Neosinus and Sinus Flow After Self-Expanding and Balloon-Expandable Transcatheter Aortic Valve Replacement

Hydrogel-polyurethane fiber composites with enhanced microarchitectural control for heart valve replacement

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single-phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde-fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D-printed hydrogel coating setup was developed to make valve composites for device-level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2 ) met ISO 5840-2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post-spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel-polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model-directed fabrication toward optimizing durability as a function of fiber microarchitecture.

Comparison of a novel self-expanding transcatheter heart valve with two established devices for treatment of degenerated surgical aortic bioprostheses

AIMS

This study was performed to compare haemodynamic properties of a novel transcatheter heart valve (THV) with two established valve technologies for treatment of failing surgical aortic bioprosthetic valves (SAV). The ALLEGRA THV has been recently described with a proven safety and performance profile.

METHODS AND RESULTS

The study was designed as a retrospective, single-centre study investigating 112 patients (77.7 ± 7.1 years, 53.8% female, STS score 6.8 ± 5.8% and logEuroSCORE I 27.4 ± 16.1%) with failing SAV. Patients were treated with the ALLEGRA THV (NVT, n = 24), the CoreValve/EvolutR (MTD, n = 64) or the Edwards Sapien/Sapien XT/Sapien 3 (EDW, n = 24). Adverse events, haemodynamic outcomes and patient safety were analysed according to VARC-3 definitions. Overall procedural success was high (94.6%), even though 58.9% of the treated SAV were classified as small (true inner diameter < 21 mm). After treatment, the mean pressure gradient was significantly reduced (baseline: 33.7 ± 16.5 mmHg, discharge: 18.0 ± 7.1 mmHg), with a corresponding increase in effective orifice area (EOA). The complication rates did not differ in between groups. There was a trend to lower mean transvalvular gradients after implantation of self-expanding THV with supra-annular valve function, despite a higher frequency of smaller SAVs in the NVT and MTD group. Additionally, comparison between NVT and MTD revealed statistically lower transvalvular gradients (NVT 14.9 ± 5.0 mmHg, MTD 18.7 ± 7.5 mmHg, p = 0.0295) in a subgroup analysis.

CONCLUSIONS

Valve-in-valve (ViV) treatment of failing SAV with supra-annular design like the ALLEGRA THV resulted in favourable haemodynamic outcomes with similar low clinical event rates and may therefore be an interesting alternative for VIV TAVI.

Coronary Perfusion After Valve-in-Valve Transcatheter Aortic Valve Implantation in Small Aortic Root: In Vitro Experimental Assessment

Coronary flow obstruction following transcatheter aortic valve-in-valve implantation (VIV-TAVI) is associated with a high mortality risk. The aim of this work was to quantify the coronary perfusion after VIV-TAVI in a high-risk aortic root anatomy. 3D printed models of small aortic root were used to simulate the implantation of a TAVI prosthesis (Portico 23) into surgical prostheses (Trifecta 19 and 21). The aortic root models were tested in a pulsatile in vitro bench setup with a coronary perfusion simulator. The tests were performed at baseline and post-VIV-TAVI procedure in aligned and misaligned commissural configurations under simulated hemodynamic rest and exercise conditions. The experimental design provided highly controllable and repeatable flow and pressure conditions. The left and right coronary mean flow did not differ significantly at pre- and post-VIV-TAVI procedure in any tested configurations. The commissural misalignment did not induce any significant alterations to the coronary flow. High-risk aortic root anatomy did not trigger coronary ostia obstruction or coronary flow alteration after transcatheter aortic valve implantation in a surgical bioprosthesis as shown from in-vitro flow loop tests.

Subclinical Leaflet Thrombosis After Balloon versus Self-Expandable Transcatheter Aortic Valve Implantation

Hypoattenuated leaflet thickening (HALT) has been recognized as one of the complications after transcatheter aortic valve implantation and may promote structural valve degeneration and increase the risk of cerebrovascular events. The 2 main types of available transcatheter heart valves (THVs), the balloon-expandable (BE) and the self-expanding (SE), are interchangeably used in clinical practice despite substantial design differences. There is unclear evidence on whether these 2 different THV models are achieving similar or different rates of subclinical leaflet thrombosis/HALT. A systematic search of electronic databases was conducted to identify studies that reported the incidence of HALT between SE THVs and BE THVs. The Mantel-Haenszel method was used to calculate the 95% confidence interval and pooled risk ratio with a random-effects model. A total of 126 records were identified, of which 22 studies comprising 14,401 patients were included in our final analysis. Among 5,951 patients receiving SE THVs, 194 (3.2%) developed HALT, compared with 8,450 patients receiving BE THVs, of whom 484 (5.7%) developed HALT. There was a statistically significant decrease in the risk of developing HALT in patients receiving SE THVs compared with those receiving BE THVs (risk ratio 0.75, 95% confidence interval 0.59 to 0.95, I² 32%, p = 0.02). In conclusion, could potentially reduce the risk of HALT/subclinical leaflet thrombosis.

Long-term prognostic impact of paravalvular leakage on coronary artery disease requires patient-specific quantification of hemodynamics

Transcatheter aortic valve replacement (TAVR) is a frequently used minimally invasive intervention for patient with aortic stenosis across a broad risk spectrum. While coronary artery disease (CAD) is present in approximately half of TAVR candidates, correlation of post-TAVR complications such as paravalvular leakage (PVL) or misalignment with CAD are not fully understood. For this purpose, we developed a multiscale computational framework based on a patient-specific lumped-parameter algorithm and a 3-D strongly-coupled fluid-structure interaction model to quantify metrics of global circulatory function, metrics of global cardiac function and local cardiac fluid dynamics in 6 patients. Based on our findings, PVL limits the benefits of TAVR and restricts coronary perfusion due to the lack of sufficient coronary blood flow during diastole phase (e.g., maximum coronary flow rate reduced by 21.73%, 21.43% and 21.43% in the left anterior descending (LAD), left circumflex (LCX) and right coronary artery (RCA) respectively (N = 6)). Moreover, PVL may increase the LV load (e.g., LV load increased by 17.57% (N = 6)) and decrease the coronary wall shear stress (e.g., maximum wall shear stress reduced by 20.62%, 21.92%, 22.28% and 25.66% in the left main coronary artery (LMCA), left anterior descending (LAD), left circumflex (LCX) and right coronary artery (RCA) respectively (N = 6)), which could promote atherosclerosis development through loss of the physiological flow-oriented alignment of endothelial cells. This study demonstrated that a rigorously developed personalized image-based computational framework can provide vital insights into underlying mechanics of TAVR and CAD interactions and assist in treatment planning and patient risk stratification in patients.

Transcatheter aortic valve implantation with Allegra: procedural and mid-term outcomes according to experience phase in a high-volume center

BACKGROUND

Transcatheter aortic valve implantation (TAVI) has revolutionized the management of aortic stenosis. We aimed at appraising effectiveness of a new self-expandable TAVI device.

METHODS

We retrospectively analyzed our institutional experience with Allegra (Biosensors, Morges, Switzerland) for TAVI, focusing on procedural outcomes and 1-month adverse events. We explored the impact of operator experience with this device, dividing patients according to their time of intervention.

RESULTS

Between 2018 and 2021, a total of 50 patients underwent TAVI with Allegra, with average age of 81 years, 80% women, and 50% at low or intermediate surgical risk. No major significant difference in baseline patient features were found when comparing Phase 1 and Phase 2, except for baseline left ventricular ejection fraction and New York Heart Association, which were worse in Phase 1. All procedures were performed transfemorally and percutaneously, with predilation in 94% and postdilation in 36%, yielding device success in 98%, and procedural success in 96%. No significant differences in procedural features were found when comparing Phase 1 vs. Phase 2 (all P>0.05). One-month follow-up was also favorable, with no significant difference in adverse outcomes according to phase, and a total of 1 (4%) death, 1 (4%) myocardial infarction, 1 (4%) minor vascular complication, and 4 (8%) permanent pacemaker implantations. Consistent findings were obtained at exploratory 6-month follow-up.

CONCLUSIONS

The Allegra TAVI device is associated with favorable short-to-midterm outcomes in experienced hands. Operators already proficient with other devices can achieve satisfactory results even in the early phase of adoption of Allegra.

The search for optimal antithrombotic therapy in transcatheter aortic valve implantation: facts and uncertainties

Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure, which is used frequently in patients with symptomatic severe aortic valve stenosis. Most patients undergoing TAVI are over 80 years of age with a high bleeding as well as thrombotic risk. Despite the increasing safety of the procedure, thromboembolic events [stroke, (subclinical) valve thrombosis] remain prevalent. As a consequence, antithrombotic prophylaxis is routinely used and only recently new data on the efficacy and safety of antithrombotic drugs has become available. On the other hand, these antithrombotic drugs increase bleeding in a population with unique aortic stenosis-related bleeding characteristics (such as acquired von Willebrand factor defect and angiodysplasia). In this review, we discuss the impact of thromboembolic and bleeding events, the current optimal antithrombotic therapy based on registries and recent randomized controlled trials, as well as try to give a practical guide how to treat these high-risk patients. Finally, we discuss knowledge gaps and future research needed to fill these gaps.

Stroke prevention during and after transcatheter aortic valve implantation: From cerebral protection devices to antithrombotic management

Since its conception, transcatheter aortic valve implantation (TAVI) has undergone important improvements both in the implantation technique and in transcatheter devices, allowing an enthusiastic adoption of this therapeutic approach in a wide population of patients previously without a surgical option and managed conservatively. Nowadays, patients with severe symptomatic aortic stenosis are typically managed with TAVI, regardless of their risk to surgery, improving the prognosis of patients and thus achieving an exponential global expansion of its use. However, thromboembolic and hemorrhagic complications remain a latent concern in TAVI recipients. Both complications can appear simultaneously in the periprocedural period or during the follow-up, and when minor, they resolved without apparent sequelae, but in a relevant percentage of cases, they are devastating, overshadowing the benefit achieved with TAVI. Our review outlines the etiology and incidence of thromboembolic complications associated with TAVI, the main current strategies for their prevention, and the implications of its pharmacological management at the follow-up in a TAVI population, mostly frail and predisposed to bleeding complications.

Expanding our horizons for the use of transcatheter self-expanding valves: what does the future hold?

INTRODUCTION

Transcatheter aortic valve implantation (TAVI) is an established alternative to aortic valve surgery in patient with severe aortic valve stenosis. As interventionalists are pushing towards treatment of patients with lower risk profile with a wide range of anatomies, contemporary transcatheter heart valves (THV) should offer an excellent performance in terms of residual gradient, rate of pacemaker and perivalvular leak.

AREAS COVERED

Self-expandable (SE) valve offer a valid alternative to balloon-expandable (BE) valves, nevertheless comparative trials suggest a better outcome of patients treated with BE over SE platforms. New generation SE valves offer an excellent outcome in terms of procedural safety, however implementations in valve design and performance are required to reach the BE valves performance.

EXPERT COMMENTARY

in the near future, new devices should be able to obtain optimal results with a negligible rate of complications. Developments in the design of the delivery system together with refinements in valve technology are desirable to achieve results which are comparable to surgical aortic valve replacement.