The flow patterns of a prosthetic heart valve in the aortic or mitral position can change according to its type and orientation. This work describes the use of 2D particle image velocimetry (PIV) applied to the in vitro flow fields characterization inside the upper part of a left ventricular model at various heart rates and as a function of two orientations of stented tricuspid mitral bioprostheses. In the ventricular model, each mitral bioprosthesis (27 and 31 mm diameter) was installed in two orientations, rotated by 180°, while the aortic bileaflet mechanical valve (27 mm diameter) remained in a fixed orientation. The results (N = 50) showed changes in the intraventricular flow fields according to the mitral bioprostheses positioning. Also, changes in the aortic upstream velocity profiles were noticed as a function of mitral orientations.

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ObjectiveThis work describes the experimental validation of a cardiac simulator for three heart rates (60, 80 and 100 beats per minute), under physiological conditions, as a suitable environment for prosthetic heart valves testing in the mitral or aortic position.MethodsIn the experiment, an aortic bileaflet mechanical valve and a mitral bioprosthesis were employed in the left ventricular model. A test fluid of 47.6% by volume of glycerin solution in water at 36.5ºC was used as blood analogue fluid. A supervisory control and data acquisition system implemented previously in LabVIEW was applied to induce the ventricular operation and to acquire the ventricular signals. The parameters of the left ventricular model operation were based on in vivo and in vitro data. The waves of ventricular and systemic pressures, aortic flow, stroke volume, among others, were acquired while manual adjustments in the arterial impedance model were also established.ResultsThe acquired waves showed good results concerning some in vivo data and requirements from the ISO 5840 standard.ConclusionThe experimental validation was performed, allowing, in future studies, characterizing the hydrodynamic performance of prosthetic heart valves.

ObjectiveTo complement the ISO 5840 standards concerning the duration of left ventricular systole and diastole as a function of changes in heart rates according to in vivo studies from the physiologic literature review.MethodsThe systolic and diastolic durations from three in vivo studies were compared with the durations of systole proposed by the ISO 5840:2010 and ISO 5840-2:2015 for hydrodynamic performance assessment of prosthetic heart valves.ResultsBased on the in vivo studies analyzed, the systolic durations proposed by the ISO 5840 standard seemed consistent for 45 and 120 beats per minute (bpm), and showed diverse results for the 70 bpm condition.ConclusionInformation on the realistic validation of the operation of left ventricular models for different heart rates were obtained.

IntroductionIn vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench.Objective To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. MethodsTo provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. ) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. ResultsIt was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. Conclusions Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.