An up-to-date overview of the most recent transcatheter implantable aortic valve prostheses

The Interventional Imager: How Do We Train the Next Interventional Imagers?

With the increase in structural heart procedural volume, interventional imagers are required. Multiple imaging modalities exist to guide these procedures. With comprehensive understanding of pathology, anatomy, and procedures, an advanced imager plays an important role in the heart team. Imaging training is part of general cardiology fellowship. Current structures do not provide adequate procedural time to fill the role. Interested graduates pursue advanced training by either focusing on echocardiography and procedural imaging or multidetector computed tomography and cardiac magnetic resonance. This yields individuals with different expertise.

Emerging transcatheter heart valve technologies for severe aortic stenosis

INTRODUCTION

Transcatheter aortic valve implantation (TAVI) is the standard of care for selected patients with severe aortic stenosis, irrespective of the surgical risk. Over the last two decades of TAVI practice, multiple limitations were identified. In addition, the extension of TAVI into a wider patient spectrum created new challenges.

AREAS COVERED

This review provides an overview of emerging transcatheter heart valves (THVs) beyond the approved contemporary THVs for the treatment of aortic stenosis.

EXPERT OPINION

The incidence of degenerative aortic stenosis is expected to increase with more aging of the population. Therefore, TAVI needs to meet this increase in the number of patients indicated for aortic valve replacement alongside a wide and complex anatomical variability. An increasing number of Aortic THVs are available in the market. This includes upgraded iterations of contemporary devices and innovative devices developed by emerging manufacturers. The new devices aim for the reduction or elimination of undesirable outcomes like paravalvular leakage and conduction disturbances requiring permanent pacemaker implantation. Alternatively, emerging THVs should provide feasibility regarding yet unproven TAVI indications like Bicuspid aortic valve, aortic regurgitation, or very large anatomy. Furthermore, some of the emerging THVs are designed to tackle the long-term durability issue of biological valves.

Impact of nickel-titanium super-elastic material properties on the mechanical performance of self-expandable transcatheter aortic valves

Self-expandable transcatheter aortic valves (TAVs) elastically resume their initial shape when implanted without the need for balloon inflation by virtue of the nickel-titanium (NiTi) frame super-elastic properties. Experimental findings suggest that NiTi mechanical properties can vary markedly because of a strong dependence on the chemical composition and processing operations. In this context, this study presents a computational framework to investigate the impact of the NiTi super-elastic material properties on the TAV mechanical performance. Finite element (FE) analyses of TAV implantation were performed considering two different TAV frames and three idealized aortic root anatomies, evaluating the device mechanical response in terms of pullout force magnitude exerted by the TAV frame and peak maximum principal stress within the aortic root. The widely adopted NiTi constitute model by Auricchio and Taylor (1997) was used. A multi-parametric sensitivity analysis and a multi-objective optimization of the TAV mechanical performance were conducted in relation to the parameters of the NiTi constitutive model. The results highlighted that: five NiTi material model parameters (E_A, σ_tL^S, σ_tU^S, σ_tU^E and σ_cL^S) are significantly correlated with the FE outputs; the TAV frame geometry and aortic root anatomy have a marginal effect on the level of influence of each NiTi material parameter; NiTi alloy candidates with pareto-optimal characteristics in terms of TAV mechanical performance can be successfully identified. In conclusion, the proposed computational framework supports the TAV design phase, providing information on the relationship between the super-elastic behavior of the supplied NiTi alloys and the device mechanical response.

Next-generation tissue-engineered heart valves with repair, remodelling and regeneration capacity

Valvular heart disease is a major cause of morbidity and mortality worldwide. Surgical valve repair or replacement has been the standard of care for patients with valvular heart disease for many decades, but transcatheter heart valve therapy has revolutionized the field in the past 15 years. However, despite the tremendous technical evolution of transcatheter heart valves, to date, the clinically available heart valve prostheses for surgical and transcatheter replacement have considerable limitations. The design of next-generation tissue-engineered heart valves (TEHVs) with repair, remodelling and regenerative capacity can address these limitations, and TEHVs could become a promising therapeutic alternative for patients with valvular disease. In this Review, we present a comprehensive overview of current clinically adopted heart valve replacement options, with a focus on transcatheter prostheses. We discuss the various concepts of heart valve tissue engineering underlying the design of next-generation TEHVs, focusing on off-the-shelf technologies. We also summarize the latest preclinical and clinical evidence for the use of these TEHVs and describe the current scientific, regulatory and clinical challenges associated with the safe and broad clinical translation of this technology.

Bioprinting of radiopaque constructs for tissue engineering and understanding degradation behavior by use of Micro-CT

Bioprinting has emerged as a potential technique to fabricate tissue engineering constructs and in vitro models directly using living cells as a raw material for fabrication, conforming to the heterogeneity and architectural complexity of the tissues. In several of tissue engineering and in vitro disease modelling or surgical planning applications, it is desirable to have radiopaque constructs for monitoring and evaluation. In the present work, enhanced radiopaque constructs are generated by substituting Calcium ions with Barium ions for crosslinking of alginate hydrogels. The constructs are characterized for their structural integrity and followed by cell culture studies to evaluate their biocompatibility. This was followed by the radiopacity evaluation. The radiological images obtained by micro-CT technique was further applied to investigate the degradation behavior of the scaffolds. In conclusion, it is observed that barium crosslinking can provide a convenient means to obtain radiopaque constructs with potential for multi-faceted applications.

WorldwIde SurvEy on Clinical and Anatomical Factors Driving the Choice of Transcatheter Aortic Valve pRostheses

Background: Following the success of the first human transcatheter aortic valve replacement (TAVR) in 2002, multiple transcatheter heart valves (THVs) have become available. However, guidelines or expert consensus on how to optimize THV choice according to patients' anatomical and clinical characteristics is missing. This survey-based study aimed to identify patient-specific characteristics deemed important in the choice of THV type.

Methods and results: A web-based survey including 39 questions was completed by 71 experienced TAVR operators from 23 countries with a median TAVR volume of 88 procedures in the year prior to survey completion (IQR 61-180). The survey covered five topics: access, aortic annulus/leaflets, aortic root, left ventricular function and clinical characteristics. Factors with the most impact on THV choice were reported to be a calcified sinotubular junction, valve-in-valve procedure, annular dimension >575 mm², femoral diameter ≤ 5.0 mm, low coronary ostia, calcification at the annular level and/or protruding into the left ventricular outflow tract, and need for post TAVR PCI. Also, in case of off-label use of THVs to treat bicuspid aortic valve disease and isolated aortic regurgitation, the choice of THV type was reported to be important.

Conclusions: This survey-based study identifies key patient characteristics that impact THV selection. As such, we present a guide, based on current practice, of which THV types are best suited to these different patient-specific characteristics. A patient-tailored THV choice is likely to optimize TAVR outcomes.

Transcatheter aortic valve replacement: clinical safety and performance data

Introduction: Patients with severe aortic stenosis and regurgitation who are inoperable or at high-risk for surgery can be treated with transcatheter aortic valve replacement (TAVR). The aim of this study was to provide a comprehensive overview of the literature of TAVR and reported clinical and performance outcomes. Areas covered: A total of 16 devices, described in 204 articles describing clinical and performance outcomes, were included. The most frequently observed outcome was 30-day mortality, ranging between 0-23%. Other commonly reported clinical outcomes were 30-day stroke, ranging between 0-14.3% and pacemaker implantation, ranging from 0-44.9%. The most common valve performance outcome was aortic valve regurgitation, however, mostly reported at 7 days follow-up. Next to a follow-up period of 30 days, numerous articles reported outcomes at 6 months and 1 year. The numbers of articles describing outcomes with a longer follow-up as well as including intermediate and low-risk patients were limited. Expert commentary: This literature review provided a clear overview of the reported clinical and performance outcomes of TAVR devices. Despite the frequently used VARC-2 definitions, we identified a huge variation across studies. Future studies using standardized definitions of study set-ups and outcomes are essential and might lead to better insights of TAVR.

CT and MR imaging prior to transcatheter aortic valve implantation: standardisation of scanning protocols, measurements and reporting-a consensus document by the European Society of Cardiovascular Radiology (ESCR)

Abstract

Transcatheter aortic valve replacement (TAVR) is a minimally invasive alternative to conventional aortic valve replacement in symptomatic patients with severe aortic stenosis and contraindications to surgery. The procedure has shown to improve patient’s quality of life and prolong short- and mid-term survival in high-risk individuals, becoming a widely accepted therapeutic option which has been integrated into current clinical guidelines for the management of valvular heart disease. Nevertheless, not every patient at high-risk for surgery is a good candidate for TAVR. Besides clinical selection, which is usually established by the Heart Team, certain technical and anatomic criteria must be met as, unlike in surgical valve replacement, annular sizing is not performed under direct surgical evaluation but on the basis of non-invasive imaging findings. Present consensus document was outlined by a working group of researchers from the European Society of Cardiovascular Radiology (ESCR) and aims to provide guidance on the utilisation of CT and MR imaging prior to TAVR. Particular relevance is given to the technical requirements and standardisation of the scanning protocols which have to be tailored to the remarkable variability of the scanners currently utilised in clinical practice; recommendations regarding all required pre-procedural measurements and medical reporting standardisation have been also outlined, in order to ensure quality and consistency of reported data and terminology.

Key Points

• To provide a reference document for CT and MR acquisition techniques, taking into account the significant technological variation of available scanners.

• To review all relevant measurements that are required and define a step-by-step guided approach for the measurements of different structures implicated in the procedure.

• To propose a CT/MR reporting template to assist in consistent communication between various sites and specialists involved in the procedural planning.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06357-8) contains supplementary material, which is available to authorized users.

Comparison of Causes and Associated Costs of 30-Day Readmission of Transcatheter Implantation Versus Surgical Aortic Valve Replacement in the United States (A National Readmission Database Study)

Our current knowledge about comparative differences in 30-day readmissions and the impact of readmissions on overall costs after transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) is largely derived from clinical trials. The objectives of this study were to compare readmissions and costs for TAVI and SAVR in a nationally representative population-based sample. The Healthcare Cost and Utilization Project's National Readmission Database was used for the study. Hierarchical multivariable regression analyses were used to examine differences in the propensity score 1:1 matched cohort. The matched cohort included 4,682 patients who survived index procedures done from January through November 2013. Compared with SAVR, the rate of 30-day readmission was not significantly different for endovascular TAVI (16% vs 18%; p = 0.19); and was higher for the transapical TAVI (22% vs 17%; p <0.01) group. The 30-day cumulative costs were higher for the 2 endovascular TAVI ($51,025 vs $46,228; p = 0.03) and transapical TAVI ($59,575 vs $45,792; p <0.01). In multivariable analyses, the risk of 30-day readmission was similar for endovascular TAVI (odds ratio [OR] 0.93; 95% confidence interval [CI] 0.78 to 1.12) and was 27% higher for transapical TAVI (OR 1.27; 95% CI 1.02 to 1.57). Cumulative costs (index plus readmission costs) were 13% (β 0.13; 95% CI 0.10 to 0.15) and 19% (β 0.19; 95% CI 0.16 to 0.23) higher for the endovascular TAVI and transapical TAVI, respectively. In conclusion, the rate of readmissions was similar for endovascular TAVI and SAVR but the costs were 26% higher for TAVI than for SAVR.

Transcatheter heart valve in valve implantation with Edwards SAPIEN bioprosthetic valve for different degenerated bioprosthetic valve positions (First Iranian ViV report with mid-term follow up)

Introduction: After early successful experience with transcatheter aortic valve replacement (TAVR), concept of transcatheter implantation of a new valve within a failing bioprosthetic valve emerged. Valve-in-valve (ViV) implantation seems to be a simpler option for high risk surgical patients.

Methods: We performed five ViV procedures in different valve positions. We included patients with failing bioprosthetic valves with high surgical risk due to concomitant comorbidities. We performed 2 transapical ViV procedures for failing mitral bioprosthetic valves, 1 transfemoral procedure for failing pulmonary valve and 2 transfemoral ViV implantation for failing tricuspid bioprosthetic valves.

Results: The procedures were successfully completed in all 5 cases with initial excellent fluoroscopic and echocardiographic verification. There was no valve embolization or paravalvular leakage in any of the cases. Transcatheter valve function was appropriate with echocardiography. Post procedural clinical adverse events like pleural effusion and transient ischemic attack were managed successfully. In midterm follow up all cases remained in appropriate functional class except from the transcatheter pulmonary valve which became moderately stenotic and regurgitant.

Conclusion: As the first Iranian all-comers case series with midterm follow up for ViV implantation, we had no mortality. Interestingly none of our patients had neurologic sequelae after the procedure. Midterm follow up for our patients was acceptable with good functional class and appropriate echocardiographic findings. Due to high surgical risk of the redo procedure after failing of a bioprosthetic valve especially in elderly patients with comorbidities, ViV implantation would be a good alternative to surgery for this high risk group.