placement and new left bundle branch block (LBBB). The odds ratio (OR) with 95% confidence interval (CI) was computed and p < 0.05 was considered for significance. Results: There were no significant differences between EV and CV for post-procedural in-hospital, 30-day and 1-year all-cause mortality rates (p = 0.53, 0.33 and 0.94 respectively), cardiovascular mortality (p = 0.61), stroke (p = 0.54), major bleeding (p = 0.25) and major vascular complications (p = 0.27). MI was significantly lower with EV compared to CV (OR: 0.56, CI: 0.35-0.89, p = 0.01). Placement of new PPM and new onset LBBB were significantly higher in CV compared to EV (OR: 3.35, CI: 2.96-3.79, p < 0.00001 and OR: 6.55, CI: 4.76-9.03, p < 0.00001 respectively). Conclusions: The results of our meta-analysis suggest that TAVR procedure using CV may be associated with a higher incidence of MI, new PPM placement, and new onset LBBB compared to EV. However, the type of valve placed does not affect mortality.