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

Over the past decade transcatheter aortic valve implantation (TAVI) has evolved towards the routine therapy for high-risk patients with severe aortic valve stenosis. Technical refinements in TAVI are rapidly evolving with a simultaneous expansion of the number of available devices. This review will present an overview of the current status of development of TAVI-prostheses; describes the technical features and applicability of each device and the clinical data available.

A New Transcatheter Aortic Valve Replacement System for Predominant Aortic Regurgitation Implantation of the J-Valve and Early Outcome

OBJECTIVES

This study introduces a newly designed transcatheter aortic valve system, the J-Valve system, and evaluates its application in patients with predominant aortic regurgitation without significant valve calcification. We also report the early results of one of the first series of transapical implantations of this device and aim to offer guidance on the technical aspects of the procedure.

BACKGROUND

Transcatheter aortic valve replacement (TAVR) has been widely used in high-risk patients for surgical aortic valve replacement. However, the majority of the TAVR devices were designed for aortic valve stenosis with significant valve calcification.

METHODS

Six patients with native aortic regurgitation without significant valve calcification (age, 61 to 83 years; mean age, 75.50 ± 8.14 years) underwent transapical implantation of the J-Valve prosthesis (JieCheng Medical Technology Co., Ltd., Suzhou, China), a self-expandable porcine valve, in the aortic position at our institution. All patients were considered to be prohibitive or high risk for surgical valve replacement (logistic EuroSCORE [European System for Cardiac Operative Risk Evaluation], 22.15% to 44.44%; mean, 29.32 ± 7.70%) after evaluation by an interdisciplinary heart team. Procedural and clinical outcomes were analyzed.

RESULTS

Implantations were successful in all patients. During the follow-up period (from 31 days to 186 days, mean follow-up was 110.00 ± 77.944 days), only 1 patient had trivial prosthetic valve regurgitation, and none of these patients had paravalvular leak of more than mild grade. There were no major post-operative complications or mortality during the follow-up.

CONCLUSIONS

Our study demonstrated the feasibility of transapical implantation of the J-Valve system in high-risk patients with predominant aortic regurgitation.

Balloon- or Self-Expandable TAVI: Clinical Equipoise?

Transcatheter aortic valve implantation (TAVI) has become an effective treatment option for patients with severe aortic stenosis and high surgical risk or contraindications for surgical aortic valve replacement. Most of the currently available prostheses employ either balloon-expandable or self-expandable designs. Presently, there is a paucity of data directly comparing these two widely used prosthesis types. Forthcoming trials will reveal whether newer designs of both technologies translate into fewer complications and better outcomes, with expansion of TAVI indications. This manuscript reviews features and clinical outcomes of balloon- and self-expanding prostheses, summarising current data from registries and trials.

Real-time magnetic resonance-guided aortic valve replacement using Engager valve

PURPOSE

New-generation stented bioprostheses coupled with better imaging modalities are expanding the clinical utility of transcatheter aortic valve replacement (TAVR). This study aimed at evaluating the feasibility of real-time cardiovascular magnetic resonance (rtCMR) -guided TAVR using the Medtronic Engager aortic valve system in a preclinical model.

DESCRIPTION

The Engager delivery device was slightly modified to make it CMR-compatible. Ten Yucatan swine underwent rtCMR-guided transapical TAVR. Postplacement phase-contrast and first-pass perfusion CMR sequences were used to evaluate for aortic regurgitation and myocardial perfusion, respectively.

EVALUATION

Real-time CMR provided excellent visualization of cardiac anatomy during TAVR. Nine of 10 animals had proper valve placement in the aortic annulus as determined by CMR and confirmed by necropsy inspection. Postplacement phase-contrast scans confirmed no intravalvular or paravalvular leaks. Perfusion scans demonstrated sufficient coronary flow. Roentgenographs confirmed proper placement of the prostheses.

CONCLUSIONS

The Engager valve can be implanted transapically under rtCMR guidance with a modified, CMR-compatible delivery device in a preclinical model. Cardiovascular magnetic resonance allowed for accurate preplacement evaluation, real-time guidance, and postplacement functional assessment.

Single-Center Experience and Short-term Outcome with the JenaValve: A Second-Generation Transapical Transcatheter Aortic Valve Implantation Device

Objective

We present the post-CE(Conformité Européenne)-mark single-center implantation experience and short-term outcome with the second-generation transapical JenaValve transcatheter aortic valve implantation system.

Methods

Patients [N = 27; 9 women; mean (SD) age, 80.3 (5.5) years] were operated on between November 2011 and August 2012. Via a transapical approach, the valve was positioned, in some cases, repositioned, and finally implanted. All data were collected during the hospital stay.

Results

The implantation success rate was 100%; the mean (SD) operation time was 124.7 (43.2) minutes; and the size of the implanted prosthesis was 23 mm (n = 6), 25 mm (n = 14), and 27 mm (n = 7). The in-hospital major adverse cardiac and cerebrovascular events were as follows: intraoperative resuscitation with subsequent aortic rupture (n = 1), postoperative hemorrhage needing revision (n = 1), myocardial infarction (n = 1), atrioventricular block needing a definitive pacemaker (n = 1), new-onset renal failure needing hemodialysis (n = 1), and stroke (n = 1). The 30-day mortality was 11.1% (n = 3). The mean (SD) intensive care unit/total stay was 2.2 (1.7)/11.7 (7.9) days. Postoperative echocardiography [day 6.7 (4.8)] revealed residual para-valvular leakage of trace to grade 1 in 12 patients (44.5%) and no leakage in 15 patients, with a mean (SD) transvalvular pressure gradient of 11.6 (5.6) mm Hg with significant reduction by 36.0 (17.7) mm Hg ( P = 0.0001, Wilcoxon signed rank test).

Conclusions

This second-generation repositionable transcatheter aortic valve implantation device could safely and successfully be implanted with a fast learning curve, significant reduction in pressure gradients, overall clinical improvement at discharge, as well as an acceptable morbidity and mortality rate in this highest-risk patient cohort.

Evolution of Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement emerged ≈20 years ago and changed the landscape of structural interventional cardiology. The first experiments in animal models provided proofs of the concept and the substrate for the first percutaneous valve implantation in patients. The initial promising results in a clinical setting drew the attention of the industry and of the scientific community, and an effort was made for the past 12 years to address the limitations of the technology, facilitate the procedure, minimize the risk of complications, and broaden the applications of transcatheter aortic valve replacement. This article reviews the evolution of transcatheter aortic valve replacement, presents the first steps in this field, cites the evidence from registries and clinical trials, highlights the limitations of this treatment, and discusses the future perspectives and the developments proposed to address the current pitfalls.

Self-expanding prostheses for transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) has emerged as an alternative to surgical aortic valve replacement in patients who are considered high surgical risk or inoperable due to advanced age and comorbidities. Randomized trial and registry data have demonstrated the safety and efficacy of TAVR in such patients. Currently available transcatheter heart valves (THVs) employ either balloon-expandable or self-expanding designs, and several new designs have shown promising early results. Differences in valve design may offer specific advantages for accurate deployment and minimizing complications. This article reviews several designs of self-expanding THVs that are currently available or have undergone successful implantation in humans. Additional studies are required to compare the relative performance of these devices.

New devices for TAVI: technologies and initial clinical experiences

Treatment of aortic stenosis in high-risk surgical patients has been modified in the past 10 years owing to the introduction of transcatheter aortic valve implantation (TAVI). Several issues affecting outcomes with implantation of the first-generation TAVI devices remain unresolved, including haemorrhagic and vascular complications, neurological events, rhythm disturbances, and paravalvular leakage. Further technological improvements are, therefore, required before the indications for TAVI can be extended to young and low-risk patients with aortic stenosis. Many new-generation TAVI devices are currently in the early stages of clinical evaluation. Modifications in the new devices include the ability to reposition the valve before final deployment, features to reduce paravalvular leakage, and the introduction of low-profile delivery systems. The aim of this Review is to provide an overview of the new-generation transcatheter valvular technologies, including initial clinical reports.

Intermediate follow-up results from the multicenter engager European pivotal trial

BACKGROUND

Optimal transcatheter aortic valve (TAVI) results require accurate valve positioning, including anatomically correct orientation and secure fixation within the aortic annulus, thereby potentially decreasing paravalvular regurgitation. The new Engager (Medtronic 3F Therapeutics, Santa Ana, CA) transapical valve system captures the native leaflets for sealing and allows for tactile feedback during valve placement. We report initial safety and performance outcomes of the Engager system through 6 months in patients with severe aortic valve stenosis at high risk for surgical aortic valve replacement.

METHODS

An interim analysis was performed on the first 61 enrolled September 2011 through May 2012. Inclusion criteria comprised severe aortic stenosis, New York Heart Association functional class of II or greater, logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) of 20% or greater, or contraindication to surgical aortic valve replacement. The primary endpoint was all-cause mortality at 30 days. Patients were evaluated 24 to 48 hours post-procedure, at hospital discharge, 30 days and 6 months. Follow-up is planned annually through five years.

RESULTS

Baseline characteristics for the 61 patients were mean age 81.9 ± 4.4 years, 62.3% female, 88.5% New York Heart Association class III/IV, 52.5% coronary artery disease, and 54.2% extracardiac arteriopathy. For all of the attempted implantations (n = 60), the Engager prosthesis was positioned in the correct anatomic position without conversions to surgery, second valve implantation, device malposition, aortic annular rupture, or coronary obstruction. All-cause mortality was 9.9% at 30 days and 16.9% at 6 months. The baseline mean aortic valve gradient was 43.7 ± 16.7 mm Hg and 11.5 ± 5.0 mm Hg at 30 days, and showed similar reduction at 6 months (13.9 ± 6.2 mm Hg). There was no paravalvular regurgitation greater than mild through 6 months.

CONCLUSIONS

Early postoperative results support implantation success and valve safety. Analysis for 6 month outcomes shows stable hemodynamic performance and clinical outcome. (Transapical Implantation of the Medtronic Engager Transcatheter Aortic Valve Implantation System-the Engager European Pivotal Trial; NCT01348438).

Outcome of Patients Treated with Engager Transapical Aortic Valve Implantation

Objective

The aim of this study was to investigate the short-term and midterm outcome of the Engager transcatheter aortic valve implantation (TAVI) system, a transapical self-expanding valve device with anatomic orientation.

Methods

Transapical aortic valve implantation with the Engager valve prosthesis was performed in 10 patients. Endpoints were defined according to the Valve Academic Research Consortium recommendations for reporting outcomes of TAVI in clinical trials. Follow-up has been completed after 30 days and 1 year.

Results

All patients underwent the implantation procedure successfully. No device-related or delivery system–related complications were observed. One patient died of non–device-related reasons at postoperative day 23 in multiorgan failure. At 30-day follow-up, no more than mild transvalvular and paravalvular aortic regurgitation were seen. After 1 year, no transvalvular regurgitation was observed as assessed by transthoracic echocardiography. None of the patients had more than mild paravalvular leakage. The mean ± SD gradient was 15.3 ± 4.2 mm Hg. New York Heart Association class decreased one degree in mean and sustained until 1-year follow-up. No more patients died until 1-year follow-up.

Conclusions

Application of the Engager TAVI system is safe and reliable. Prosthesis deployment in an anatomically correct position was facilitated by the design of the valve prosthesis and successful in all patients. No device-related or delivery system–related complications occurred. Procedural, short-term, and midterm results up to 1 year concerning the aortic valve performance are promising, with stable mean gradients and low rates of even mild regurgitation.

Transcatheter aortic valve implantation (TAVI): valve design and evolution

The efficacy of transcatheter aortic valve implantation (TAVI) in high surgical risk and inoperable patients with severe aortic stenosis (AS) is rapidly gaining credibility with an ever-expanding body of supporting evidence. The potential of TAVI to be a treatment option for a significant cohort of patients with aortic stenosis has fuelled a drive for the optimum device and resulted in exponential advances in the technology with a focus on adverse event minimization and procedural simplification. Consequently, a plethora of new transcatheter valve choices are now available for clinical study or in the pipeline. The evaluation of past, current and emerging devices allows for an appreciation of the design considerations involved in this process and an insight to the future direction of the technology.

Transcatheter aortic valve implantation using anatomically oriented, marrow stromal cell-based, stented, tissue-engineered heart valves: technical considerations and implications for translational cell-based heart valve concepts

OBJECTIVES

While transcatheter aortic valve implantation (TAVI) has rapidly evolved for the treatment of aortic valve disease, the currently used bioprostheses are prone to continuous calcific degeneration. Thus, autologous, cell-based, living, tissue-engineered heart valves (TEHVs) with regeneration potential have been suggested to overcome these limitations. We investigate the technical feasibility of combining the concept of TEHV with transapical implantation technology using a state-of-the-art transcatheter delivery system facilitating the exact anatomical position in the systemic circulation.

METHODS

Trileaflet TEHVs fabricated from biodegradable synthetic scaffolds were sewn onto self-expanding Nitinol stents seeded with autologous marrow stromal cells, crimped and transapically delivered into the orthotopic aortic valve position of adult sheep (n = 4) using the JenaValve transapical TAVI System (JenaValve, Munich, Germany). Delivery, positioning and functionality were assessed by angiography and echocardiography before the TEHV underwent post-mortem gross examination. For three-dimensional reconstruction of the stent position of the anatomically oriented system, a computed tomography analysis was performed post-mortem.

RESULTS

Anatomically oriented, transapical delivery of marrow stromal cell-based TEHV into the orthotopic aortic valve position was successful in all animals (n = 4), with a duration from cell harvest to TEHV implantation of 101 ± 6 min. Fluoroscopy and echocardiography displayed sufficient positioning, thereby entirely excluding the native leaflets. There were no signs of coronary obstruction. All TEHV tolerated the loading pressure of the systemic circulation and no acute ruptures occurred. Animals displayed intact and mobile leaflets with an adequate functionality. The mean transvalvular gradient was 7.8 ± 0.9 mmHg, and the mean effective orifice area was 1.73 ± 0.02 cm(2). Paravalvular leakage was present in two animals, and central aortic regurgitation due to a single-leaflet prolapse was detected in two, which was primarily related to the leaflet design. No stent dislocation, migration or affection of the mitral valve was observed.

CONCLUSIONS

For the first time, we demonstrate the technical feasibility of a transapical TEHV delivery into the aortic valve position using a commercially available and clinically applied transapical implantation system that allows for exact anatomical positioning. Our data indicate that the combination of TEHV and a state-of-the-art transapical delivery system is feasible, representing an important step towards translational, transcatheter-based TEHV concepts.