Fluid Dynamic Assessment of Three Polymeric Heart Valves Using Particle Image Velocimetry

Abstract

Polymeric heart valves have the potential to reduce thrombogenic complications associated with current mechanical valves and overcome fatigue-related problems experienced by bioprosthetic valves. In this paper we characterize the in vitro velocity and Reynolds Shear Stress (RSS) fields inside and downstream of three different prototype trileaflet polymeric heart valves. The fluid dynamic differences are then correlated with variations in valve design parameters. The three valves differ in leaflet thickness, ranging from 80 to 120 mum, and commisural design, either closed, opened, or semi-opened. The valves were subjected to aortic flow conditions and the velocity measured using three-dimensional stereo Particle Image Velocimetry. The peak forward flow phase in the three valves was characterized by a strong central orifice jet of approximately 2 m/s with a flat profile along the trailing edge of the leaflets. Leakage jets, with principle RSS magnitudes exceeding 4,500 dyn/cm(2), were observed in all valves with larger leaflet thicknesses and also corresponded to larger leakage volumes. Additional leakage jets were observed at the commissural region of valves with the open and the semi-open commissural designs. The results of the present study indicate that commissural design and leaflet thickness influence valve fluid dynamics and thus the thrombogenic potential of trileaflet polymeric valves.

In Vitro Characterization of Bicuspid Aortic Valve Hemodynamics Using Particle Image Velocimetry

“…3), to simulate pulsatile physiological flow and pressure conditions in an in vitro setup. 11,22,[40][41][42] Compliance and resistance elements were adjusted to achieve desired flow and pressure conditions. The cardiac output, ventricular pressure and aortic pressure were measured at 500 Hz using a custom LabView program for 15 cycles, to obtain statistically converged ensemble averaged flow and pressure curves.…”

“…11,22,29 The present PIV system consisted of a pair of pulsed Nd:YAG lasers (ESI Inc., Portland, OR; 17 mJ energy, 532 nm wavelength, 9 ns pulse duration) and a combination of spherical and cylindrical lenses to create a laser sheet. The flow was seeded with fluorescent polymethyl methacrylate (PMMA) particles (Dantec Dynamics, Denmark, D = 1-20 lm, labeled with Rhodium-B dye, emission at 580 nm).…”

Hemodynamics of the Hepatic Venous Three-Vessel Confluences Using Particle Image Velocimetry

“…The flows also do not likely correspond to significant blood damage conditions due to the very short exposure times. 39,78 Paul et al 53 reported that for exposure times ranging between 25 and 1250 ms, for a minimum shear stress of 300 dyne/cm 2 , the maximum hemolysis, characterized by the hemolysis index (HI), reaches 3.5%. Since the median exposure time calculated from the present PIV measurements is only 3.5 ms, it is unlikely that blood damage is significant for either anatomical junction.…”

Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies

“…7). 17,26,[45][46][47]64,66,68,76,77,88,91,97,98,103,130,138 However, PIV methods were mainly two dimensional until Bru¨cker introduced Stereo-PIV based on the use of two digital cameras and PIV algorithms to study the flow past artificial heart valves. 21 The testing requirements for performing stereo-PIV for characterizing the flow through mechanical heart valves has been well described by Morbiducci et al 115 Another breakthrough in PIV was the development of defocusing digital particle image velocimetry (D-DPIV).…”