Evaluation of Hemodynamic Performance of Aortic Valve Bioprostheses in a Model of Oversizing

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

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

Impact of postoperative patient-prosthesis mismatch as a risk factor for early structural valve deterioration after aortic valve replacement with Trifecta bioprosthesis

BACKGROUND

Several studies have reported high rates of structural valve deterioration (SVD) in the Trifecta valves. Herein, we analyzed the midterm results of the Trifecta valve and risk factors for early SVD.

METHODS

We retrospectively reviewed the records of 110 patients who had undergone Trifecta implantation between January 2012 and December 2017.

RESULTS

We encountered seven cases of Trifecta valve failure. We performed a redo aortic valve replacement in five patients and a transcatheter aortic valve replacement in two patients. The SVD rate was 4.8% at 5 years and 6.6% at 7 years. The mean pressure gradient and peak velocity on the first postoperative echocardiogram in patients with SVD were higher than those in patients without SVD. The SVD rates with and without patient-prosthesis mismatch (PPM) were 2.8% and 12.6% at 5 years and 2.8% and 20.0% at 7 years. PPM is a risk factor for SVD. Noncoronary cusp tears were observed in all patients who had undergone redo surgery.

CONCLUSIONS

The most common cause of SVD was noncoronary cusp tear. Patients with PPM are at high risk of developing SVD.

Analysis of incidence and reasons for re-intervention after aortic valve replacement using the Trifecta aortic bioprosthesis

INTRODUCTION

Trifecta bioprosthesis claims favourable haemodynamic performance. However, reports of structural valve deterioration (SVD) raise concerns of its long-term durability. We assessed outcomes with the Trifecta valve over a 10-year period.

METHODS

All patients receiving Trifecta bioprostheses between October 2011 and October 2020 were included. Perioperative and survival characteristics were prospectively collated in an independent database. Re-intervention was recorded as a surrogate for SVD.

RESULTS

944 patients (mean age 72.82 years ± 8.13, 58% male) underwent aortic valve replacement with the Trifecta valve. At 10-years, 1.4% of patients required a redo operation, giving an overall freedom from re-intervention of 98.6%. The mean time to re-intervention was 48.87 months. Survival was 73.58% and 76.92% in patients who did not require re-intervention vs re-intervention group, respectively.

CONCLUSIONS

In a large, single-centre cohort, the Trifecta aortic bioprosthesis had a 1.4% all-cause re-intervention rate at 10-years, with insignificant impact on survival.

Early outcomes of patient-prosthesis mismatch following aortic valve replacement

INTRODUCTION

Patient-prosthesis mismatch (PPM) has been associated with numerous short- and long-term adverse events. This study aimed to evaluate the effect of PPM on early postoperative results after aortic valve replacement (AVR) in daily practice.

METHODS

In this single-centre retrospective study, 150 non-consecutive patients from March 2019 to January 2020 with clinically indicated AVR with/without concomitant surgery were analysed. The study protocol included operative mortality, complication rate, and pre- and postoperative echocardiographic data. PPM was considered severe with indexed effective orifice area at <0.65 cm²/m², moderate at 0.65-0.85 cm²/m² and none at >0.85 cm²/m².

RESULTS

Moderate PPM was observed in 16 patients (10.6%). No patient had severe PPM. PPM was not related to early mortality (r = 0.40, p = 0.630), intra- (r = -0.076, p = 0.352) and postoperative (r = -0.0134, p = 0.102) events.

CONCLUSION

In this study, moderate PPM was a frequent finding after AVR, whereas severe PPM was not observed. PPM did not affect the early results after AVR. A long-term follow-up study in a large patient population is required to assess the actual influence of residual PPM.

The benefit of fibrosa layer stripping technique during minimally invasive aortic valve replacement for calcified aortic valve stenosis-A randomized controlled trial

BACKGROUND

Fibrosa layer stripping (FLS) technique is a new approach to remove the calcified aortic valve. In this study, we aimed to assess the effectiveness of the FLS technique by comparing it with the conventional technique in minimally invasive aortic valve replacement (MIAVR).

METHODS

A prospective, single-center, randomized controlled trial was conducted at Beijing Anzhen Hospital. Seventy patients diagnosed with severe calcific aortic stenosis were randomly assigned to undergo FLS (n = 35) or conventional (n = 35) technique to debride calcified aortic valve. Preoperative profile, procedural parameters, and postoperative outcomes were analyzed.

RESULTS

No significant difference was observed in the preoperative profile between the two groups. Compared with the conventional technique, the FLS technique had a significantly higher indexed effective orifice area and lower mean gradient. Moreover, the FLS technique was associated with significantly reduced aortic cross-clamp time (41 [38-44] vs. 56 [51-60] min, p < .001), cardiopulmonary bypass (CPB) time (63 [56-69] vs. 81 [75-84] min, p < .001), and operative time (148 [141-156] vs. 173 [169-180] min, p < .001). Lastly, the length of intensive care unit stay (1.2 ± 0.4 vs. 1.5 ± 0.8 days, p = .041) and hospital stay (5.3 ± 0.6 vs. 6.0 ± 1.4 days, p = .020) was significantly reduced in the FLS group compared with those in the conventional group.

CONCLUSIONS

FLS technique is effective in removing calcified tissue during MIAVR and is associated with shorter cross-clamp time and CPB time, and better hemodynamic performance than the conventional technique.

Sizing Strategy and Implant Considerations for the Avalus Valve

Hemodynamic performance of the Avalus valve through 3 years after implant is comparable to that of contemporary surgical bioprostheses. Many variables affect hemodynamic outcomes, including surgical technique. This article describes our experience with the Avalus bioprosthesis and strategies to achieve optimal hemodynamic performance.

Computed Tomography-based evaluation of porcine cardiac dimensions to assist in pre-study planning and optimized model selection for pre-clinical research

The pig (Sus Scrofa Domestica) is an accepted model for preclinical evaluation of prosthetic heart valves and trans-catheter implantation techniques. Understanding porcine cardiac dimensions through three-dimensional computed tomography (CT), increases preclinical study success, leading to higher cost efficiency and to the observance of the obligation to the 3 R principles. Cardiac CT images of twenty-four Swiss large white pigs were segmented; aortic root, mitral valve, pulmonary trunk, tricuspid valve, as well as the aorto-mitral angle and left atrial height were analyzed. Correlation coefficient (r) was calculated in relation to body weight. In Swiss large white pigs, valvular dimensions, length of the pulmonary artery and ascending aorta as well as left atrial height correlate with body weight. Coronary ostia heights and aorto-mitral angle size can be neglected in animal size selection; no changes were found for either of the two parameters with increasing body weight.

Effect of the valve design on pressure drop, pressure recovery, and spatial positioning of vena contracta

BACKGROUND

Bioprostheses are complex structures and yield a very complex fluid dynamics. Hence, it can be hypothesized that prosthesis structural characteristics affect the position of the vena contracta and, consequently, influences the pattern and the extent of pressure recovery downstream from the vena contracta.

MATERIALS AND METHODS

The study was performed on pericardial aortic prostheses, specifically Crown 21 and 23 (LivaNova PLC, UK), Trifecta 19 and 21 (Edwards Lifescience, USA), and Magna 19 and 21(Abbott, USA), tested in an "ad hoc" devised steady flow loop circuit at four flow rates (10, 15, 20, and 25 L/min). Fluid dynamic quantities were obtained by direct pressure measurement and Doppler interrogation.

RESULTS

Pressure drop at 25 L/min flow rate was 26.5 ± 0.3 mm Hg and 14.9 ± 0.1 mm Hg for the Trifecta 19 and 21, 37.1 ± 1.0 mm Hg and 27.3 ± 0.4 mm Hg for the Magna 19 and 21, and 36.6 ± 1.0 mm Hg and 22.7 ± 0.1 mm Hg for Crown 21 and 23, respectively. The vena contracta was shorter for Trifecta compared with the Magna and the Crown in which it developed further downstream and as far as 1 cm from the valve leaflets fringes. The pressure recovery was 54% ± 1% for Trifecta 21, 39% ± 1% for Magna 21, and 41% ± 2% for Crown 23 with different patterns.

CONCLUSION

The design of bioprosthesis affects pressure recovery and the position of the vena contracta. The different patterns of pressure recovery might have clinical impact.

Mid-term single-center outcomes of BioIntegral compared to Freestyle aortic conduit implantation

BACKGROUND

Full aortic root replacement with biological conduit has limited options. This non-randomized cohort study aims to compare mid-term clinical and hemodynamic results of the BioIntegral (BI) composite biological versus the stentless Freestyle (FS) conduits in patients undergoing full aortic root replacement.

METHODS

From February 2013 to July 2017, 265 patients underwent aortic root replacement at a single institution (202 BI, 65 FS). Preoperative, intraoperative and postoperative parameters, complications including stroke, myocardial infarction (MI), endocarditis and reoperation were studied. Hemodynamic performance of both conduits was analyzed by echocardiography. Target endpoints were 30-day mortality, two-year survival, two-year freedom from major adverse valve-related and cardiovascular events.

RESULTS

Wider BI conduits were used (BI 27±2 vs. FS 25±2 mm, P<0.0001). The BI group had shorter cardiopulmonary bypass (BI 165±67 vs. FS 200±78 min, P<0.0001) and cross-clamp (BI 102±36 vs. FS 122±40 min, P=0.001) times. Thirty-day mortality was similar in both groups. There were fewer conduit-related reoperations in the BI group (BI 0% vs. FS 3%, P=0.012) but higher postoperative atrial fibrillation (BI 31% vs. FS 17%, P=0.025). No significant differences were observed for stroke (BI 5% vs. FS 10%, P=0.947), MI (BI 3% vs. FS 4%, P=0.583), or infective endocarditis (BI 0% vs. FS 2%, P=0.077). No significant hemodynamic differences were evident on follow-up echocardiography while an improved overall survival trend was seen in the BI group (P=0.062).

CONCLUSIONS

FS and BI provide comparable clinical mid-term results and hemodynamic parameters. Simplified implantation technique providing shorter cardiopulmonary bypass and operation times are advantageous for BI.

Late clinical outcomes of aortic valve replacement with Carpentier-Edwards pericardial valves

Background

The present study aimed to compare the long-term clinical and hemodynamic outcomes of aortic valve replacement using Carpentier-Edwards Perimount (Perimount) or Perimount Magna (Magna) valves.

Methods

We enrolled 430 patients who underwent aortic valve replacements with Perimount (n=58) or Magna (n=372) valves [1998-2013]. Multivariable and inverse probability of treatment weight (IPTW) analyses were performed.

Results

Before IPTW analysis, the overall 8-year survival rate differed significantly between the groups [Perimount 90%±4% vs. Magna 76%±4%; P=0.02; hazard ratio (HR): 0.37 for the Perimount group; 95% confidence interval (CI): 0.17-0.83]. Multivariable analysis of the overall survival identified Perimount valve use as a protective factor (P=0.009; HR: 0.32; 95% CI: 0.14-0.75). Independent risk factors of overall survival were older age, male sex, higher preoperative left ventricular mass index, lower ejection fraction, lower aortic valve pressure gradient, and lower haemoglobin. After applying IPTW, overall survival was again found to be significantly longer in the Perimount group (P=0.04; HR: 0.43; 95% CI: 0.20-0.93). Event-free survival was also better in the Perimount group (P=0.006; HR: 0.38; 95% CI: 0.19-0.75). However, the Magna group had significantly lower aortic valve pressure gradients at one year and five years postoperative.

Conclusions

Although Magna use led to decreased aortic valve pressure gradients at follow-up, overall and event-free survival rates were significantly better with use of the Perimount valve. Additional and larger studies are needed to confirm these results.

Early First-Generation Trifecta Valve Failure: A Case Series and a Review of the Literature

BACKGROUND

The Trifecta valve (Abbott, St Paul, MN) has excellent hemodynamic performance with acceptable rates of freedom from structural valve degeneration. However, some recent studies have reported early Trifecta valve failure. Here, we report a case series of seven Trifecta valve failures with a review of the literature.

METHODS

Of 107 implantations of Trifecta bioprostheses between 2012 and 2014, we encountered seven Trifecta valve failures (6.5%). Failure of a 19-mm Trifecta valve occurred in 1 patient, failure of a 21-mm Trifecta valve occurred in 5 patients, and failure of a 23-mm Trifecta valve occurred in 1 patient. The mean duration of valve durability was 51 ± 16 months. The mean effective orifice area index on the first echocardiogram after Trifecta valve implantation was 0.96 ± 0.26. The mode of presentation was prosthetic valve stenosis in 3 patients and severe aortic regurgitation in 4 patients.

RESULTS

Six patients underwent redo surgical aortic valve replacement. The common pathologic findings were circumferential pannus formation with noncoronary cusp tear and leaflet calcification. The rates of preoperative end-renal stage disease and postoperative prosthesis-patient mismatch were higher in patients with Trifecta valve failure. The incidence of early Trifecta valve failure was 3.1% at 48 months and 13.1% at 72 months.

CONCLUSIONS

In our experience, early Trifecta valve failure was caused by cusp tears or leaflet calcification. Patients with end-renal stage disease and prosthesis-patient mismatch should be closely followed. Some patients with cusp tears may require urgent surgery.

Patient-prosthesis mismatch following aortic valve replacement

Patient-prosthesis mismatch (PPM) occurs when an implanted prosthetic valve is too small for the patient; severe PPM is defined as an indexed effective orifice area (iEOA) <0.65 cm2/m2 following aortic valve replacement (AVR). This review examines articles from the past 10 years addressing the prevalence, outcomes and options for prevention and treatment of PPM after AVR. Prevalence of PPM ranges from 8% to almost 80% in individual studies. PPM is thought to have an impact on mortality, mainly in patients with severe PPM, although severe PPM accounts for only 10–15% of cases. Outcomes of patients with moderate PPM are not significantly different to those without PPM. PPM is associated with higher rates of perioperative stroke and renal failure and lack of left ventricular mass regression. Predictors include female sex, older age, hypertension, diabetes, renal failure and higher surgical risk score. PPM may be a marker of comorbidity rather than a risk factor for adverse outcomes. PPM should be suspected in patients with persistent cardiac symptoms after AVR when there is high prosthetic valve velocity or gradient and a small calculated effective orifice area. After exclusion of other causes of increased transvalvular gradient, re-intervention may be considered if symptoms persist and are unresponsive to medical therapy. However, this decision needs to consider the available options to relieve PPM and whether expected benefits justify the risk of intervention. The only effective intervention is redo surgery with implantation of a larger valve and/or annular enlargement. Therefore, focus needs to be on prevention.