Structural deterioration of the Freestyle aortic valve: Mode of presentation and mechanisms

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.

Freestyle Aortic Bioprostheses in Patients 60 Years old and Younger

Evaluate outcomes of the Freestyle stentless aortic bioprosthesis in patients 60 years old and younger. All patients, 60 years old and younger, between January 1, 1998 to December 31, 2015 who underwent implantation of a Freestyle aortic valve at a single institution were reviewed. Medical records and telephone interviews were utilized for data collection. 515 patients were identified with an average age of 51.3 years. Mean follow up was 11.1 years. 225 full root replacements and 290 subcoronary implants were performed. Overall survival, including patients with concomitant procedures, at 15 years was 63.7% (95% CI 58.3-68.5). Isolated subcoronary implants (58%,167/290) had a 15-year survival of 71.6% (95% CI 62.6-78.7) vs 78.4% (95% CI 69.7, 84.9) for isolated root replacements (63%,141/225) which was not statistically significant (P = 0.397). No significant difference in operative SVD at 15 years occurred between full root replacements 37.6% (95% CI 27.2-50.2) vs subcoronary implants 39.4% (95% CI31.1, 49.0). 110 patients required reoperation solely for intrinsic SVD. 93% (102/110) failed due to aortic insufficiency. Of reoperative interventions for SVD, 37% (41/110) of patients required urgent reoperation and 4.5% (5/110) required emergent reoperation. Pseudoaneurysms developed in six of the full root replacements. Freestyle aortic valves have a high rate of acute failure requiring urgent or emergent reintervention in patients 60 years old and younger. This has led our group to shift practice away from their implantation.

Increased utilization of bioprosthetic aortic valve technology:Trends, drivers, controversies and future directions

Introduction: Bioprosthetic valves (BPV) implanted surgically or by transcatheter valve implantation (TAVI) comprise an overwhelming majority of substitute aortic valves implanted worldwide.Areas Covered: Prominent drivers of this trend are: 1) BPV patients have generally better outcomes than those with a mechanical valve, and remain largely free of anticoagulation and its consequences; 2) BPV durability has improved over the years; and 3) the expanding use of TAVI and valve-in-valve (VIV) procedures permitting interventional management of structural valve degeneration (SVD). Nevertheless, key controversies exist: 1) optimal anticoagulation regimens for surgical and TAVI BPVs; 2) the incidence, mechanisms and mitigation strategies for SVD; 3) the use of VIV for treatment of SVD, and 4) valve selection recommendations for difficult cohorts, (e.g. patients 50-70 years, patients <50, childbearing age women). This communication reviews trends in and drivers of BPV utilization, current controversies, and future directions affecting BPV use.Expert Opinion: Long-term data are needed in several areas related to aortic BPV use, including anticoagulation/antiplatelet therapy, especially following TAVI. TAVI and especially VIV durability and optimal use warrant will benefit greatly from long-term data. Certain populations may benefit from such high-quality data on multi-year outcomes, particularly younger patients.

Transcatheter valve-in-valve implantation versus surgical redo aortic root replacement in patients with degenerated freestyle aortic bioprosthesis

BACKGROUND

Transcatheter aortic valve-in-valve implantation (ViV TAVI) represents a new treatment option for patients with degenerated aortic bioprosthesis. Comparative data to redo surgical aortic valve replacement (redo SAVR) are limited.

OBJECTIVE

We investigated feasibility and outcome of ViV TAVI versus redo SAVR in patients with symptomatic degenerated Medtronic Freestyle aortic bioprosthesis (FSB).

METHODS

Between January 2002 and February 2020, 25 patients with failed FSB underwent ViV TAVI and 10 patients with failed FSB underwent redo SAVR. Endpoints were defined according to the Valve Academic Research Consortium-2 (VARC-2) criteria.

RESULTS

Age and logistic EuroSCORE II were higher in patients with ViV TAVI (75.4 ± 1.7 vs. 62.9 ± 5.1 years, p = .019; 11.5 ± 1.6 vs. 5.6 ± 5.6%, p = .007). Valve implantation was successful in all cases. Mean transvalvular pressure gradients were significantly lower in patients with redo SAVR than ViV TAVI (7.6 ± 1.0 vs. 10.3 ± 0.8 mmHg, p = .037). Aortic valve regurgitation was absent in 91% and 100% of patients with ViV TAVI and redo SAVR, respectively. Thirty-day mortality rates were 12% in the ViV TAVI cohort versus 0% in the redo SAVR cohort (p = .542). Within the first year after hospital discharge, one patient after ViV TAVI had redo surgical intervention.

CONCLUSIONS

ViV TAVI and redo SAVR lead to excellent functional results in patients with degenerated FSB. Post-procedural early complications must be considered particularly in patients with ViV TAVI because of higher clinical risk profiles.

Structural valve deterioration and mode of failure of stentless bioprosthetic valves

BACKGROUND

Aortic stentless bioprosthetic valve (SLBPV), either porcine or pericardial, minimizes transvalvular gradient and favors regression of left ventricular hypertrophy. The drawback consists of longer time for suturing. While structural valve deterioration (SVD) in stented porcine and pericardial BPVs has been extensively investigated, less information is available on SLBPVs.

MATERIAL AND METHODS

We studied 82 SLBPVs explants, either porcine (Toronto SPV, [St. Jude Medical, MN, USA], CryolifeO'Brien Model 300 and CryoLife-O'Brien [Cryolife International, GA, USA], BioCor PVS [St. Jude Medical, MN, USA] Prima and Prima Plus [Edwards Lifesciences Corp. One Edwards Way, CA, formerly Baxter Inc, CA, USA]) or pericardial ([Pericarbon Freedom and Freedom Solo [Sorin-Biomedica, S.p.A., Saluggia, Italy]).

RESULTS

By excluding cases with leak and endocarditis, we focused the investigation on 46 SLBPVs, which failed because of SVD. Gender was male in 29 (63%). Mean age of patients at time of implant was 59.8 years. Postoperative time of SVD was 115.0 months for porcine and 79.0 months for pericardial SLBPVs. Dysfunction requiring reoperation was mainly incompetence for porcine and stenosis for pericardial SLBPVs. Even pinpoint mineralization at the commissures resulted in sudden cusp tearing and incompetence. Cuspal atheromasia accounted for cusp tearing even in the absence of calcification. Mineralization showed progression with time in pericardial but not in porcine SLBPVs.

CONCLUSIONS

Tissue mineralization remains the nightmare also of SLBPVs, with the peculiar features of pinpoint calcific deposits at commissures, tearing and abrupt incompetence in porcine SLBPVs and of massive cuspal mineralization and stenosis in pericardial SLBPVs.

Long-term clinical outcomes of the Toronto stentless porcine valve: 15-year results from dual centers

BACKGROUND AND AIM OF THE STUDY

The purpose of this study is to examine the long-term durability of the Toronto stentless porcine valve (SPV) in the aortic position (St Jude Medical, Minneapolis, MN).

METHODS

We assessed the long-term clinical outcomes of 515 patients with aortic valve replacement (AVR) with the Toronto SPV from 1987 to 2001 at two centers, excluding early (<30 days) death. Median follow-up was 11.5 years (maximum 19.0 years).

RESULTS

Average age was 64.2 ± 10.8 years, and females were 34% (173/515). The incidence of prosthesis-patient mismatch was low, 10.9%. Overall survival was 90.7 ± 1.3%, 75.4 ± 2.0%, and 56.8 ± 3.2% at 5, 10, and 15 years, respectively after surgery. Over the follow-up duration, 116 patients (23%) underwent repeated AVR: 90 for structural valve deterioration (SVD), 12 for endocarditis, 10 nonstructural valve dysfunction (10 aortic regurgitation due to aorta dilatation), and four for other reasons. The cumulative incidence of repeated AVR with death as a competing risk was 1.4% (95% confidence interval [CI], 0.6-2.7), 11.1% (95% CI, 8.4-14.2), and 34.4% (95% CI, 28.8-40.2) at 5, 10, and 15 years, respectively. Reoperative mortality was 5.2% (6/116). In SVD, the regurgitation type was dominant (82%).

CONCLUSIONS

The Toronto SPV is associated with excellent survival and durability during the first decade of follow-up. However, regurgitation type of SVD increases from 10 years after operation with acceptable reoperative mortality. These findings may assist with prosthesis selection and reintervention strategy for failing stentless bioprosthesis.

Midterm Outcomes for Valve-in-Valve Transcatheter Aortic Valve Replacement in the Failed Freestyle Bioprosthesis

BACKGROUND

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is acceptable in patients at high risk for reoperation. Studies suggest that ViV TAVR in stentless valves may be technically more challenging. This study sought to evaluate midterm outcomes for ViV TAVR in the degenerative Freestyle ((Medtronic, Minneapolis, MN)) stentless bioprosthesis.

METHODS

Between October 2014 and January 2019, 56 patients underwent ViV TAVR for a failed Freestyle valve at a single institution using a commercially available self-expanding transcatheter aortic valve. Patient baseline characteristics and clinical outcomes data were collected retrospectively. Valve Academic Research Consortium-2 definitions were applied.

RESULTS

Mean patient age was 75 ± 8 years and The Society of Thoracic Surgeons mean risk score was 9% ± 8%. The predominant mode of Freestyle valve failure was regurgitation (77%), and 36 patients (64%) required urgent intervention for refractory acute heart failure. Device success using a self-expanding TAVR was 82%, with 6 cases (11%) requiring deployment of two transcatheter valves. There were 3 operative mortalities (5%). At 30-day follow-up, no patient had greater than moderate perivalvular regurgitation. Device success was higher in the later patients compared with patients done earlier (P = .02). Mean aortic valve gradients at 30 days and 1 year were 11 ± 8 and 9 ± 8 mm Hg, respectively. For patients alive beyond day 30, 3-year survival was 82%.

CONCLUSIONS

Performing ViV TAVR in the Freestyle valve using a self-expanding transcatheter valve presents a technical challenge, but may be feasible with good midterm results. Procedural success is associated with an early hazard learning curve.

Successful implantation of self-expanding valve for a failed stentless prosthesis

Valve-in-valve transcatheter aortic valve implantation is currently used for failed bioprosthesis. The use of a transcatheter prosthesis in a regurgitant noncalcified root implanted Medtronic Freestyle prosthesis is particularly challenging. We present a successful transaxillary valve-in-valve implantation of a self-expandable transcatheter aortic valve prosthesis in a failed Freestyle bioprothesis implanted eleven years earlier. Tips and tricks are discussed.

Hemodynamic and Imaging Assessment of Transcatheter Aortic Valve Replacement with the Inovare® Proseal using Multislice Computed Tomography

Objective

To evaluate the hemodynamic performance (i.e., gradients and paravalvular leakage [PVL]) of the new and experimental Braile Inovare^® Proseal. Additionally, we aimed to assess pre and postoperatively the aortic annulus and the transcatheter prosthesis using multislice computed tomography (MSCT).

Methods

Patients were selected by a multidisciplinary heart team and referred for transcatheter aortic valve replacement (TAVR). MSCT was performed before and after surgery. Measurements of the aortic valve and prosthesis were conducted and correlated with the valve gradient and residual PVL.

Results

Twenty-one patients were selected for the protocol. Patients had a mean age of 79 years and 38% of them were of female sex. The mean EuroSCORE II value was 12.5%±10.8. Mean gradient was reduced from 45.8±11.04 mmHg to 5.59±2.61 mmHg and there were no instances of PVL worse than mild. There were no cases of coronary obstruction or procedural death. Circularity was present in all prostheses evaluated. Circularity indexes for the prostheses were: inflow 0.05±0.03, middle third 0.04±0.02, and outflow 0.04±0.02 (P=0.08). The mean distance between the prosthesis and the left and right coronary ostia were 14.8 mm±3.3 and 17.3 mm±3, respectively. Oversizing was appropriate with a mean of 22.14%±6%.

Conclusion

Braile Inovare^® Proseal transcatheter device has demonstrated low gradients with low rates of PVL. Oversizing by annular measurements was adequate. MSCT was adequate to evaluate device sizing and has demonstrated preserved expansibility and circularity in the evaluated cases.

Experimental analysis of pulsatile flow characteristics in prosthetic aortic valve models with stenosis

Bioprosthetic valves are widely used for aortic valve replacements for patients with severe aortic diseases. However, tissue-engineered leaflets normally deteriorate over time due to calcification, leading to life-threatening conditions that would require re-operation. The hemodynamics induced by a prosthetic stenosis is complicated and not fully understood. This in vitro experimental study focuses on the fluid dynamics of two aortic valve models with different prosthetic stenosis conditions. An in vitro cardiovascular flow simulator was utilized to provide the pulsatile physiological flow conditions. Phase-locked particle image velocimetry (PIV) and high-frequency pressure sensors were employed to measure the flow fields and pressure waveforms. Pressure data were evaluated for the two models representing moderate and severe stenosis conditions, respectively. The severe prosthetic stenosis induced a prolonged ejection period and increased acceleration time ratio. PIV results suggest the severe prosthetic stenosis resulted in a two-fold increase in peak jet velocity and a three-fold increase in peak turbulence kinetic energy compared to the moderate stenosis case. The severe stenosis also caused rapid expansion of the jet downstream of the valve orifice and increased eccentricity of the jet flow. The maximum Reynolds shear stress in the severe stenosis case was found similar to the bileaflet mechanical valve reported by previous literature, which was below the risk threshold of blood cell damage but could potentially increase the risks of platelet activation and aggregation.

Influence of Age on Longevity of a Stentless Aortic Valve

BACKGROUND

The longevity of a stentless valve in a younger population (20-60 years old) is unknown.

METHODS

From 1992 to 2015, 1947 patients underwent aortic valve/root replacement for aortic stenosis, insufficiency, root aneurysm, or aortic dissection with stentless bioprostheses (median size, 26 mm). At operation 105 patients were <40 years old, 528 were 40 to 59, 860 were 60 to 74, and 454 were ≥75 years. The data were obtained through chart review, administered surveys, and the National Death Index.

RESULTS

The 30-day mortality rate was 2.6%. During follow-up 807 patients (41%) died before reoperation, 993 (51%) were alive without reoperations because of deterioration, and 113 patients (5.8%) underwent reoperation for structural valve deterioration. After adjusting death and reoperation for non-structural valve deterioration causes as competing risks, the cumulative incidence of reoperation was significantly different between the younger groups (<40, 40-59) and the older groups (60-74, ≥75; P < .0001) but not inside the younger (<40 vs 40-59) or older (60-74 vs ≥75) group. The significant hazard ratio of reoperation for <40 versus ≥75 years of age was 12, <40 versus 60 to 74 was 4, 40 to 59 versus 60 to 74 was 3, and 40 to 59 versus ≥75 was 9 (P ≤ .01). The 10- and 15-year survival in the entire cohort was 53% and 29%, respectively.

CONCLUSIONS

The stentless aortic valve provides satisfactory durability as a conduit for aortic valve/root replacement for patients who prefer a bioprosthesis. However it should be judiciously considered for patients younger than 60 years because of an increased incidence of reoperation for structural valve deterioration.

Bioprosthetic Aortic Valve Replacement in <50 Years Old Patients - Where is the Evidence?

Aortic valve disease is one of the most common valvular heart diseases in the cardiovascular category. Surgical replacement of the diseased aortic valve remains the definitive intervention for most diseases.

There is a clear consensus that in young patients who require aortic valve replacement, a mechanical prosthesis is the preferred choice due to its durable prosthesis without fear of wear and tear over time. However, this comes at the expense of increased risk of bleeding and thromboembolic events; in addition, there is a lack of strict evidence in using bioprosthesis in patients younger than 50 years. The objective of this review article is to assess the current evidence behind using bioprosthetic aortic valve in this young cohort.

Comparison of tensile properties of xenopericardium from three animal species and finite element analysis for bioprosthetic heart valve tissue

Bioprosthetic heart valves still have poor long-term durability due to calcification and mechanical failure. The function and performance of bioprostheses is known to depend on the collagen architecture and mechanical behavior of the target tissue. So it is necessary to select an appropriate tissue for such prostheses. In this study, porcine, equine, and bovine pericardia were compared histologically and mechanically. The specimens were analyzed under light microscopy. The planar biaxial tests were performed on the tissue samples by applying synchronic loads along the axial (fiber direction) and perpendicular directions. The measured biaxial data were then fitted into both the modified Mooney-Rivlin model and the anisotropic four parameter Fung-type model. The modified Mooney-Rivlin model was applied to the modeling of the bovine, equine, and porcine pericardia using finite element analysis. The equine pericardium illustrated a wavy collagen bundle architecture similar to bovine pericardium, whereas the collagen bundles in the porcine pericardium were thinner and structured. Wavy pericardia may be preferable candidates for transcutaneous aortic valves because they are less likely to be delaminated during crimping. Based on the biaxial tensile test, the specimens indicated some degree of anisotropy; the anisotropy rates of the equine specimens were almost identical, and higher than the other two specimens. In general, porcine pericardium appeared stiffer, based on the greater strain energy magnitude and the average slope of the stress-stretch curves. Moreover, it was less distensible (due to lower areal strain) than the other two pericardial tissues. Furthermore, the porcine model induced localized high stress regions during the systolic and diastolic phases of the cardiac cycle. However, increased mechanical stress on the bioprosthetic leaflets may cause tissue degeneration and reduce the long-term durability of the valve. Based on our observations, the pericardial specimens behaved as anisotropic and nonlinear tissues-well-characterized by both the modified Mooney-Rivlin and the Fung-type models. The results indicate that, compared to bovine pericardium, equine tissue is mechanically and histologically more appropriate for manufacturing heart valve prostheses. The results of this study can be used in the design and manufacture of bioprosthetic heart valves.

Complementary Role of the Computed Biomodelling through Finite Element Analysis and Computed Tomography for Diagnosis of Transcatheter Heart Valve Thrombosis

Introduction

The TAVR procedure is associated with a substantial risk of thrombosis. Current guidelines recommend catheter-based aortic valve implantation for prohibitive-high-risk patients with severe aortic valve stenosis but acknowledge that the aetiology and mechanism of thrombosis are unclear.

Methods

From 2015 to 2018, 607 patients with severe aortic valve stenosis underwent either self-expandable or balloon-expandable catheter-based aortic valve implantation at our institute. A complementary study was designed to support computed tomography as a predictor of complications using an advanced biomodelling process through finite element analysis (FEA). The primary evaluation of study was the thrombosis of the valve at 12 months.

Results

At 12 months, 546 patients had normal valvular function. 61 patients had THVT while 6 showed thrombosis and dislodgement with deterioration to NYHA Class IV requiring rehospitalization. The FEA biomodelling revealed a strong link between solid uncrushed calcifications, delayed dislodgement of TAVR and late thrombosis. We observed an interesting phenomenon of fibrosis/calcification originating at the level of the misplaced valve, which was the primary cause of coronary obstruction.

Conclusion

The use of cardiac CT and predictive biomodelling should be integrated into routine practice for the selection of TAVR candidates and as a predictor of negative outcomes given the lack of accurate investigations available. This would assist in effective decision-making and diagnosis especially in a high-risk cohort of patients.

Ascending Aortic Replacement and Sutureless Valve in a Failed Stentless Aortic Prosthesis: A Bailout Option

Aortic valve replacement with a Perceval sutureless bioprosthesis is a viable rescue option for a failed aortic stentless prosthesis. However, a dilated sinotubular junction and ascending aorta are reported as a contraindication for this technique. We describe an aortic sutureless valve implantation in a patient with a dilated ascending aorta and small aortic root after Dacron graft replacement of the ascending aorta in a failed aortic stentless bioprosthesis.

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro. Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo. It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a 'peel-back' leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 ± 2.04% versus circular = 11.77 ± 1.61%, p = 0.0014, hypertension: eccentric = 15.07 ± 1.13% versus circular = 13.56 ± 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.

Circulating Lp-PLA2 is associated with high valvuloarterial impedance and low arterial compliance in patients with aortic valve bioprostheses

BACKGROUND

We previously reported that plasma Lp-PLA2 was associated with aortic valve disease progression and degeneration of bioprostheses. Low systemic arterial compliance and high valvuloarterial impedance (Z(va)) are predictors of poor survival in patients with aortic valve disease. However, the prevalence of high Z(va) after AVR is largely unknown and whether Lp-PLA2 could predict Z(va) has not been documented. We investigated the relationships between plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) mass and activity and valvuloarterial impedance (Z(va)), an index of global LV hemodynamic load, in patients that underwent aortic valve replacement (AVR).

METHODS

A total of 195 patients with aortic bioprostheses underwent echocardiographic assessment of the prosthetic aortic valve function 8±3.4 years after AVR. Lp-PLA2 mass and activity were measured.

RESULTS

In this group of patients, the mean Z(va) was elevated (5.73±1.21 mm Hg·ml(-1)·m(2)). In univariate analyses, Lp-PLA2 mass (p=0.003) and Lp-PLA2 activity (p=0.046) were associated with Z(va). After adjustment for covariates including age, gender, clinical risk factors, anti-hypertensive medications, body mass index and prosthesis size, Lp-PLA2 mass was associated with high Z(va) (≥4.5 mm Hg·ml(-1)·m(2)) (OR: 1.29, 95%CI: 1.10-1.53; p=0.005) and was inversely related with the systemic arterial compliance (β=-0.01, SEM=0.003; p=0.003).

CONCLUSIONS

An increased Z(va), an index of excessive hemodynamic load, was highly prevalent 8-year post-AVR and was independently related to circulating Lp-PLA2.

Long Term Outcomes Following Freestyle Stentless Aortic Bioprosthesis Implantation: An Australian Experience

BACKGROUND

The Freestyle stentless bioprosthesis (FSB) has been demonstrated to be a durable prosthesis in the aortic position. We present data following Freestyle implantation for up to 10 years post-operatively and compare this with previously published results.

METHODS

A retrospective cohort analysis of 237 patients following FSB implantation occurred at five Australian hospitals. Follow-up data included clinical and echocardiographic outcomes.

RESULTS

The cohort was 81.4% male with age 63.2±13.0 years and was followed for a mean of 2.4±2.3 years (range 0-10.9 years, total 569 patient-years). The FSB was implanted as a full aortic root replacement in 87.8% patients. The 30-day all cause mortality was 4.2% (2.0% for elective surgery). Cumulative survival at one, five and 10 years was 91.7±1.9%, 82.8±3.8% and 56.5±10.5%, respectively. Freedom from re-intervention at one, five and 10 years was 99.5±0.5%, 91.6±3.7% and 72.3±10.5%, respectively. At latest echocardiographic review (mean 2.3±2.1 years post-operatively), 92.6% had trivial or no aortic regurgitation. Predictors of post-operative mortality included active endocarditis, acute aortic dissection and peripheral vascular disease.

CONCLUSIONS

We report acceptable short and long term outcomes following FSB implantation in a cohort of comparatively younger patients with thoracic aortic disease. The durability of this bioprosthesis in the younger population remains to be confirmed.

Pseudoaneurysm formation after medtronic freestyle porcine aortic bioprosthesis implantation: a word of caution

BACKGROUND

A growing literature describes aneurysmal deterioration after implantation of the stentless porcine aortic Medtronic Freestyle bioprosthesis (MFB; Medtronic Inc, Minneapolis, MN), with some suggesting inadequate tissue fixation with immune response as a cause. However, disjointed reports make the significance of these findings difficult to interpret. We address this concern by aggregating available data.

METHODS

We reviewed institutional data, the Food and Drug Administration's Manufacturer and User Facility Device Experience registry, and the medical literature for mention of aneurysm or pseudoaneurysm after MFB. Case details were aggregated, and the rate of aneurysmal deterioration was estimated. Immunohistopathologic examination of institutional explanted specimens was performed to elucidate a cause.

RESULTS

We found 42 cases of aneurysmal deterioration with adequate detail for analysis; all occurred with full root replacement and valve sizes ranging from 23 to 29 mm. The rate of aneurysmal deterioration considering all data sources was 1.1% (9 of 851; 95% confidence interval, 0.5% to 2.0%) vs 4.7% (4 of 86; 95% confidence interval, 1.3% to 11.5%) at our institution, where yearly surveillance imaging is performed. Rate of aneurysmal deterioration appeared constant until 5 years after the operation; however, events are reported out to 10 years. Consistent with previous reports, histopathology demonstrated an immune cell infiltrate in areas of MFB wall breakdown.

CONCLUSIONS

Aneurysmal deterioration is an increasingly described complication of MFB implantation as a full root, with an incidence as high as 4.7%. Given the observed immune reaction and lack of occurrence in smaller (19-mm and 21-mm) valve sizes, inadequate pressure fixation of larger valves is a potential etiology. Patients with MFB require annual surveillance imaging, and consideration of this complication should factor into preoperative decision making because treatment mandates redo root replacement, which may not be feasible in high-risk patients.

The freestyle aortic bioprosthesis: a systematic review

BACKGROUND

The Medtronic Freestyle bioprosthesis (FSB) provides an alternative to other prostheses for both aortic valve and aortic root surgery. This paper is a systematic review of the post-operative outcomes in patients with aortic valve and/or aortic root disease following FSB implantation.

METHODS

Electronic databases were searched for primary analysis, prospective randomised studies comparing the FSB with an alternative aortic prosthesis were included. Additionally, case series that included data for at least 100 individual operated patients were used for secondary analysis.

RESULTS

Among three identified randomised studies, 199 FSB cases were compared with homografts, and stented and an alternative stentless bioprosthesis. The FSB showed comparable hospital mortality (4.5% vs. 5.3%) and eight-year actuarial survival (80±5.0% versus 77±6.0%) with the homograft (respectively) and comparable reduction in left ventricular mass index relative to other prosthesis types. Over 6000 individual patients were included in the selected 15 case series. Weighted mean operative mortality, neurological event rate and five-year actuarial survival was 5.2%, 5.5% and 77.8%, respectively.

CONCLUSION

The FSB performed comparably against alternative prostheses regarding in-hospital mortality, long-term survival and reduction in left ventricular mass index. Included case series demonstrated robust post-operative outcomes in both the short and long term.

Structural valve deterioration after aortic valve replacement with Medtronic freestyle stentless porcine aortic root bioprostheses

The Medtronic freestyle aortic root bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA) is a stentless valve with an effective orifice area that is larger than that observed on other bioprostheses. However, there have been sporadic reports of structural valve deterioration (SVD), such as aortic root wall rupture, leaflet tearing, and pseudoaneurysm formation. We report five cases of SVD of freestyle aortic root bioprostheses. doi: 10.1111/jocs.12235 (J Card Surg 2014;29:22-25)

Rupture of valsalva sinus after aortic root replacement with freestyle stentless bioprosthesis

We report a case of aortic wall rupture in a patient with a Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) after full root implantation. A 68-year-old man who underwent aortic root replacement with a Freestyle bioprosthesis 12 years prior was found to have a large pseudoaneurysm originating from the ruptured noncoronary porcine aortic sinus. A reoperation for aortic root replacement was successfully performed. Despite excellent durability of porcine aortic root bioprostheses, several cases with a ruptured aortic wall have been reported. Degeneration of the elastic tissue and inflammatory reactions may be the main mechanism of this potentially catastrophic complication.

Long-Term Clinical and Echocardiographic Follow-Up of the Freestyle Stentless Aortic Bioprosthesis

Background—

Stentless aortic bioprostheses were designed to provide enhanced hemodynamic performance and potentially greater longevity. The present report describes the outcomes of patients with the Freestyle stentless bioprosthesis followed for ≤18 years.

Methods and Results—

Between 1993 and 2011, 430 patients underwent primary aortic valve replacement with a Freestyle bioprosthesis in the subcoronary position. Mean age was 68.2±8.2 years. All of the clinical and echocardiographic data were collected prospectively. Mean overall follow-up was 9.1±4.4 years and was complete in all of the patients. In-hospital mortality was 3.5% (n=15). Overall, 10- and 15-year survival were 60.7% and 35.0%, respectively. Fifty-one patients required reoperation during follow-up, including 27 for structural valve deterioration (SVD). Overall, freedom from reoperation was 91.0% and 75.0% at 10 and 15 years, whereas freedom from reoperation for SVD was 95.9% and 82.3%, respectively. At 10 and 15 years, freedom from reoperation for SVD was 94.0% and 62.6% for patients <60 years of age and 96.3% and 88.4% for patients ≥60 years of age ( P =0.002). The median time to explant for SVD was 10.7 years. SVD presented mostly as acute, severe aortic insufficiency attributed to leaflet tear (77.8%). The independent risk factors for reoperation for SVD were age <60 years ( P =0.001) and dyslipidemia ( P =0.02).

Conclusions—

Aortic valve replacement with the Freestyle bioprosthesis in a subcoronary position provides good long-term clinical and echocardiographic outcomes for patients >60 years of age. Severe aortic insufficiency with leaflet tear is the major mode of SVD leading to reoperation in these patients.

Early stenosis of stentless aortic valve prosthesis: a word of caution

Early stenosis of stentless bioprosthetic valves is rarely reported. In this report, we discuss a 75-year-old woman who presented with signs of congestive heart failure 5 months after a stentless aortic valve replacement, complicated by postoperative heparin-induced thrombocytopenia. Intraoperative findings were highly unusual, consisting of a fibrous band in the subvalvular apparatus linking the interventricular septum to the free wall of the left ventricle, resulting in significant left ventricular outflow tract obstruction. The possible causes of the fibrous band are discussed.

Early Doppler-echocardiography evaluation of Carpentier-Edwards Standard and Carpentier-Edwards Magna aortic prosthetic valve: comparison of hemodynamic performance

OBJECTIVES

This study was designed to describe Doppler-echocardiography values of Carpentier-Edwards Perimount Standard (CEPS) and Carpentier-Edwards Perimount Magna (CEPM) aortic prosthetic valves, evaluated by a single, experienced echo-laboratory, early in the postoperative phase.

METHODS

Three-hundred-seventy-seven consecutive patients, who had had a CEPS or a CEPM implanted in our Hospital due to aortic stenosis and/or insufficiency, underwent baseline Doppler echocardiography evaluation within 7 days after surgery. Hemodynamic performances of CEPS and CEPM were accurately described, evaluating flow-dependent (transprosthetic velocities and gradients) and flow-independent (effective orifice area, indexed effective orifice area and Doppler velocity index) Doppler-echocardiography parameters.

RESULTS

Out of the 377 patients 48.8% were men (n = 184), mean age was 74.63 ± 6.77 years, mean BSA was 1.78 ± 0.18 m2, mean ejection fraction was 57.78 ± 8%. Two-hundred and sixty two CEPS and 115 CEPM were implanted. Comparing size-by-size CEPS with CEPM, both prostheses showed a good hemodynamic profile, with fairly similar values of pressure gradients (PGmax and mean, in mmHg, = 37,18 ± 11.57 and 20.81 ± 7.44 in CEPS n°19 compared to 32,47 ± 7,76 and 17,67 ± 4.63 in CEPM n°19 and progressively lower in higher sized prostheses, having PGmax and mean 15 ± 3,16 and 9.15 ± 1,29 in CEPS n°29 compared to 15,67 ± 1,53 and 9 ± 1 in CEPM n°29) and EOAi (being 0,65 ± 0,33 cm²/m² in CEPS n°19 compared to 0,77 ± 0,29 cm²/m² in CEPM n°19 and progressively higher in higher sized prostheses, being 1,28 ± 0,59 cm²/m² in CEPS n°29 compared to 1,07 ± 0,18 cm²/m² in CEPM n°29), the latter resulting, however, basically less flow obstructive.

CONCLUSIONS

Our data confirm the good hemodynamic performance of both aortic bioprostheses and the more favourable hemodynamic profile of CEPM compared to CEPS, pointing out the need to perform routinely an accurate baseline Doppler-echocardiography evaluation early after surgery to allow an adequate interpretation of data at follow-up.

Aortic regurgitation due to perforation of the right coronary cusp 10 years after implantation of a freestyle stentless bioprosthesis

Valve deterioration following aortic valve replacement using the Freestyle stentless bioprosthesis is related to cusp tear, operative injury, or infection. We report a patient with aortic regurgitation due to perforation of the right coronary cusp 10 years after implantation of a Freestyle stentless bioprosthesis in the absence of endocarditis.

Stentless aortic valve replacement: an update

Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Optimizing hemodynamics to prevent patient–prosthetic mismatch and improve durability, stentless bioprostheses use was revived in the early 1990s. The purpose of this review is to provide a current overview of stentless valves in the aortic position. Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement (AVR), though stentless AVR required longer cross-clamp and cardiopulmonary bypass time. Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular (LV) mass regression compared with stented AVR. However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier–Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Freedom from reoperation at 12 years in Toronto stentless porcine valves ranged from 69% to 75%, which is much lower than for Carpentier–Edwards Perimount valves. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O’Brien valves also have shorter durability compared with stent valves. Actuarial freedom from reoperation was 44% at 10 years. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts. There was no level I or IIa evidence of more effective orifice area, mean pressure gradient, LV mass regression, surgical risk, durability, and late outcomes in stentless bioprostheses. There is no general recommendation to prefer stentless bioprostheses in all patients. For new-generation pericardial stentless valves, follow-up over 15 years is necessary to compare the excellent results of stented valves such as the Carpentier–Edwards Perimount and Hancock II valves.

Aortic valve translocation for treatment of a deteriorated stentless valve

A 54-year-old woman was admitted to our hospital with recurrent chest pain for 1 month. She had a history of aortic root replacement with a stentless valve following aortic valve replacements done twice 12 years ago, and coronary artery bypass grafting 6 years ago. The stentless valve was implanted with the full-root technique. After admission, she was diagnosed with a saphenous vein graft aneurysm in the proximal anastomotic site and severe aortic regurgitation due to stentless valve deterioration. These lesions were successfully treated using aortic valve translocation. The advantage of this procedure is that it avoids dissection and removal of the stentless valve implanted using the full-root technique. Aortic valve translocation can be one of useful alternatives for stentless valve reoperation.

Truly stentless autologous pericardial aortic valve replacement: an alternative to standard aortic valve replacement

OBJECTIVE

The aim of this study was to determine the feasibility and durability of truly stentless aortic valve replacement using autologous pericardium sutured directly onto the aortic wall.

METHODS

Eleven patients (mean age, 55.9 years) requiring aortic valve replacement were recruited. A circular piece of pericardium about 8 cm in diameter was harvested and treated in 0.6% glutaraldehyde for 10 minutes. The aortic valve was excised and, with the use of specially designed instruments (CardioMend LLC, Santa Barbara, Calif), the sinotubular junction was sized and the pericardium was tailored to the required size and shape and then sutured directly onto the aortic wall. The reconstructed valve was assessed directly and by echocardiography at the end of the operation; it was assessed by echocardiography and cardiac magnetic resonance imaging at 6 months and yearly. Computed tomographic scan of the aortic valve to assess for valve calcification was performed at last follow-up.

RESULTS

Hospital mortality was 0%. Mean follow-up was 6.5 years (range, 5.3-7.5 years). Freedom from structural valve deterioration, thromboembolism, endocarditis and reoperation was 100%, 100%, 72.7%, and 63.6%, respectively. There were 4 reoperations at 4, 13, 15, and 46 months, 3 of them owing to endocarditis and 1 owing to technical failure noted at the time of surgery. The remaining 7 patients are alive and well with a mean New York Heart Association class of 1.3 and normally functioning aortic valves with no calcification.

CONCLUSIONS

Truly stentless aortic valve replacement using autologous pericardium sutured directly onto the aortic wall is safe and feasible and has excellent durability up to 7.5 years with no calcification.

Early Doppler-echocardiography evaluation of 597 prosthetic aortic valves

OBJECTIVES

This study was designed to describe the Doppler-echocardiography normal values in the early postoperative phase for Carpentier-Edwards Perimount Aortic Heart Valve bioprosthesis (CEP), St. Jude Medical (SJM) or Medical Regent (SJMR) Mechanical Heart Valves, evaluated by a single experienced echo-laboratory.

METHODS

Five hundred and ninety-seven consecutive patients in our hospital, who had had a CEP, a SJM or SJMR-17 mm implanted due to aortic stenosis, underwent a control Doppler-echocardiography evaluation 4-7 days after surgery. Hemodynamic performance of SJM, SJMR and CEP were accurately described, evaluating flow-dependent (trans-prosthetic velocities and gradients) and flow-independent (effective orifice area, indexed effective orifice area and Doppler velocity index) Doppler-echocardiography parameters.

RESULTS

Of the 597 patients 50.6% were women (n = 302). Mean age was 66.3 +/- 11.7 years. Mean body surface area (BSA) was 1.76 +/- 0.22 m. Mean ejection fraction was 55.3 +/- 10.3%. Two hundred and sixty CEPs and 337 St. Jude mechanical valves (301 SJM and 36 SJMR size-17) were implanted. Comparing size-by-size SJM to CEP, the former were basically less flow obstructive.

CONCLUSION

Our data confirm the wide range of variability, pointing out the need to perform routinely an accurate baseline Doppler-echocardiography evaluation of the hemodynamic profile of prosthetic aortic valves, including flow-dependent and independent parameters, to allow an adequate interpretation at follow-up.