Stented versus Stentless Aortic Valve Replacement in Patients with Small Aortic Root

Objective

The aim of the study was to compare hemodynamic and perioperative outcomes of stented against stentless aortic valve replacement in patients with small aortic root (21 mm or less).

Methods

A comprehensive search was undertaken among the four major databases (PubMed, Embase, Scopus, and Ovid) to identify all randomized and nonrandomized controlled trials comparing stentless to stented bioprosthetic valves in small aortic root patients. Odds ratios, weighted mean differences, or standardized mean differences and their 95% confidence intervals were analyzed.

Results

A total of seven studies with a total of 965 patients fulfilled the inclusion criteria. There was no significant difference in preoperative baselines including mean age between both groups ( P = 0.08), peak aortic valve gradient ( P = 0.06), and effective orifice area ( P = 0.28), whereas higher mean aortic valve gradient in the stented group ( P = 0.007). No difference in cardiopulmonary bypass time ( P = 0.74), aortic cross-clamp times ( P = 0.88), intensive care unit stay ( P = 0.13), and stroke rate ( P = 0.56) were noted. However, stented group of patients showed higher rate of patient prosthesis mismatch ( P = 0.0001) and longer total hospital stay ( P = 0.002). Postoperatively, stentless group showed lower peak and mean aortic valve gradient ( P = 0.003 and P = 0.008, respectively) with a better effective orifice area ( P < 0.00001) at 6 months of follow-up. Mortality rates while in-hospital and at 1 year were similar in both groups ( P = 0.94 and P = 0.86, respectively).

Conclusions

Stentless aortic valves offer superior short-term hemodynamic outcomes in patients with small aortic root when compared with stented aortic valves. Although both groups have similar perioperative complications rates, stentless valves bring about a shorter hospital stay. A further large multicenter randomized controlled trial should address the longer-term benefit of stentless aortic valve over stented valve.

Hemodynamic and clinical performance of Solo stentless bioprosthetic aortic valves

OBJECTIVE

To report the hemodynamic profile and short- and medium-term outcomes of Freedom Solo and Solo Smart stentless aortic valves implanted at our center.

METHODS

Between 2009 and 2015, all patients undergoing aortic valve replacement using Solo stentless valves at our center were enrolled. Clinical and echocardiographic follow-up was carried out six months postoperatively. Survival and major events, including structural valve deterioration and non-structural valve dysfunction, endocarditis, reoperation and stroke, were assessed through medical records or telephone interview with the referring cardiologist up to November 2015 (mean and maximum follow-up 39±22 and 78 months, respectively).

RESULTS

Patients' (n=345) mean age was 72±8 years, 52% were female and median euroSCORE II was 2.7 (1.5-4.7). There was no intraoperative mortality and in-hospital mortality was 2.6%. Postoperatively, mean transvalvular gradient was 11.9±4.5 mmHg and effective orifice area was 1.9±0.5 cm². Patient-prosthesis mismatch occurred in 14% but was severe in only one patient. Cumulative survival at six years was 72%. Six patients were reoperated: three due to endocarditis, two for structural prosthesis deterioration and one because of periprosthetic fistula. Five patients suffered stroke, three had medically-treated endocarditis and one had structural valve deterioration but was not considered suitable for reoperation. None of the remainder had structural valve deterioration or non-structural valve dysfunction.

CONCLUSIONS

Solo stentless aortic valves are safe to implant, with promising clinical outcomes in short- and medium-term assessment. Moreover, they show an excellent hemodynamic performance: low transvalvular gradients, large effective orifice areas and low incidence of patient-prosthesis mismatch.

Early and mid-term haemodynamic performance and clinical outcomes of St. Jude Medical Trifecta™ valve

Background

New models of aortic bioprostheses have proven excellent early haemodynamic profile, but their mid and long-term performance warrants further systematic assessment. The aim of this study is to report clinical and haemodynamic performance of St. Jude Medical Trifecta bioprosthesis during 5 years of implantation.

Methods

We performed a single centre, retrospective, observational and descriptive study including all 556 individuals who underwent aortic valve replacement (AVR) with the Trifecta bioprosthesis (between July of 2011 and June of 2016). Survival and re-intervention were censored in February 2017. Postoperative ambulatory echocardiographic data was available for 490 patients. A complete clinical follow-up was available in 463 individuals (mean follow-up time, 27±17 months).

Results

In our sample the mean age was 73±9 years, 57.6% were male and median European System for Cardiac Operative Risk Evaluation (EuroSCORE) II was 2.9 (interquartile range, 1.6-5.8). There were 301 (54.1%) combined procedures, mostly coronary artery bypass grafting in 170 (30.6%). Overall 30-days mortality was 5.4% (n=30) and cumulative survival at 5-years was 72.3%. There were 23 (4.3%) permanent pacemaker implantations. During follow-up, 5 (0.9%) patients presented non-structural valve dysfunction (NSVD) and 4 (0.8%) underwent reoperation due to prosthesis endocarditis. At the first ambulatory evaluation transvalvular mean gradient and effective orifice area (EOA) were 10.9±4.1 mmHg and 2.0±0.5 cm², respectively. Severe patient-prosthesis mismatch (PPM) was observed in 5 (1.1%) individuals and moderate in 52 (11.3%).

Conclusions

In a "real-world" clinical setting, our findings support the good overall mid-term haemodynamic and safety profile of the Trifecta bioprosthesis.

Current indications for stentless aortic bioprostheses

The best aortic prostheses have been debated for decades. The introduction of stentless aortic bioprostheses was aimed at improving hemodynamics and potentially the durability of aortic bioprostheses. Despite the good short- and long-term outcomes after implantation of stentless aortic bioprostheses, their use remains limited owing to the technically demanding implantation techniques. Nevertheless, stentless aortic bioprostheses might be of special benefit in certain indications, where they could be a valuable addition to the surgical armamentarium.

Biomechanical Behavior of Bioprosthetic Heart Valve Heterograft Tissues: Characterization, Simulation, and Performance

The use of replacement heart valves continues to grow due to the increased prevalence of valvular heart disease resulting from an ageing population. Since bioprosthetic heart valves (BHVs) continue to be the preferred replacement valve, there continues to be a strong need to develop better and more reliable BHVs through and improved the general understanding of BHV failure mechanisms. The major technological hurdle for the lifespan of the BHV implant continues to be the durability of the constituent leaflet biomaterials, which if improved can lead to substantial clinical impact. In order to develop improved solutions for BHV biomaterials, it is critical to have a better understanding of the inherent biomechanical behaviors of the leaflet biomaterials, including chemical treatment technologies, the impact of repetitive mechanical loading, and the inherent failure modes. This review seeks to provide a comprehensive overview of these issues, with a focus on developing insight on the mechanisms of BHV function and failure. Additionally, this review provides a detailed summary of the computational biomechanical simulations that have been used to inform and develop a higher level of understanding of BHV tissues and their failure modes. Collectively, this information should serve as a tool not only to infer reliable and dependable prosthesis function, but also to instigate and facilitate the design of future bioprosthetic valves and clinically impact cardiology.

North American trial results at 1 year with the Sorin Freedom SOLO pericardial aortic valve

OBJECTIVES

A North American prospective, 15-centre Food and Drug Administration (FDA) valve trial was designed to assess the safety and effectiveness of the Freedom SOLO stentless pericardial aortic valve in the treatment of surgical aortic valve disease.

METHODS

Beginning in 2010, 251 patients (mean: 74.7 ± 7.5 years), were recruited in the Freedom SOLO aortic valve trial. One hundred eighty-nine patients have been followed for at least 1 year and are the basis for this review. Preoperatively, 54% of patients had NYHA functional class III or IV symptoms, and the majority of patients had a normal ejection fraction (EF) (median EF = 61%). Concomitant procedures were performed in 61.9% of patients, with coronary artery bypass grafting (CABG) (48.7%) being the most common followed by a MAZE procedure (13.7%). Reoperations were performed in 8.5% of patients in the study.

RESULTS

The entire cohort of 251 patients enrolled had 7 deaths prior to 30 days, 2 of which were valve-related (aspiration pneumonia and sudden death) and 5 were not valve-related. There were 11 deaths after 30 days, 1 valve-related (unknown cardiac death) and 10 not valve-related. Five valves were explanted, 3 early (endocarditis, acute insufficiency and possible root dissection) and 2 late (endocarditis). Thirty-day adverse events include arrhythmias requiring permanent pacemaker (4.2%), thromboembolic events (3.7%) and thrombocytopenia (7.4%). One-year follow-up of all 189 patients demonstrated mean gradients for valve sizes 19, 21, 23, 25 and 27 mm of 11.7, 7.8, 6.3, 4.6 and 5.0 mmHg, respectively. Effective orifice areas for the same valve sizes were 1.2, 1.3, 1.6, 1.8 and 1.9 cm(2), respectively. Ninety-six percent of patients (181/189) were in NYHA class I or II at the 1-year follow-up.

CONCLUSIONS

The Freedom SOLO stentless pericardial aortic valve demonstrated excellent haemodynamics and a good safety profile out to the 1 year of follow-up.

Blood flow characteristics in the ascending aorta after aortic valve replacement--a pilot study using 4D-flow MRI

BACKGROUND

Aortic remodeling after aortic valve replacement (AVR) might be influenced by the postoperative blood flow pattern in the ascending aorta. This pilot study used flow-sensitive four-dimensional magnetic resonance imaging (4D-flow) to describe ascending aortic flow characteristics after various types of AVR.

METHODS

4D-flow was acquired in 38 AVR patients (n=9 mechanical, n=8 stentless bioprosthesis, n=14 stented bioprosthesis, n=7 autograft) and 9 healthy controls. Analysis included grading of vortex and helix flow (0-3 point scale), assessment of systolic flow eccentricity (1-3 point scale), and quantification of the segmental distribution of peak systolic wall shear stress (WSS(peak)) in the ascending aorta.

RESULTS

Compared to controls, mechanical prostheses showed the most distinct vorticity (2.7±0.5 vs. 0.7±0.7; p<0.001), while stented bioprostheses exhibited most distinct helicity (2.6±0.7 vs. 1.6±0.5; p=0.002). Instead of a physiologic central flow, all stented, stentless and mechanical prostheses showed eccentric flow jets mainly directed towards the right-anterior aortic wall. Stented and stentless prostheses showed an asymmetric distribution of WSS(peak) along the aortic circumference, with significantly increased local WSS(peak) where the flow jet impinged on the aortic wall. Local WSS(peak) was higher in stented (1.4±0.7 N/m(2)) and stentless (1.3±0.7 N/m(2)) compared to autografts (0.6±0.2 N/m(2); p=0.005 and p=0.008) and controls (0.7±0.1 N/m(2); p=0.017 and p=0.027). Autografts exhibited lower absolute WSS(peak) than controls (0.4±0.1 N/m(2) vs. 0.7±0.2 N/m(2); p=0.003).

CONCLUSIONS

Flow characteristics in the ascending aorta after AVR are different from native aortic valves and differ between various types of AVR.

Freestyle root replacement for complex destructive aortic valve endocarditis

OBJECTIVES

In destructive aortic valve endocarditis with abscess formation in the root, homografts are used more often than xenografts. Because we had reliable perioperative results with Freestyle (Medtronic Inc, Minneapolis, Minn) xenograft root replacement in these complex patients, we analyzed the long-term outcome in this high-risk indication.

METHODS

Of 126 consecutive patients with aortic valve endocarditis treated by surgery from 1997 to 2012, 32 (25.4%) received a Freestyle aortic root replacement for severe, destructive valve endocarditis and were studied retrospectively with approval of the local ethical committee. Perioperative complications, recurrence of endocarditis, and long-term morbidity and mortality were analyzed. The follow-up period was 3 months to 11.5 years.

RESULTS

Indication for surgery was native (n = 9) and prosthetic valve endocarditis (n = 23). In 18 patients, concomitant procedures were performed: coronary bypass (n = 9), additional valve surgery (n = 6), and ascending aortic surgery (n = 7). Thirty-day mortality was 19.4% (n = 6). There were no instances of technical failure requiring modification of the surgical strategy or reoperation for anastomotic bleeding. Actuarial survival at 5 and 10 years was 61.9% and 54.2%, respectively. Freedom from death, reoperation for prostheses dysfunction, and recurrence of endocarditis as the composite end point at 5 and 10 years was 56.3% and 53.1%, respectively.

CONCLUSIONS

The Freestyle root was used successfully with no technical complications in all patients with most severe destructive aortic root endocarditis. In view of this complex patient population, short- and long-term results make this conduit a reliable choice for treatment of this condition.