Carpentier-Edwards Perimount Valves?Morphological Findings in Surgical Explants

Comparison of modes of failure and clinical outcomes between explanted porcine and bovine pericardial bioprosthetic valves

OBJECTIVE

To compare pathological and hemodynamic modes of failure and operative outcomes between explanted porcine and bovine pericardial bioprosthetic valves.

METHODS

Patients who underwent explantation of their bioprosthetic valves at Toronto General Hospital from 2007 to 2019 were identified. Retrospective chart review was conducted to attain demographic information, operative outcomes, and echocardiography and pathology reports.

RESULTS

A total of 278 patients underwent explantation of their porcine (n=183) or bovine pericardial (n=95) valves. A greater proportion of the porcine group had severe regurgitation, compared to the bovine group (45.3% vs. 19.8%, p<.001). Porcine valves had higher rates of cusp flail (19.4% vs. 3.3%, p<.001). The rates of moderate or worse stenosis were higher among bovine pericardial valves (37.9% vs. 15.8%, p<.001). On pathologic examination, the porcine valves exhibited more cusp tears (67.6% vs. 50.5%, p=.006), while higher incidences of calcification were found in the bovine group (p<.001). Rate of stroke was higher during the explantation procedure of the bovine valves (5.3% vs. 0.5%, p=.040).

CONCLUSIONS

The primary mode of failure was regurgitation in porcine valves due to cusp tears and stenosis in bovine valves due to calcification. Establishing a clear understanding of failure modes based on valve material may improve design and guide valve selection at the time of surgery.

A biomimetic multilayered polymeric material designed for heart valve repair and replacement

Materials currently used to repair or replace a heart valve are not durable. Their limited durability related to structural degeneration or thrombus formation is attributed to their inadequate mechanical properties and biocompatibility profiles. Our hypothesis is that a biostable material that mimics the structure, mechanical and biological properties of native tissue will improve the durability of these leaflets substitutes and in fine improve the patient outcome. Here, we report the development, optimization, and testing of a biomimetic, multilayered material (BMM), designed to replicate the native valve leaflets. Polycarbonate urethane and polycaprolactone have been processed as film, foam, and aligned fibers to replicate the leaflet's architecture and anisotropy, through solution casting, lyophilization, and electrospinning. Compared to the commercialized materials, our BMMs exhibited an anisotropic behavior and a closer mechanical performance to the aortic leaflets. The material exhibited superior biostability in an accelerated oxidization environment. It also displayed better resistance to protein adsorption and calcification in vitro and in vivo. These results will pave the way for a new class of advanced synthetic material with long-term durability for surgical valve repair or replacement.

Examination of Operatively-Excised Bioprostheses in the Mitral Valve Position to Determine the Reason for Dysfunction

Described herein are some clinical and morphologic findings in 23 patients who underwent operative replacement of a previously implanted bioprosthesis in the mitral valve position. Photographs of the operatively excised bioprostheses were provided in 15 (65%) of the 23 patients. A variety of causes were responsible for the bioprosthetic dysfunction. Twelve surgeons excised the dysfunctioning bioprostheses, an average of <2/surgeon, and a variety of techniques were employed to excise the bioprosthesis.

Biological Equivalence of GGTA-1 Glycosyltransferase Knockout and Standard Porcine Pericardial Tissue Using 90-Day Mitral Valve Implantation in Adolescent Sheep

Objective

There is growing interest in the application of genetically engineered reduced antigenicity animal tissue for manufacture of bioprosthetic heart valves (BHVs) to reduce antibody induced tissue calcification and accelerated structural valve degeneration (SVD). This study tested biological equivalence of valves made from Gal-knockout (GalKO) and standard porcine pericardium after 90-day mitral valve implantation in sheep.

Methods

GalKO (n = 5) and standard (n = 5) porcine pericardial BHVs were implanted in a randomized and blind fashion into sheep for 90-days. Valve haemodynamic function was measured at 30-day intervals. After explantation, valves were examined for pannus, vegetation, inflammation, thrombus, and tissue calcification.

Results

Nine of 10 recipients completed the study. There was no difference between study groups for haemodynamic performance and no adverse valve-related events. Explanted BHVs showed mild pannus integration and minimal thrombus, with no difference between the groups. Limited focal mineral deposits were detected by x-ray. Atomic spectroscopy analysis detected tissue calcium levels of 1.0 µg/mg ± 0.2 for GalKO BHVs and 1.9 µg/mg ± 0.9 for standard tissue BHVs (p = 0.4), considered to be both low and equivalent.

Conclusions

This is the first demonstration of biological equivalence between GalKO and standard pig pericardium. The GalKO mutation causes neither intrinsic detrimental biological nor functional impact on BHV performance. Commercial adaptation of GalKO tissue for surgical or transcatheter BHVs would remove the clinical disparity between patients producing anti-Gal antibody and BHVs containing the Gal antigen. GalKO BHVs may reduce accelerated tissue calcification and SVD, enhancing patient choices, especially for younger patients.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13239-021-00585-0.

Investigation of failure modes of explanted porcine valves in the mitral position

Background

Porcine valves are used for mitral valve replacement, but the limited long-term durability has restricted the application in younger patients. Degenerated porcine mitral valves were explanted to analyze the failure modes and damage characteristics.

Methods

Twelve porcine valves were explanted via secondary mitral valve replacement surgery. Microcomputed tomography scanning, morphological and pathological examinations were performed to classify the cusp tears, calcification, and pannus formation. The causes of valve deterioration were subsequently analyzed.

Results

The mean age at first implantation was 45.42±19.58 years (range, 11–64 years). The mean duration of implantation was 9.39±4.14 years (range, 4.25–18.75 years). The indications for first surgery were rheumatic heart disease in 8 patients (66.67%), infective endocarditis in 2 patients (16.67%), degenerative valvular disease in one patient (8.33%), and congenital heart disease in one patient (8.33%). Type I cusp tears and commissural dehiscence that occurred near the stent post position were found in 6 (50%) and 5 (41.67%) valves, respectively. Calcification was detected in 6 (50%) cases, and pannus was found in most valves (91.67%).

Conclusions

Leaflet damage occurred near the stent posts area was the main failure mode of porcine mitral valves in this study. Patients who undergo the first surgery at younger age, the higher prevalence rate of rheumatic heart disease, the structure of bioprosthetic porcine valve, and left ventricular stresses could be considered as the main factors causing valve deterioration.

Intentional Fracture of Bioprosthetic Valve Frames in Patients Undergoing Valve-in-Valve Transcatheter Pulmonary Valve Replacement

BACKGROUND

Percutaneous transcatheter pulmonary valve replacement (TPVR) has good clinical and hemodynamic outcomes in treating dysfunctional bioprosthetic valves (BPV) in the pulmonary position. Valve-in-valve therapy can further decrease the inner diameter (ID), potentially resulting in patient-prosthesis mismatch in patients with smaller BPVs.

METHODS AND RESULTS

To evaluate feasibility and outcomes of intentional BPV fracture to enlarge the pulmonary valve orifice with TPVR, 37 patients from 13 centers who underwent TPVR with intended BPV fracture were evaluated. A control cohort (n=70) who underwent valve-in-valve TPVR without attempted fracture was evaluated. BPV was successfully fractured in 28 patients and stretched in 5 while fracture was unsuccessful in 4. A Melody valve was implanted in 25 patients with fractured/stretched frame and a Sapien (XT 3) valve in 8. Among patients whose BPV was fractured/stretched, the final ID was a median of 2 mm larger (0-6.5 mm) than the valve's true ID. The narrowest diameter after TPVR in controls was a median of 2 mm smaller ( P<0.001) than true ID. Right ventricular outflow tract gradient decreased from median 40 to 8 mm Hg in the fracture group. Cases with fracture/stretching were matched 1:1 (weight, true ID) to controls. Post-TPVR peak gradient was lower but not significant (8.3±5.2 versus 11.8±9.2 mm Hg; P=0.070). There were no fracture-related adverse events.

CONCLUSIONS

Preliminary experience shows intentional fracture of BPV frame can be useful for achieving larger ID and better hemodynamics after valve-in-valve TPVR.

Mechanism of valve failure and efficacy of reintervention through catheterization in patients with bioprosthetic valves in the pulmonary position

BACKGROUND

Surgical and transcatheter bioprosthetic valves (BPVs) in the pulmonary position in patients with congenital heart disease may ultimately fail and undergo transcatheter reintervention. Angiographic assessment of the mechanism of BPV failure has not been previously described.

AIMS

The aim of this study was to determine the mode of BPV failure (stenosis/regurgitation) requiring transcatheter reintervention and to describe the angiographic characteristics of the failed BPVs and report the types and efficacy of reinterventions.

MATERIALS AND METHODS

This is a retrospective single-center review of consecutive patients who previously underwent pulmonary BPV placement (surgical or transcatheter) and subsequently underwent percutaneous reintervention from 2005 to 2014.

RESULTS

Fifty-five patients with surgical (41) and transcutaneous pulmonary valve (TPV) (14) implantation of BPVs underwent 66 catheter reinterventions. The surgically implanted valves underwent fifty reinterventions for indications including 16 for stenosis, seven for regurgitation, and 27 for both, predominantly associated with leaflet immobility, calcification, and thickening. Among TPVs, pulmonary stenosis (PS) was the exclusive failure mode, mainly due to loss of stent integrity (10) and endocarditis (4). Following reintervention, there was a reduction of right ventricular outflow tract gradient from 43 ± 16 mmHg to 16 ± 10 mmHg (P < 0.001) and RVp/AO ratio from 0.8 ± 0.2 to 0.5 ± 0.2 (P < 0.001). Reintervention with TPV placement was performed in 45 (82%) patients (34 surgical, 11 transcatheter) with no significant postintervention regurgitation or paravalvular leak.

CONCLUSION

Failing surgically implanted BPVs demonstrate leaflet calcification, thickness, and immobility leading to PS and/or regurgitation while the mechanism of TPV failure in the short- to mid-term is stenosis, mainly from loss of stent integrity. This can be effectively treated with a catheter-based approach, predominantly with the valve-in-valve technique.

Transcatheter Valve Underexpansion Limits Leaflet Durability: Implications for Valve-in-Valve Procedures

Transcatheter aortic valve (TAV) implantation within a failed bioprosthetic valve is a growing trend for high-risk patients. The non-compliant stent of the previous prosthesis may prevent full expansion of the TAV, which has been shown to distort the leaflet configuration, and has been hypothesized to adversely affect durability. In this study, TAV leaflet fatigue damage under cyclic pressurization in the setting of stent underexpansion by 0 (fully expanded), 1, 2 and 3 mm was simulated using finite element analysis to test this hypothesis. In the 2 and 3 mm underexpanded devices, the TAV leaflets exhibited severe pin-wheeling during valve closure, which increased leaflet stresses dramatically, and resulted in accelerated fatigue damage of the leaflets. The leaflet fatigue damage in the 1 mm underexpanded case was similar to that in the fully expanded case. Clinically a range of 10-15% underexpansion is generally considered acceptable; however, it was observed in this study that ≥2 mm (≥9.1%) underexpansion, will significantly impact device durability. Further study is necessary to determine the impact of various deployment conditions, i.e. non-uniform and non-circular deployments and different implantation heights, on differing TAV devices, but it is clear that the normal TAV leaflet configuration must be preserved in order to preserve durability.

Comparison of transcatheter aortic valve and surgical bioprosthetic valve durability: A fatigue simulation study

Transcatheter aortic valve (TAV) intervention is now the standard-of-care treatment for inoperable patients and a viable alternative treatment option for high-risk patients with symptomatic aortic stenosis. While the procedure is associated with lower operative risk and shorter recovery times than traditional surgical aortic valve (SAV) replacement, TAV intervention is still not considered for lower-risk patients due in part to concerns about device durability. It is well known that bioprosthetic SAVs have limited durability, and TAVs are generally assumed to have even worse durability, yet there is little long-term data to confirm this suspicion. In this study, TAV and SAV leaflet fatigue due to cyclic loading was investigated through finite element analysis by implementing a computational soft tissue fatigue damage model to describe the behavior of the pericardial leaflets. Under identical loading conditions and with identical leaflet tissue properties, the TAV leaflets sustained higher stresses, strains, and fatigue damage compared to the SAV leaflets. The simulation results suggest that the durability of TAVs may be significantly reduced compared to SAVs to about 7.8 years. The developed computational framework may be useful in optimizing TAV design parameters to improve leaflet durability, and assessing the effects of underexpanded, elliptical, or non-uniformly expanded stent deployment on TAV durability.

Carpentier-Edwards aortic pericardial bioprosthetic valve as a valid control in preclinical in vivo ovine studies

To progress into clinical practice, a bioprosthetic heart valve must first pass through the preclinical evaluation phase. The International Standards Organization (ISO) recommends implantation of concurrent controls in any evaluation of a new or modified heart valve. A total of 8 adult sheep underwent aortic valve replacement, receiving either the CE Perimount Magna 3000 aortic pericardial bioprosthetic valve or the CE Perimount RSR aortic pericardial bioprosthetic valve, Model 2800. We performed serial blood sampling, echocardiography, angiography and necropsy after euthanasia. All 8 sheep survived until the end of their study term. Our 2-dimensional echocardiographic analysis showed a mean pressure gradient of 37.4±6.0mmHg at 14 days and 37.0±5.9mmHg at 90 days; mean cardiac output was 10.0±2.8l/min at 14 days and 9.6±1.6l/min at 90 days. Angiography before euthanasia showed a mean aortic transvalvular gradient of 32.3±15.3mmHg. At euthanasia, we saw no evidence of calcification in any of the valves. In our study, we found that both models of the CE bioprosthetic heart valve we tested proved to be valid controls, in the aortic position, in sheep-with no evidence of calcification. Most important, the valves we tested had a few model-related problems, allowing a clear determination of their suitability for introduction into a clinical trial. Investigators now have additional insight into the safety of these 2 models of valves and perhaps will be able to reduce the number of controls implanted.

Successful treatment of failing biological prosthesis because of "Stent creep" with valve-in-valve transcatheter aortic valve implantation

INTRODUCTION

Stent creep is an uncommon mode of structural deterioration of bioprosthetic heart valves defined by a permanent inward deflection of the stent posts. This may occur because of valve over-sizing and leads to intrinsic valve stenosis. It has been described in older generation of bioprosthesis and was thought not to occur in modern devices.

METHODS

We describe three patients who were referred for bioprosthetic valve degeneration with presumed aortic stenosis. Investigations demonstrated mid valvular gradient predominantly because of stent creep. We performed valve-in-valve TAVI with Edward SAPIEN prosthesis.

RESULTS

Median age was 84 and logistic EuroSCORE 34.4. All patients had degenerated bioprosthesis with mean implant duration of 5.6 years. Two patients had Carpentier Edwards Perimount prosthesis (19 and 23 mm) and one patient had a Mitroflow (21 mm). Mean gradients were 33, 54, and 22 mm Hg. About 23 mm Edward SAPIEN valve was implanted in all cases with immediate improvement in haemodynamics with mean gradient reduction to 10, 17, and 8 mm Hg, respectively. The mean aortic valve area increased from 0.63 to 1.76cm(2) . There were no serious adverse events. The patients improved from NYHA III/IV to I/II post procedure and remain well at median follow-up of 24-months.

DISCUSSION

Stent creep is an uncommon mode of structural deterioration in bioprosthetic heart valves. It has been described in the previous generation of bioprosthesis. It is important to distinguish leaflet dysfunction and stent creep. By forcing the stent posts outwards a balloon expandable TAVI device can be used to treat this condition.

Transseptal strategy in retrograde transcatheter valve-in-valve implantation for failed surgical aortic bioprosthesis

We report a challenging case of transcatheter aortic valve-in-valve implantation in an elderly patient with failed surgical bioprosthesis. The transthoracic echocardiogram demonstrated a severe stenosis with a peak gradient of 142 mm Hg. The patient was a high-risk candidate for reoperative valve replacement; therefore, transfemoral implantation of a CoreValve (Medtronic Inc, Minneapolis, MN) was decided. During the procedure, we were unable to introduce the delivery catheter system across the bioprosthesis due to its poor alignment with the aortic annulus and the severity of the stenosis. With strategies involving transseptal puncture and externalization of a guidewire in an antegrade manner, the CoreValve was successfully positioned and deployed. This case illustrated the utility of transseptal strategies in challenging retrograde transcatheter aortic valve-in-valve implantation.

Simulation of long-term fatigue damage in bioprosthetic heart valves: effects of leaflet and stent elastic properties

One of the major failure modes of bioprosthetic heart valves (BHVs) is noncalcific structural deterioration due to fatigue of the tissue leaflets; yet, the mechanisms of fatigue are not well understood. BHV durability is primarily assessed based on visual inspection of the leaflets following accelerated wear testing. In this study, we developed a computational framework to simulate BHV leaflet fatigue, which is both efficient and quantitative, making it an attractive alternative to traditional accelerated wear testing. We utilize a phenomenological soft tissue fatigue damage model developed previously to describe the stress softening and permanent set of the glutaraldehyde-treated bovine pericardium leaflets in BHVs subjected to cyclic loading. A parametric study was conducted to determine the effects of altered leaflet and stent elastic properties on the fatigue of the leaflets. The simulation results show that heterogeneity of the leaflet elastic properties, poor leaflet coaptation, and little stent-tip deflection may accelerate leaflet fatigue, which agrees with clinical findings. Therefore, the developed framework may be an invaluable tool for evaluating leaflet durability in new tissue valve designs, including traditional BHVs as well as new transcatheter valves.

Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

Prosthetic heart valves are commonly used in the treatment of valvular heart disease. Mechanical valves are more durable than the bioprosthetic valves; however, the need for long-term anticoagulant therapy renders them unsuitable for some patient groups. In this paper we discuss the different types and models of bioprosthesis, and in particular, pericardial bioprosthesis. We also discuss the preimplantation preparation processes, as well as their postimplantation changes and modes of failure.

A case of Carpentier-Edwards pericardial bioprosthesis in mitral position explanted 22 years after implantation

A case of Carpentier-Edwards PERIMOUNT (CEP) mitral pericardial bioprosthesis explanted 22 years after the valve replacement is reported. This patient underwent the previous replacement at the age of 50. The extracted bioprosthesis showed three rigid leaflets, one of which had a tear causing severe mitral regurgitation. The X-ray demonstrated calcification of varied extent among these leaflets, ranging from none to severe. When leaflet calcification is suppressed, perhaps the lifespan of a CEP valve can be prolonged more than previously expected. When a literature search was conducted, this case was found to represent the longest reported interval from the implantation of a CEP valve in the mitral position to the explantation as a result of severe mitral regurgitation caused by structural valve deterioration (SVD).

Triple-valve treatment for prosthetic valve endocarditis occurring 20 years after implantation of a Carpentier-Edwards pericardial bioprosthesis in the aortic valve

A 68-year-old woman had undergone aortic valve replacement and open commissurotomy 20 years previously. At the beginning of 2008, fever, cold, and heart failure symptoms were noted. On blood culture, Streptococcus oralis was detected three times. Surgery was performed under a diagnoses of prosthetic valve endocarditis in the aortic valve, mitral stenosis and insufficiency, and tricuspid insufficiency. Techniques consisted of additional aortic valve replacement, mitral valve replacement, and tricuspid annuloplasty. Vegetation was macroscopically and pathologically observed in the extirpated Carpentier-Edwards pericardial bioprosthesis that had been placed in the aortic valve. There was no postoperative recurrent inflammatory response. The patient was discharged 32 days after surgery.