Can mechanical heart valves perform similarly to tissue valves? An in vitro study.

Current surgical aortic valve (AV) replacement options include bioprosthetic and mechanical heart valves (MHVs), each with inherent limitations. Bioprosthetic valves offer superior hemodynamics but suffer from durability issues, typically initiating deterioration within 7-8 years. MHVs, while durable, necessitate lifelong anticoagulation therapy, presenting risks such as severe bleeding and thromboembolic events. The need for anticoagulants is caused by non-physiological flow through the hinge area during the closed phase and large spikes of regional backflow velocity (RBV) during the closing phase that produces high shear events. This study introduces the iValve, a novel MHV designed to combine the hemodynamic benefits of bioprosthetic valves with the durability of MHVs without requiring anticoagulation. The iValve features eye-like leaflets, a saddle-shaped housing, and an optimized hinge design to enhance blood flow and minimize thrombotic risk. Fabricated using 6061-T6 aluminum and polyether ether ketone (PEEK), twelve iValve iterations were evaluated for their opening and closing dynamics. The reported top-performing prototypes demonstrated competitive performance against industry standards. The proposed iValve prototype exhibited a mean RBV of -4.34 m/s with no spikes in RBV, performing similarly to bioprosthetic valves and significantly outperforming existing MHVs. The iValve's optimized design showed a 7-10% reduction in closing time and a substantial decrease in RBV spikes, potentially reducing the need for anticoagulation therapy. This study highlights the iValve's potential to revolutionize prosthetic heart valve technology by offering a durable, hemodynamically superior solution that mitigates the drawbacks of current MHVs.

Tissue versus mechanical mitral valve replacement in patients aged 50-70: a propensity-matched analysis.

OBJECTIVES: There remains debate over the optimal mitral valve replacement (MVR) option for patients aged 50-70 years. The objective of this study was to retrospectively compare the long-term outcomes of mechanical and bioprosthetic MVR in this patient population. METHODS: Data from patients undergoing MVR between 2004 and 2018 were retrospectively reviewed. The primary outcome was all-cause mortality. Secondary outcomes included perioperative and late morbidity. RESULTS: Two hundred and eight-six propensity-matched patients (n = 143 mechanical; n = 143 bioprosthetic) aged 50-70 years were included in the final analysis. Maximum follow-up was 15.8 years. There was no significant difference in all-cause mortality between the groups at 30 days, 1 year, 5 years, 10 years, and at the longest follow-up. Patients who underwent mechanical MVR experienced significantly lower rates of postoperative atrial fibrillation (P = 0.001). There were no significant differences in rates of sepsis, acute kidney injury, superficial and deep sternal wound infection, mediastinal bleeding, and permanent pacemaker implantation. At the longest follow-up, there were no differences in myocardial infarction, stroke, heart failure or overall rehospitalization. At the same time point, there was an increased rate of MVR in patients receiving a bioprosthetic valve (P = 0.015). CONCLUSIONS: Survival following mechanical and bioprosthetic MVR in patients 50-70 years of age is similar to up to 15 years of follow-up. Bioprosthetic MVR is associated with an increased risk of repeat MVR. Mechanical MVR is not associated with an increased risk of stroke. Valve selection in this patient population requires diligent consideration of structural valve deterioration and subsequent reoperation risk as well as bleeding and thromboembolic risk.

Facile engineering of interactive double network hydrogels for heart valve regeneration.

Regenerative heart valve prostheses are essential for treating valvular heart disease, which requested interactive materials that can adapt to the tissue remodeling process. Such materials typically involves intricate designs with multiple active components, limiting their translational potential. This study introduces a facile method to engineer interactive materials for heart valve regeneration using 1,1'-thiocarbonyldiimidazole (TCDI) chemistry. TCDI crosslinking forms cleavable thiourea and thiocarbamate linkages which could gradually release H2S during degradation, therefore regulates the immune microenvironment and accelerates tissue remodeling. By employing this approach, a double network hydrogel was formed on decellularized heart valves (DHVs), showcasing robust anti-calcification and anti-thrombosis properties post fatigue testing. Post-implantation, the DHVs could adaptively degrade during recellularization, releasing H2S to further support tissue regeneration. Therefore, the comprehensive endothelial cell coverage and notable extracellular matrix remodeling could be clearly observed. This accessible and integrated strategy effectively overcomes various limitations of bioprosthetic valves, showing promise as an attractive approach for immune modulation of biomaterials.

Evolut transcatheter aortic valve replacement explant and aortic root repair with an annular patch in the setting of endocarditis.

As a consequence of the growing number of implanted transcatheter aortic valve prostheses, the increasing incidence of early and late complications of biological valves requires in several cases surgical explantation of the transcatheter valve and subsequent aortic root or surgical aortic valve replacement. In this video tutorial, we show how to avoid aortic root damage in the surgical explantation of a transcatheter aortic valve bioprosthesis in a patient with a dysfunctional transcatheter aortic valve prosthesis affected by endocarditis 15 months after implantation. The infected prosthesis and all foreign materials, concomitant to the calcified native valve, were excised en bloc in preparation for the extensive debridement of infected tissue in the abscess cavity. The defect on the aortic annulus was reconstructed using a pericardial patch, followed by a surgical valve implant.

Robotic totally endoscopic aortic valve replacement with a sutured bioprosthesis.

Surgical robots have been utilized to facilitate a truly minimally invasive approach in cardiac surgery. Robotic aortic valve replacement allows for a totally endoscopic approach with better visualization in a wider range of patients with varying anatomies. It has the potential advantages of faster functional recovery and superior cosmetic outcomes compared to traditional sternotomy or thoracotomy approaches. In this case report, we show the details of robotic totally endoscopic aortic valve replacement.

Decellularized aortic homografts versus mechanical composite grafts for aortic root replacement.

OBJECTIVES: Mechanical composite valve grafts (MCVGs) are the first-line therapy for aortic root replacement in young adults. Decellularized aortic homografts (DAH) present a promising novel alternative due to their lower thrombogenicity. We aimed to compare both treatment options regarding survival and valve-related adverse events. METHODS: This study was designed as a single-centre retrospective cohort study including patients who underwent root replacement with MCVG or DAH between 2000 and 2022. Urgent or emergent procedures were excluded. RESULTS: The study cohort included 289 patients (MCVG n = 216, DAH n = 73) with a mean age of 48.5 ± 12 years (MCVG 49 ± 12 years vs DAH 47 ± 11 years; P = 0.23) and a median EuroScore II of 1.7% (1.2, 2.6). The 30-day mortality was 1% (n = 3). Cumulative survival at 3 years was 99% for DAH and 94% for MCVG, respectively (P = 0.15). Mean follow-up was 98.9 ± 72.7 months. Bleeding events (n = 14, 6.5%) and thromboembolism (n = 14, 6.5%) were only observed in the MCVG group (P = 0.19 and 0.09, respectively). Four cases (5%) of moderate structural valve deterioration occurred, all in the DAH group (P ≤ 0.001). The cumulative incidence of a composite end point of valve-related adverse events was significantly higher in the MCVG group (P = 0.0295). CONCLUSIONS: Aortic root replacement with MCVGs and decellularized aortic homografts showed low mortality in an elective setting. Patients in the homograft cohort demonstrated significantly higher freedom from valve-related adverse events. DAH present a promising treatment option for young patients requiring root replacement; however, data on long-term durability are needed.

Computational Study on the Effects of Valve Orientation on the Hemodynamics and Leaflet Dynamics of Bioprosthetic Pulmonary Valves.

Pulmonary valves do not display a fibrous annulus as do other valves in the heart; thus, pulmonary valves can be implanted at multiple orientations and locations within the right ventricular outflow tract (RVOT). This gives surgeons more freedom when implanting the valve but it also results in uncertainties regarding placement, particularly with respect to valve orientation. We investigate the pulmonary artery hemodynamics and valve leaflet dynamics of pulmonary valve replacements (PVRs) with various orientations via fluid-structure interaction (FSI) models. A canonical model of the branching pulmonary artery is coupled with a dynamic model of a pulmonary valve, and from this we quantify the effect of valve implant orientation on the postvalvular hemodynamics and leaflet dynamics. Metrics such as turbulent kinetic energy (TKE), branch pulmonary artery flow distributions, projected valve opening area (PVOA), and pressure differentials across the valve leaflets are analyzed. Our results indicate that off-axis orientation results in higher pressure forces and flow and energy asymmetry, which potentially have implications for long-term durability of implanted bioprosthetic valves.

Sustained Intraprocedural Cardiac Arrest During BASILICA TAVR.

The bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) procedure allows patients with severe aortic stenosis and anatomical challenges from aortic leaflet orientation, positioning of coronary ostia, and height of sinuses of Valsalva to undergo TAVR. We present a case of intraprocedural cardiac arrest secondary to iatrogenic left main coronary artery obstruction following a successful BASILICA procedure.

Three-dimensional printing for complex cardiac reoperations: optimising Gerbode defect repairs.

Cardiac fistulas present diagnostical and therapeutical challenges due to their variability in size, shape and pathway. Three-dimensional printing is increasingly used to provide a tactile representation that aids in preoperative planning and patient education. We present the case of a female in her 60s who developed a fistula between the left ventricle, right atrium and coronary sinus 2 years after bioprosthetic valve replacement. We used three-dimensional modelling to better understand her cardiac anatomy and optimise our surgical approach. She was discharged home without deficit following an uneventful postoperative course. Three-dimensional printing can improve patient care through tangible demonstration, preoperative planning and trainee education.

A novel balloon-expandable transcatheter aortic valve bioprosthesis: Myval and Myval Octacor.

INTRODUCTION: Over the past two decades, transcatheter aortic valve replacement (TAVR) has expanded its application across all surgical risk levels, including low-risk patients, where, due to longer life expectancy, reducing common pitfalls of TAVR is essential. To address these needs, many technological advancements have been developed. Myval and the new generation Myval Octacor (Meril Life Sciences Pvt. Ltd) are novel balloon-expandable (BE) transcatheter heart valve (THV) systems designed for the treatment of severe aortic stenosis. AREAS COVERED: This review aims to illustrate the design features of these novel THVs and the main evidence from available studies. Furthermore, we provide evidence of these THVs' performance in challenging scenarios such as extra-large aortic annuli, bicuspid aortic valves, and valve-in-valve/valve-in-ring procedures. EXPERT OPINION: Myval and Myval Octacor have demonstrated comparable early safety and clinical efficacy to the leading contemporary THVs, exhibiting remarkably low rates of moderate to severe paravalvular leak (PVL) and permanent pacemaker implantation (PPI). The wide range of sizes offered by the Myval family may minimize the risk of under-/oversizing, potentially explaining the lower rates of the aforementioned phenomena. Moreover, the presence of both internal skirt and external reinforced cuff may also explain the low rate of moderate to severe PVL.

Durability of transcatheter aortic valve implantation.

Transcatheter aortic valve implantation (TAVI) is now utilised as a less invasive alternative to surgical aortic valve replacement (SAVR) across the whole spectrum of surgical risk. Long-term durability of the bioprosthetic valves has become a key goal of TAVI as this procedure is now considered for younger and lower-risk populations. The purpose of this article is to present a state-of-the-art overview on the definition, aetiology, risk factors, mechanisms, diagnosis, clinical impact, and management of bioprosthetic valve dysfunction (BVD) and failure (BVF) following TAVI with a comparative perspective versus SAVR. Structural valve deterioration (SVD) is the main factor limiting the durability of the bioprosthetic valves used for TAVI or SAVR, but non-structural BVD, such as prosthesis-patient mismatch and paravalvular regurgitation, as well as valve thrombosis or endocarditis may also lead to BVF. The incidence of BVF related to SVD or other causes is low (<5%) at midterm (5- to 8-year) follow-up and compares favourably with that of SAVR. The long-term follow-up data of randomised trials conducted with the first generations of transcatheter heart valves also suggest similar valve durability in TAVI versus SAVR at 10 years, but these trials suffer from major survivorship bias, and the long-term durability of TAVI will need to be confirmed by the analysis of the low-risk TAVI versus SAVR trials at 10 years.

Bifocal coronary sinus pacing and transcatheter tricuspid valve-in-valve implantation: an innovative combined approach.

One of the most common complications of tricuspid valve replacement is atrioventricular block (AVB), often requiring permanent pacing. The endocardial pacemaker lead, placed in the right ventricle, may sometimes interfere with the implanted prosthesis, causing its early dysfunction and the need for alternative sites of pacing. To the best of our knowledge, we present the first case of a successful combined percutaneous procedure consisting of the implantation of two leads in the coronary sinus for univentricular bifocal pacing and a transcatheter tricuspid valve-in-valve implantation in a young patient with severe dysfunction of the tricuspid bioprosthesis, requiring permanent pacing for a postsurgical complete atrioventricular block.

Tricuspid valve replacement with surgery can often lead to cardiac rhythm disorders requiring a permanent pacemaker. This device may occasionally damage the tricuspid prosthesis. We present the first case of a combined procedure of tricuspid valve replacement and device implantation distant from the prosthesis without the need for a surgical approach in a young patient with severe tricuspid prosthesis malfunctioning and permanent pacing.

One-Year Outcomes of Transseptal Mitral Valve-in-Valve in Intermediate Surgical Risk Patients.

BACKGROUND: Transcatheter mitral valve-in-valve replacement offers a less-invasive alternative for high-risk patients with bioprosthetic valve failure. Limited experience exists in intermediate-risk patients. We aim to evaluate 1-year outcomes of the PARTNER 3 mitral valve-in-valve study. METHODS: This prospective, single-arm, multicenter study enrolled symptomatic patients with a failing mitral bioprosthesis demonstrating greater than or equal to moderate stenosis and regurgitation and Society of Thoracic Surgeons score ≥3% and <8%. A balloon-expandable transcatheter heart valve (SAPIEN 3, Edwards Lifesciences) was used via a transeptal approach. The primary end point was the composite of all-cause mortality and stroke at 1 year. RESULTS: A total of 50 patients from 12 sites underwent mitral valve-in-valve from 2018 to 2021. The mean age was 70.1±9.7 years, mean Society of Thoracic Surgeons score was 4.1%±1.6%, and 54% were female. There were no primary end point events (mortality or stroke) through 1 year, and no left-ventricular outflow tract obstruction, endocarditis, or mitral valve reintervention was reported. Six patients (12%) required rehospitalization, including heart failure (n=2), minor procedural side effects (n=2), and valve thrombosis (n=2; both resolved with anticoagulation). An additional valve thrombosis was associated with no significant clinical sequelae. From baseline to 1 year, all subjects with available data had none/trace or mild (grade 1+) mitral regurgitation and the New York Heart Association class improved in 87.2% (41/47) of patients. CONCLUSIONS: Mitral valve-in-valve with a balloon-expandable valve via transseptal approach in intermediate-risk patients was associated with improved symptoms and quality of life, adequate transcatheter valve performance, and no mortality or stroke at 1-year follow-up. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03193801.

Effect of bioprosthetic leaflet anisotropy on stent dynamics of Transcatheter Aortic Valve Replacement devices.

The assessment of stent fatigue in Transcatheter Aortic Valve Replacement (TAVR) systems is critical for the design of next-generation devices, both in vitro and in vivo. The mechanical properties of the bioprosthetic heart valves (BHVs) have a significant impact on the fatigue life of the metallic stent and thus must be taken into consideration when evaluating new TAVR device designs. This study aims to investigate the relationship between BHV anisotropic behaviour and the asymmetric deflections of the stent frame observed during in vitro testing. An explicit dynamics finite element model of the nitinol stent with attached bioprosthetic valve leaflets was developed to evaluate the deflections of the TAVR device under haemodynamic loading. Our results demonstrate that pericardium behaviour plays a dominant role in determining stent frame deflection. The anisotropic behaviour of the leaflets, resulting from collagen fibre orientation, affects the extent of deflection encountered by each commissure of the frame. This leads to asymmetric variation in frame deflection that can influence the overall fatigue life of the nitinol stent. This study highlights the importance of considering both the flexible nature of the metallic stent as well as the leaflet anisotropic behaviour in the design and fatigue assessment of TAVR systems.

Aortic valved homograft degeneration: surgical or transcatheter approach for repeat aortic valve replacement?

OBJECTIVES: Aortic valved allografts (homografts) have been used alternatively to mechanical or biological valve prostheses in expectation of better durability; however, homograft valves do degenerate, and redo procedures have proven challenging due to heavy wall calcification. The aim of the study was to compare the outcome of open surgical (SAVR) and transcatheter aortic valve replacement (TAVR) in degenerated homografts. METHODS: Between 1993 and 2022, 81 patients underwent repeat aortic valve procedures having previously received an aortic homograft. The redo had become necessary due to regurgitation in 85% and stenosis in 15%. Sixty-five percent underwent open surgery, 35% TAVR. RESULTS: Isolated SAVR was possible in 79%, and root procedures were necessary in 21%. TAVR was performed in 79% via transfemoral and 21% via transapical access. Median prosthetic valve size was 23 (22.3-23.2) mm in the SAVR and 26 (25.2-26.9) in the TAVR group. Thirty-day mortality was 0% in the TAVR and 7% in the SAVR group (P = n.s.). TAVR showed a significantly better outcome concerning prolonged ventilation (0 vs 21%, P = 0.013) as well as ICU (1 vs 2 days; P < 0.001) and in-hospital stay (10.5 vs 13 days; P = 0.028). Five-year survival was statistically comparable between groups, and no severe leakage was observed. CONCLUSIONS: SAVR following structural homograft degeneration shows acceptable results, but the perioperative risk remains substantial and poorly predictable. TAVR presents a reasonable and more easily accessible alternative and is associated with good short- and mid-term results. In the absence of relevant contraindications, TAVR is presently the preferred treatment option for these patients at our center.

Age-Based Outcomes After Surgical Aortic Valve Replacement With Bioprosthetic Versus Mechanical Valves.

Recommendations for prosthesis type in older patients who underwent surgical aortic valve replacement (SAVR) are established, albeit undervalidated. The purpose of this study is to compare outcomes after bioprosthetic versus mechanical SAVR across various age groups. This was a retrospective study using an institutional SAVR database. All patients who underwent isolated SAVR were compared across valve types and age strata (<65 years, 65 to 75 years, >75 years). Patients who underwent concomitant operations, aortic root interventions, or previous aortic valve replacement were excluded. Objective survival and aortic valve reinterventions were compared. Kaplan-Meier survival estimation and multivariate regression were performed. A total of 1,847 patients underwent SAVR from 2010 to 2023. A total of 1,452 patients (78.6%) received bioprosthetic valves, whereas 395 (21.4%) received mechanical valves. Of those who received bioprosthetic valves, 349 (24.0%) were aged <65 years, 627 (43.2%) were 65 to 75 years, and 476 (32.8%%) were older than 75 years. For patients who received mechanical valves, 308 (78.0%) were aged <65 years, 84 (21.3%) were between 65 and 75 years, and 3 (0.7%) were >75 years. The median follow-up in the total cohort was 6.2 (2.6 to 8.9) years. No statistically significant differences were observed in early-term Kaplan-Meier survival estimates between SAVR valve types in all age groups. However, the cumulative incidence estimates of aortic valve reintervention were significantly higher in patients aged under 65 years who received bioprosthetic than those who received mechanical valves, with 5-year reintervention rates of 5.8% and 3.1%, respectively (p = 0.002). On competing risk analysis for valve reintervention, bioprosthetic valves were significantly associated with an increased hazard of aortic valve reintervention (hazard ratio 3.35, 95% confidence interval 1.73 to 6.49, p <0.001). In conclusion, SAVR with bioprosthetic valves (particularly, in patients aged <65 years) was comparable in survival to mechanical valve SAVR but significantly associated with increased valve reintervention rates.