Violin plot data: A concerto of crucial information on valve thrombogenicity categorized in vitro by valve motion and inferred flow velocity

Abstract

AbstractObjectivesThis in vitro study compares mechanical (MHV) and bioprosthetic (BHV) heart valves for high amplitude short duration regional flow velocities (RFV) near valve closure.BackgroundWe previously tested several clinical and prototype valves and observed RFV at levels which may be related to a dimensionless thrombogenic potential (TP).MethodsA total of four valves were tested in aortic and mitral sites under pulsatile circulation in a pulse duplicator. Valves included both clinical models and experimental prototypes. An optical approach measuring projected dynamic valve area (PDVA) to gauge valve motion was implemented. Pulsatile pressures and flow rates were measured by conventional techniques and a quasi-steady flow tester was used to measure valve leakage. RFV was derived using time-dependent volumetric flow rate/PDVA. Since flow velocity and fluid shear force are related through flow velocity gradient, TPs for valves that achieve near closure during the forward flow deceleration phase were determined as RFVs relative to the control mechanical valve RFV value of −126 m/s.ResultsTP is dimensionless and ranged between −0.45 and +1.0. Negative TPs arise when transient rebound of valve occluders is accompanied by water-hammer phenomena. Positive TPs occur during the decelerating forward flow. Bioprostheses had lowest TP transient of 0.15 with exception of a mock-transcatheter aortic valve (mTAVI) that incorporated by design a trivial perivalvular leak (∼1.35 ml/s). This device demonstrated a remarkably high transient TP of 0.95. The control mechanical valves had the highest TP of 1.0. The study implicates TP transients near mechanical valve closure, and not forward or non-flow phases, as primary to shear induced activation of the coagulation cascade.ConclusionsOur data reveals distinct TP profile differences between valve models. If verifiable, the design of future valves may utilize currently available experimental tools to determine TPs resulting in advanced devices with significantly reduced TP.