A Compact Mock Circulation Loop for the In Vitro Testing of Cardiovascular Devices

Abstract

In vitro cardiovascular device performance evaluation in a mock circulation loop (MCL) is a necessary step prior to in vivo testing. A MCL that accurately represents the physiology of the cardiovascular system accelerates the assessment of the device's ability to treat pathological conditions. To serve this purpose, a compact MCL measuring 600 × 600 × 600 mm (L × W × H) was constructed in conjunction with a computer mathematical simulation. This approach allowed the effective selection of physical loop characteristics, such as pneumatic drive parameters, to create pressure and flow, and pipe dimensions to replicate the resistance, compliance, and fluid inertia of the native cardiovascular system. The resulting five-element MCL reproduced the physiological hemodynamics of a healthy and failing heart by altering ventricle contractility, vascular resistance/compliance, heart rate, and vascular volume. The effects of interpatient anatomical variability, such as septal defects and valvular disease, were also assessed. Cardiovascular hemodynamic pressures (arterial, venous, atrial, ventricular), flows (systemic, bronchial, pulmonary), and volumes (ventricular, stroke) were analyzed in real time. The objective of this study is to describe the developmental stages of the compact MCL and demonstrate its value as a research tool for the accelerated development of cardiovascular devices.

A Physical Model of the Human Circulatory System for the Modeling, Control and Diagnostic of Cardiac Support Processes

“…The system will contain left and right atriums models in the form of tanks with adequate capacity and input and output connectors. In the most of hydraulic models of the heart, atrial contraction is not simulated [3,4]. Due to the small medical significance of this phenomenon and the high cost of its representation in proposed system, this contraction will not be realized.…”

Automatic control of dual left ventricular assist devices as a biventricular assist device

“…It could be argued that the results in this thesis would be more clinically relevant if the experiments used a clinically available centrifugal pump. However, [74] the control objectives that are described in the next chapter are almost all pump-independent. Giridharan and Skliar established this by testing their control system using both axial and centrifugal pumps [106].…”

“…The MCL designed and constructed by Timms and colleagues [74], [131] MCLs used for control system evaluation are left-sided only loops which makes them unsuitable for this thesis.…”

“…A physical five element Windkessel mock circulation loop (MCL) including systemic and pulmonary circulations was used for this study [74], [75]. In brief, ventricular systole was controlled through a series of electropneumatic regulators (ITV2030-012BS5, SMC Pneumatics, Tokyo, Japan) and 3/2 way solenoid valves (VT325-035DLS, SMC Pneumatics, Tokyo, Japan) to provide passively filled heart chambers and variable contractility, heart rate and systolic time.…”

“…An atrial kick was also included to assist in shifting fluid across the atrioventricular valves. Atrial contraction was implemented in a manner similar to the ventricles, as described in [74]. The contractility (as represented by the maximum current sent to the electropneumatic regulators during systole) of the atria was varied manually until the atrial and ventricular pressures equalized at the end of ventricular diastole.…”