Pledget-Armed Sutures Affect the Haemodynamic Performance of Biologic Aortic Valve Substitutes: A Preliminary Experimental and Computational Study

Abstract

Surgical aortic valve replacement is the most common procedure of choice for the treatment of severe aortic stenosis. Bioprosthetic valves are traditionally sewed-in the aortic root by means of pledget-armed sutures during open-heart surgery. Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow rapid implantation, therefore reducing the duration and invasiveness of the intervention. Different effects on the hemodynamics were clinically reported associated with the two technologies. The aim of this study was therefore to investigate whether the differences in hemodynamic performances are an effect of different anchoring systems. Two commercially available bio-prosthetic aortic valves, one sewed-in with pledget-armed sutures and one rapid-deployment, were thus tested in this study by means of a combined approach of experimental and computational tools. In vitro experiments were performed to evaluate the overall hydrodynamic performance under identical standard conditions; computational fluid dynamics analyses were set-up to explore local flow variations due to different design of the anchoring system. The results showed how the performance of cardiac valve substitutes is negatively affected by the presence of pledget-armed sutures. These are causing flow disturbances, which in turn increase the mean pressure gradient and decrease the effective orifice area. The combined approach of experiments and numerical simulations can be effectively used to quantify the detailed relationship between local fluid-dynamics and overall performances associated with different valve technologies.

Outcome of rapid deployment aortic valves: long-term experience after 700 implants

“…As previously reported, we are in favour of direct arterial cannulation also in minimally invasive cases to reduce groin complications (10). The subvalvular stent fixation and the absence of any pledget material might reshape the outflow tract and improve transvalvular hemodynamics, with superior gradients and reduced turbulent flow (11), in comparison to the conventional valve of the same manufacturer (1,12). Fallon and colleagues (13) demonstrated the occurrence of PPM in up to 65% of patients documented in the STS database requiring an isolated AVR, with survival rates being significantly reduced for any degree of PPM (moderate to none: HR, 1.08; 95% CI, 1.05 to 1.12; severe to none: HR, 1.32; 95% CI, 1.25 to 1.39), and 10-year adjusted survival rates of 46%, 43%, and 35% for none, moderate, and severe PPM, respectively (P<0.001).…”

Intermediate-term outcome of 500 consecutive rapid-deployment surgical aortic valve procedures†

“…We previously reported that transvalvular gradients are reduced in this rapid-deployment valve compared to the conventional valve of the same manufacturer [8, 25]. The subvalvular stent-based fixation system may be the reason for a reduced transvalvular gradient as it reshapes the left ventricular outflow tract, avoids pledgets and reduces turbulent flow [26]. Furthermore, this valve system does not allow the use of a smaller valve size than indicated, which might occur in conventional valves, as undersizing may lead to paravalvular leakage.…”

Minimally invasive access type related to outcomes of sutureless and rapid deployment valves

“…Rapid deployment and sutureless aortic valves have the ability to facilitate minimally invasive surgery and are therefore an excellent adjunct to support the required changes in surgical practice [ 2 , 22 , 23 ]. We were able to show improved laminar flow for the Edwards Intuity valve, which opens the left ventricular outflow tract with the stent part of the valve [ 24 ]. This reduces transvalvular gradients and may be a relevant factor contributing to the excellent long-term survival in this patient population [ 3 , 23 , 25 , 26 ].…”