A New Pulsatile Volumetric Device With Biomorphic Valves for the In Vitro Study of the Cardiovascular System

Abstract

A pulsatile mock loop system was designed and tested. This prototype represents a versatile, adjustable, and controllable experimental apparatus for in vitro studies of devices meant to interface with the human circulatory system. The pumping system consisted of a ventricular chamber featuring two biomorphic silicone valves as the inlet and outlet valves. The chamber volume is forced by a piston pump moved by a computer-controlled, low-inertia motor. Fluid dynamic tests with the device were performed to simulate physiological conditions in terms of cardiac output (mean flow of 5 and 6 L/min, with beat rates from 60 to 80 bpm), of rheological properties of the processed fluid, and of systemic circulation impedance. The pulsating actuator performed a good replication of the physiological ventricular behavior and was able to guarantee easy control of the waveform parameters. Experimental pressure and flow tracings reliably simulated the physiological profiles, and no hemolytic subatmospheric pressures were revealed. The performance of the prototype valves was also studied in terms of dynamic and static backflow, effective orifice area, and pressure loss, resulting in their applicability for this device. Mechanical reliability was also tested over 8 h. The device proved to be a reliable lab apparatus for in vitro tests; the pumping system also represents a first step toward a possible future application of pulsating perfusion in the clinic arena, such as in short-term cardiac assist and pulsatile cardiopulmonary bypass.

In vitro hemodynamics and valve imaging in passive beating hearts

“…Both the PD and the SIS were described in detail in a previous study (Lanzarone et al, 2009). The PD is a volumetric piston pump, which can accurately replicate both systolic and diastolic flow waveforms (Swanson and Clark, 1977;Reul et al, 1981), connected to the left ventricle apex.…”

A Newly Developed Tri-Leaflet Polymeric Heart Valve Prosthesis

“…A pulse duplicator was specifically designed to perform pulsatile flow tests replicating the peripheral compliance and the resistances of the cardiovascular system by a resistance-compliance-resistance (RCR) analogue. 8,9 Each PHV was tested under three different frequencies (45 bpm, 70 bpm, 120 bpm), three backpressures (80 mmHg, 120 mmHg, 160 mmHg) and four mean flow rates (2 L/ min, 3.5 L/min, 5 L/min and 7 L/min), as required by the ISO 5840 Standard for at least 15 cycles.…”

“…2) were manufactured by compression molding from poly(styrene-isoprene/ butadiene-styrene), with 19% polystyrene weight fraction. In vitro tests were performed under both continuous and pulsatile flow on a test bench 8,9 as recommended by ISO 5840 Standard, 10 using distilled water at 25 C. Steady tests were performed at flow rates from 0 to 10 L/min (steps 0.5 L/min). Regurgitation tests were run applying a backpressure in the range of 28-128 mmHg (steps 5 mmHg).…”

Computational Models of Aortic Coarctation in Hypoplastic Left Heart Syndrome: Considerations on Validation of a Detailed 3D model

“…This may be explained by the fact that the main factors responsible for energy dissipation in the investigated anatomy are the aortic coarctation and the shunt. Moreover, needle-pinch valves -additional terms of localized energy dissipations that are thus not very sensitive to viscous effects -were used as the physical components mimicking peripheral vascular R. From a methodological perspective, in vitro alternatives that would better replicate the fact that microvasculature resistance is independent of the flow rate are offered by porous media (39) or bundles of small diameter tubes (1). Using these components, fluid viscosity would play a more important role in determining energy losses, however, this kind of lumped resistance is often cumbersome to construct and more difficult to regulate.…”