Selective reduction of afterload in right heart assist therapy: a mock loop study

Abstract

The feasibility of RV unloading by a selective decrease in RV afterload was proved in principle. By alternation of the pump speed, gradual reloading in sense of a myocardial training may be achieved. The results will be validated by future animal trials where the relationship between the level of support and pulmonary vascular pressure can be investigated in vivo. Further device design concerning foldable impeller leaflets will be carried out. At a final stage, the crimped version is supposed to reach a size below 1 cm to facilitate minimally invasive insertion.

Hydraulic and Hemodynamic Performance of a Minimally Invasive Intra-arterial Right Ventricular Assist Device

“…Although the presence of bifurcation may alter the downstream flow behavior of the MIRVAD in actual anatomy, it does not significantly change our conclusions in the hydraulic performance and blood damage prediction, which were deduced mainly on the flow path across the pump. The efficacy of the proposed impeller design under a physiological condition with pulsatile flow is reported in a separate paper (12).…”

“…The proposed MIRVAD is an axial-flow pump positioned in the pulmonary artery (PA) after the pulmonary valve to increase pulmonary perfusion (12). Unlike existing RVADs, the MIRVAD is designed to work in series with the weakened RV and fully or partially offload ventricular duty.…”

Mock circulatory loops used for testing cardiac assist devices: A review of computational and experimental models

“…Also Left Ventricular Assist Devices (LVAD) have been used to generate realistic flow conditions controlled by a pneumatic apparatus. 42 By introducing computer-controlled ventricles in the M-MCL, researchers gained the ability to alter cardiac output which allowed simulation of exercising conditions [43][44][45] and pathological conditions such as congestive left heart failure, 39,[46][47][48][49][50][51] right heart failure, 46 valve regurgitation 52,53 and cardiac arrhythmias. 54 Timms et al 55 used a pneumatic ventricle in an M-MCL to simulate normal and heart failure at rest by adjusting mean arterial pressure, heart rate, contractility, SVR, PVR and arterial compliance.…”

Right Ventricular Assessment: Are Regional Longitudinal Measurements of Value?

“…Under normal conditions and physiology, the shape of the RV pressure-volume loop is triangular, or trapezoidal, with nearly absent isovolumic relaxation and contraction periods suggesting that blood flows in and out of the RV continuously as if it were a passive conduit. 5,14,[26][27][28] In the presence of contractile dysfunction, flow through the right heart can still be maintained as long as afterload or pulmonary vascular resistance is low. 8,24 In the presence of cardiopulmonary disease, right ventricular contractility and ventricular interdependence become more important.…”

“…31 In cases of increased RV afterload, or pulmonary hypertension, the RV pressure-volume loop changes from a triangular or trapezoidal shape toward a rectangular shape, with a change in IVS shape and position, requiring greater pressure generation to eject blood forward. 27,28 A leftward shift of the IVS is associated with a reduction in ventricular interdependence and greater hemodynamic dysfunction. The changes in IVS position and geometry alter the direction of myocardial fibers from longitudinal to more transversely directed muscle.…”