Long-Term Survival After Bovine Pericardial Versus Porcine Stented Bioprosthetic Aortic Valve Replacement: Does Valve Choice Matter?

Outcomes of bovine versus porcine surgical aortic valve replacement

INTRODUCTION

There are no guidelines regarding the use of bovine pericardial or porcine valves for aortic valve replacement, and prior studies have yielded conflicting results. The current study sought to compare short- and long-term outcomes in propensity-matched cohorts of patients undergoing isolated aortic valve replacement (AVR) with bovine versus porcine valves.

METHODS

This was a retrospective study utilizing an institutional database of all isolated bioprosthetic surgical aortic valve replacements performed at our center from 2010 to 2020. Patients were stratified according to type of bioprosthetic valve (bovine pericardial or porcine), and 1:1 propensity-score matching was applied. Kaplan-Meier survival estimation and multivariable Cox regression for mortality were performed. Cumulative incidence functions were generated for all-cause readmissions and aortic valve reinterventions.

RESULTS

A total of 1502 patients were identified, 1090 (72.6%) of whom received a bovine prosthesis and 412 (27.4%) of whom received a porcine prosthesis. Propensity-score matching resulted in 412 risk-adjusted pairs. There were no significant differences in clinical or echocardiographic postoperative outcomes in the matched cohorts. Kaplan-Meier survival estimates were comparable, and, on multivariable Cox regression, valve type was not significantly associated with long-term mortality (hazard ratio: 1.02, 95% confidence interval: 0.74, 1.40, p = .924). Additionally, there were no significant differences in competing-risk cumulative incidence estimates for all-cause readmissions (p = .68) or aortic valve reinterventions (p = .25) in the matched cohorts.

CONCLUSION

The use of either bovine or porcine bioprosthetic aortic valves yields comparable postoperative outcomes, long-term survival, freedom from reintervention, and freedom from readmission.

Review of bioprosthetic structural valve deterioration: Patient or valve?

BACKGROUND

With guidelines progressively recommending bioprosthetic aortic valves in younger patients, a greater emphasis is placed on structural valve deterioration (SVD) as an important clinical endpoint for both transcatheter and surgically implanted valves. However, SVD of bioprosthetic valves is a complex entity with varying definitions in the literature and a multifaceted pathogenesis.

AIM

This review first aims to establish the most updated definitions of SVD as per the literature. We then explore the patient- and valve-related factors that play the greatest roles in facilitating early SVD.

METHODS

A PubMed literature review was conducted to identify the relevant research in this field within the past two decades.

CONCLUSION

Increasing rates of obesity and metabolic syndrome pose a significant risk to the longevity of bioprosthetic valves. Additionally, externally mounted valves have proven to sacrifice durability for superior haemodynamics. Bioprosthetic SVD continues to be a multifactorial issue that will require various patient- and valve-related factors to be addressed.

Imaging, Treatment Options, Patient Selection, and Outcome Considerations for Patients With Bicuspid Aortic Valve Disease

Transcatheter aortic valve replacement has emerged as a safe and effective alternative to surgical aortic valve replacement for patients with severe symptomatic aortic stenosis across the spectrum of surgical risks based on a series of foundational randomized clinical trials. Of note, patients with bicuspid aortic valve (BAV) disease were excluded from all these pivotal randomized trials, leaving a significant knowledge gap because BAVs are commonly encountered in patients referred for aortic valve surgery or intervention. In this comprehensive review, we aim to provide heart teams with a detailed insight into how to approach patients with BAV disease, focusing on imaging and characterization of bicuspid valves, an overview of surgical approaches, and an understanding of the current data behind the role of transcatheter aortic valve replacement for patients with BAV disease.

Biofabrication of Sodium Alginate Hydrogel Scaffolds for Heart Valve Tissue Engineering

Every year, thousands of aortic valve replacements must take place due to valve diseases. Tissue-engineered heart valves represent promising valve substitutes with remodeling, regeneration, and growth capabilities. However, the accurate reproduction of the complex three-dimensional (3D) anatomy of the aortic valve remains a challenge for current biofabrication methods. We present a novel technique for rapid fabrication of native-like tricuspid aortic valve scaffolds made of an alginate-based hydrogel. Using this technique, a sodium alginate hydrogel formulation is injected into a mold produced using a custom-made sugar glass 3D printer. The mold is then dissolved using a custom-made dissolving module, revealing the aortic valve scaffold. To assess the reproducibility of the technique, three scaffolds were thoroughly compared. CT (computed tomography) scans showed that the scaffolds respect the complex native geometry with minimal variations. The scaffolds were then tested in a cardiac bioreactor specially designed to reproduce physiological flow and pressure (aortic and ventricular) conditions. The flow and pressure profiles were similar to the physiological ones for the three valve scaffolds, with small variabilities. These early results establish the functional repeatability of this new biofabrication method and suggest its application for rapid fabrication of ready-to-use cell-seeded sodium alginate scaffolds for heart valve tissue engineering.

Pericardial Versus Porcine Valves for Surgical Aortic Valve Replacement

Two prototypes of material to constitute surgical bioprosthetic aortic valve (AV) are bovine pericardium and porcine valves. Earlier studies have consistently shown superior hemodynamic profiles in bovine pericardial valves, however, it is not clear whether such superior hemodynamic profiles can be translated into improved clinical outcomes. In patients undergoing isolated bioprosthetic surgical aortic valve replacement (AVR) (636 patients between January 2000 and May 2016), the use of bovine pericardial valves was associated with superior hemodynamic profiles and improved late survival as compared with porcine valves. Freedom from adverse valve-related complication rates were not significantly different between the 2 groups.

Background and Objectives

There still are controversies on which type between bovine pericardial and porcine valves is superior in the setting of aortic valve replacement (AVR). This study aims to compare clinical outcomes of AVR using between pericardial or porcine valves.

Methods

The study involved consecutive 636 patients underwent isolated AVR using stented bioprosthetic valves between January 2000 and May 2016. Of these, pericardial and porcine valves were implanted in 410 (pericardial group) and 226 patients (porcine group), respectively. Clinical outcomes including survival, structural valve deterioration (SVD) and trans-valvular pressure gradient were compared between the groups. To adjust for potential selection bias, inverse probability treatment weighting (IPTW) was conducted.

Results

The mean follow-up duration was 60.1±50.2 months. There were no significant differences in the rates of early mortality (3.1% vs. 3.1%; p=0.81) and SVD (0.3%/patient-year [PY] vs. 0.5%/PY; p=0.33) between groups. After adjustment using IPTW, however, landmark mortality analyses showed a significantly lower late (>8 years) mortality risk in pericardial group over porcine group (hazard ratio [HR], 0.61; 95% confidence interval, [CI] 0.41–0.90; p=0.01) while the risks of SVD were not significantly difference between groups (HR, 0.45; 95% CI, 0.12–1.70; p=0.24). Mean pressure gradient across prosthetic AV was lower in the Pericardial group than the Porcine group at both immediate postoperative point and latest follow-up (p values <0.001).

Conclusions

In patients undergoing bioprosthetic surgical AVR, bovine pericardial valves showed superior results in terms of postoperative hemodynamic profiles and late survival rates over porcine valves.

Surgical pericardial heart valves: 50 Years of evolution

Valve disease carries a huge burden globally and the number of heart valve procedures are projected to increase from the current 300 000 to 800 000 annually by 2050. Since its genesis 50 years ago, pericardial heart valve has moved leaps and bounds to ever more ingenious designs and manufacturing methods with parallel developments in cardiology and cardiovascular surgical treatments. This feat has only been possible through close collaboration of many scientific disciplines in the fields of engineering, material sciences, basic tissue biology, medicine and surgery. As the pace of change continues to accelerate, we ask the readers to go back with us in time to understand developments in design and function of pericardial heart valves. This descriptive review seeks to focus on the qualities of pericardial heart valves, the advantages, successes and failures encapsulating the evolution of surgically implanted pericardial heart valves over the past five decades. We present the data on comparison of the pericardial heart valves to porcine valves, discuss structural valve deterioration and the future of heart valve treatments.

Comparison of porcine versus bovine pericardial bioprosthesis in the mitral position

BACKGROUND

There are no reports of midterm outcomes after mitral valve replacement with a 25-mm bioprosthesis in a large series of patients. This study aimed to examine perioperative and midterm outcomes of bioprosthetic valve choice, porcine or bovine pericardial, in the mitral position, focusing on 25-mm valves.

METHODS

From 2007 to 2018, 467 patients received a mitral bioprosthesis, with or without concomitant procedures. Of these, 111 (23.8%) were porcine, and 356 (76.2%) were bovine pericardial, and 219 patients (46.9%) received a 25-mm valve. A propensity-matched cohort of 192 patients was used for outcome analyses. The influence of the valve type on midterm survival and incidence of cardiac death was assessed. Similarly, subanalysis stratified by valve size was conducted.

RESULTS

In matched patients, there were no differences in midterm survival and incidence of cardiac death between the two groups (log-rank test; p = .268 and p = .097, respectively). There were no differences in midterm survival and incidence of cardiac death between the 25-mm valve and larger valve (log-rank test; p = .563 and p = .597, respectively). The Cox proportional-hazards model revealed that the valve type and 25-mm valve did not affect midterm survival (p = .487 and p = .375, respectively) and incidence of cardiac death (p = .678 and p = .562, respectively).

CONCLUSIONS

The choice of a porcine or bovine pericardial bioprosthesis does not affect midterm survival and cardiac death. The 25-mm valves, whether bovine or porcine, could be an appropriate alternative when the patient's body size is small.

Porcine and bovine aortic valve comparison for surgical optimization: A fluid-structure interaction modeling study

BACKGROUND

Porcine aortic valve (PAV) and bovine aortic valve (BAV) are commonly used in aortic valve replacement (AVR) surgeries. A detailed comparison for their hemodynamic and structural stress/strain performances would help to better understand valve cardiac function and select valve type and size for AVR outcome optimizations.

METHODS

Eight fluid-structure interaction models were constructed to compare hemodynamic and stress/strain behaviors of PAV and BAV with 4 sizes (19, 21, 23, and 25 mm). Blood flow velocity, systolic cross-valve pressure gradient (SCVPG), geometric orifice area (GOA), flow shear stresses (FSS), and stress/strain were obtained for comparison.

RESULTS

Compared with PAV, BAV has better hemodynamic performance, with lower maximum flow velocity (7.17%) and pressure (9.82%), smaller pressure gradient (mean and peak SCVPG: 8.92% and 9.28%), larger GOA (9.56%) and lower FSS (6.61%). The averages of the mean and peak net pressure gradient values from 4 BAV models were 8.10% and 8.35% lower than that from PAV models. Larger valve sizes for both PAV and BAV had improved hemodynamic performance. Maximum flow velocity, pressure, mean SCVPG and maximum FSS from 25 mm BAV were 36.80%, 15.81%, 39.05% and 38.83% lower than those from 19 mm BAV. The GOA of PAV and BAV 25 mm Valve were 43.75% and 33.07% larger than 19 mm valves, respectively. BAV has lower stress on the leaflets than PAV.

CONCLUSIONS

BAV had better hemodynamic performance and lower leaflets stress than PAV. More patient studies are needed to validate our findings.

Durability of Mitral Valve Bioprostheses: A Meta-Analysis of Long-Term Follow-up Studies

BACKGROUND

Porcine and pericardial valves exhibited similar freedom from structural valve deterioration after aortic valve replacement. Limited data exist regarding their durability at long-term follow-up in the mitral position.

METHODS

A literature search was performed through online databases. Papers reporting freedom from tissue valve deterioration after mitral valve replacement with a follow-up longer than 5 years were retrieved. Four porcine valves (Carpentier-Edwards [Edwards Lifesciences, Irvine, CA] and Hancock, Hancock II, and Mosaic [Medtronic, Inc, Minneapolis, MN]) and 1 pericardial prosthesis (Carpentier-Edwards) were the objects of the study. The structural valve deterioration (SVD) rate per year was calculated for each type of prosthesis. Kaplan-Meier curves and log-rank test analysis were performed to compare the long-term durability of porcine and pericardial valves.

RESULTS

Forty full-text papers including more than 15,000 patients were considered for the meta-analysis. Porcine valves were generally implanted in younger patients in the first period after their introduction. The mean age of the patients receiving a mitral bioprosthesis increased from 50 to 70 years over the decades. In patients operated after 1980 who had similar mean age at the time of implant, freedom from SVD was higher in the group of porcine valves with Mosaic prosthesis, showing the lowest rate of SVD. Long-term survival was higher for Mosaic porcine and Carpentier pericardial valves.

CONCLUSIONS

In surgical populations that underwent mitral valve replacement after 1980 with new generation tissue valves and similar mean age at the implant time, we found, at long-term follow-up, a higher freedom from SVD in the group of porcine prostheses.

The Additional Value of Three-Dimensional Transesophageal Echocardiography in the Diagnosis of Unusual Complication of Bioprosthetic Mitral Valve

Primary tissue failure of bioprosthetic mitral valves due to cusp perforations or ruptures is an unusual complication on short-term follow-up. An 88-year-old male with a known history of mitral regurgitation (MR) treated with bioprosthetic valve replacement in 2016 was referred to our center for recurrent heart failure. The two-dimensional (2D) transthoracic echocardiography documented an intraprosthetic jet of regurgitation without identifying a clear morphological mechanism, nor quantifying precisely the mitral insufficiency. 3D transesophageal echocardiography (TOE) with the tool FlexiSlice added relevant information by providing insights into the pathophysiological mechanisms of MR. The present case emphasizes the importance of 3D TOE as a fundamental tool for the diagnostic algorithm of bioprosthetic valves failure, even in the more demanding cases.

Hemodynamics and reverse remodeling associated with Mosaic, Perimount and Trifecta aortic bioprostheses

Introduction: The implantation rate of aortic bioprostheses is increasing. Their durability has improved to some extent over the years and they allow for future transcatheter valve-in-valve deployment. In the lack of long term follow up, their hemodynamic profile, i.e. transvalvular mean pressure gradient and effective orifice area indexed, and the associated left ventricular reverse remodeling indexed are useful surrogates for clinical outcomes. Areas covered: A systematic review of the literature was conducted by searching Medline, Cochrane, Scielo, Embase databases, and grey literature until July 2018 for articles that perform comparisons among the three most popular aortic bioprostheses. Six randomized and 12 non-randomized studies were included with 565 patients receiving a Mosaic, 1334 a Perimount and 557 a Trifecta valve. These articles are heterogeneous but they allow the meta-analytic comparison of the abovementioned outcomes. Expert opinion: Compared to the Perimount valve, the Mosaic is hemodynamically inferior, while the Trifecta is superior. Despite these statistically significant differences, the left ventricular mass regression indexed, that is indicative of reverse remodeling, was comparable in all groups. All patients were similarly benefited. The predilection among these valves is fueled by their hemodynamic profile but not supported by the comparable reverse remodeling.

A comparison of early redo surgery rates in Mosaic porcine and Perimount bovine pericardial valves

OBJECTIVES

The objective of this study was to compare rates of redo surgery for the Medtronic Mosaic 305 A Porcine Prosthesis and the Carpentier-Edwards Perimount Pericardial Aortic Bioprosthesis 2900.

METHODS

This was a single-centre retrospective observational study. We included all 1018 patients who underwent aortic valve replacement with a Mosaic (n = 216) or Perimount (n = 809) bioprosthesis between October 2000 and August 2008. The total follow-up was 1508 patient-years for the Mosaic valve and 5813 for the Perimount valve. The maximal follow-up and interquartile range were 14.8 and 7.0 years for the Mosaic valve and 15.1 and 5.6 years for the Perimount valve, respectively. A propensity score-weighted version of the Cox model, Kaplan-Meier analysis and multivariate regression model was used.

RESULTS

Despite no statistical difference in the number of non-structural valve deterioration cases between valves, redo surgery occurred earlier in 10 (4.6%) Mosaic than for 17 (2.1%) Perimount valves (P = 0.02) and was required for structural valve deterioration in 5 (2.3%) Mosaic valves when compared with 7 (0.9%; P = 0.04) Perimount valves. Four of 5 Mosaic failures occurred before 5 years, whereas all Perimount failures occurred after 5 years. Redo surgery for non-structural valve deterioration occurred in 3 patients with Mosaic valves (1.4%) and no patients with Perimount valves. Surgery for the remaining patients with Perimount valves was due to infection or aortic disease.

CONCLUSIONS

Early redo surgery for structural valve degeneration was uncommon but occurred earlier for the Mosaic porcine than the Perimount bovine pericardial replacement aortic valve.

Mechanical behavior of bovine pericardium treated with hyaluronic acid derivative for bioprosthetic aortic valves

We studied the mechanical behavior of bovine pericardium (BP) after anticalcification treatment using hyaluronic acid (HA) derivative. To simulate the physiological environment and stimulate the calcification process, the BP samples were immersed into simulated body fluid solution. We conducted scanning electron microscopy with energy dispersive X-ray spectrometry, and uniaxial mechanical tests of HA-treated and non-treated samples. Although our microstructural analyses indicated that the HA treatment actually prevents the formation of calcium phosphate deposits, the mechanical tests show significant increase of stiffness of the HA-treated samples. Using data from our mechanical tests as input parameters, we performed finite element (FE) computer simulations to estimate how this increase in the BP stiffness affects the stress distribution in the bioprosthetic leaflet. Although the maximum stress observed during the closing phase of the membrane in vivo is below the experimental yield stress in all cases we analyzed, our FE results indicate that increase of BP stiffness due to HA anticalcification treatment results in higher risk of disruption and failure of the leaflets in bioprosthetic heart valves. Since our FE results indicate that the commissure and the fixed edge are the regions that withstand the highest mechanical stresses during the closing phase, new designs of the valve might be efficient to enhance the endurance of the prosthesis. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2273-2280, 2019.

Geometric Ring Annuloplasty for Aortic Valve Repair During Aortic Aneurysm Surgery: Two-Year Clinical Trial Results

OBJECTIVE

An aortic annuloplasty ring could be useful for aortic valve repair. This trial evaluated intermediate-term outcomes of internal geometric ring annuloplasty for repair of trileaflet and bicuspid aortic insufficiency associated with ascending aortic and/or aortic root aneurysms.

METHODS

Under regulatory supervision, 47 patients with aortic insufficiency and ascending aortic (n = 22) and/or aortic root (n = 25) aneurysms were managed with aortic valve repair and aneurysm resection. Valve repair was performed using trileaflet (n = 40) or bicuspid (n = 7) internal geometric rings, together with leaflet reconstruction. Ascending aortic and/or remodeling root replacements were accomplished with Dacron grafts 5 to 7 mm larger than the rings. An Echo Core Lab provided independent echocardiographic assessments, and changes over time were evaluated by Friedman tests.

RESULTS

Mean ± SD age was 60 ± 14 years, 57% (27/47) were male, 15% (7/47) had bicuspid valves, 87% (41/47) had moderate-to-severe aortic insufficiency, and 13% (6/47) had mild aortic insufficiency. All patients had annular dilatation, with a mean ± SD of 26.5 ± 2.6 mm before repair, and mean ± SD ring sizes were 21.7 ± 1.7 mm. Follow-up was 42 months (mean = 27 months). No operative mortality or valve-related complications occurred. Two patients died beyond 1 year from nonvalve-related causes. One patient required valve replacement for repair failure. Survival free of complications or valve replacement was 94% at 2 years. Significant reduction in aortic insufficiency and New York Heart Association class were observed (P < 0.0001), and valve gradients remained low. No heart block or direct ring complications occurred.

CONCLUSIONS

In preliminary regulatory studies, aortic ring annuloplasty seemed safe and effective during aortic aneurysm surgery. This approach could help standardize aortic valve repair.

Calcification and Oxidative Modifications Are Associated With Progressive Bioprosthetic Heart Valve Dysfunction

Background

Bioprosthetic heart valves (BHVs), fabricated from glutaraldehyde‐pretreated bovine pericardium or porcine aortic valves, are widely used for the surgical or interventional treatment of heart valve disease. Reoperation becomes increasingly necessary over time because of BHV dysfunction.

Methods and Results

Forty‐seven explanted BHV aortic valve replacements were retrieved at reoperation for clinically severe BHV dysfunction over the period 2010–2016. Clinical explant analyses of BHV leaflets for calcium (atomic absorption spectroscopy) and oxidized amino acids, per mass spectroscopy, were primary end points. Comorbidities for earlier BHV explant included diabetes mellitus and coronary artery bypass grafting. Mean calcium levels in BHV leaflets were significantly increased compared with unimplanted BHV (P<0.001); however, time to reoperation did not differ comparing calcified and noncalcified BHV. BHV dityrosine, an oxidized amino acid cross‐link, was significantly increased in the explants (227.55±33.27 μmol/mol [dityrosine/tyrosine]) but was undetectable in unimplanted leaflets (P<0.001). BHV regional analyses revealed that dityrosine, ranging from 57.5 to 227.8 μmol/mol (dityrosine/tyrosine), was detectable only in the midleaflet samples, indicating the site‐specific nature of dityrosine formation. 3‐Chlorotyrosine, an oxidized amino acid formed by myeloperoxidase‐catalyzed chlorinating oxidants, correlated with BHV calcium content in leaflet explant analyses from coronary artery bypass graft patients (r=0.62, P=0.01) but was not significantly correlated with calcification in non–coronary artery bypass graft explanted BHV.

Conclusions

Both increased BHV leaflet calcium levels and elevated oxidized amino acids were associated with bioprosthesis dysfunction necessitating reoperation; however, BHV calcium levels were not a determinant of implant duration, indicating a potentially important role for oxidized amino acid formation in BHV dysfunction.