Time-Resolved PIV Technique for High Temporal Resolution Measurement of Mechanical Prosthetic Aortic Valve Fluid Dynamics

Abstract

Prosthetic heart valves (PHVs) have been used to replace diseased native valves for more than five decades. Among these, mechanical PHVs are the most frequently implanted. Unfortunately, these devices still do not achieve ideal behavior and lead to many complications, many of which are related to fluid mechanics. The fluid dynamics of mechanical PHVs are particularly complex and the fine-scale characteristics of such flows call for very accurate experimental techniques. Adequate temporal resolution can be reached by applying time-resolved PIV, a high-resolution dynamic technique which is able to capture detailed chronological changes in the velocity field. The aim of this experimental study is to investigate the evolution of the flow field in a detailed time domain of a commercial bileaflet PHV in a mock-loop mimicking unsteady conditions, by means of time-resolved 2D Particle Image Velocimetry (PIV). The investigated flow field corresponded to the region immediately downstream of the valve plane. Spatial resolution as in “standard” PIV analysis of prosthetic valve fluid dynamics was used. The combination of a Nd:YLF high-repetition-rate double-cavity laser with a high frame rate CMOS camera allowed a detailed, highly temporally resolved acquisition (up to 10000 fps depending on the resolution) of the flow downstream of the PHV. Features that were observed include the non-homogeneity and unsteadiness of the phenomenon and the presence of large-scale vortices within the field, especially in the wake of the valve leaflets. Furthermore, we observed that highly temporally cycle-resolved analysis allowed the different behaviors exhibited by the bileaflet valve at closure to be captured in different acquired cardiac cycles. By accurately capturing hemodynamically relevant time scales of motion, time-resolved PIV characterization can realistically be expected to help designers in improving PHV performance and in furnishing comprehensive validation with experimental data on fluid dynamics numeric modelling.

Numerical simulation of the dynamics of a bileaflet prosthetic heart valve using a fluid–structure interaction approach

“…The valve opening motion was notably consistent from cycle to cycle, perhaps due to the stable nature of accelerating flow. On the contrary, leaflet kinematics measurements show that the position of the leaflets exhibits a more pronounced variability from cycle to cycle during the valve closure phase: our experimental results are similar to the highly time resolved PIV measurements by Kaminsky et al (2007a) and Dasi et al (2007).…”

Flow Visualization Through Two Types of Aortic Prosthetic Heart Valves Using Stereoscopic High‐speed Particle Image Velocimetry

“…The measurements were performed to quantify the flow behind the prosthetic aortic heart valve. This novel approach employs the benefits of stereoscopic PIV (5,(8)(9)(10)(11)(12)(13) and the dynamic approach of high-speed (or time-resolved) PIV (14)(15)(16)(17)(18)(19). It enables one to assess all three velocity components with a very high temporal resolution.…”

“…High‐speed PIV is able to generate the fully resolved temporal evolution of the flow downstream the PHV and also to map its complex dynamics characterized by its high nonhomogeneity and unsteadiness. Moreover, time‐resolved PIV permits to monitor the different flow fields in the supravalvular region of the bileaflet model at closure in two simulated cardiac cycles (19). Different closing behavior of the individual leaflets between the two cycles is a phenomenon, which, at conventional sampling rates, cannot always be detected.…”

“…This combination is known as “high‐speed” or “time‐resolved” PIV (14–17). Even higher rates of up to 3000 images per second at a resolution of 1024 × 1024 pixels have nowadays become feasible (18,19). High‐speed PIV is able to generate the fully resolved temporal evolution of the flow downstream the PHV and also to map its complex dynamics characterized by its high nonhomogeneity and unsteadiness.…”

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).…”