Left atrial assist device function at various heart rates using a mock circulation loop

Abstract

We are developing a new left atrial assist device (LAAD) for patients who have heart failure with preserved ejection fraction (HFpEF). This study aimed to assess the hemodynamic effects of the LAAD under both normal heart conditions and various diastolic heart failure (DHF) conditions using a mock circulatory loop. A continuous-flow pump that simulates LAAD, was placed between the left atrial (LA) reservoir and a pneumatic ventricle that simulated a native left ventricle on a pulsatile mock loop. Normal heart (NH) and mild, moderate, and severe DHF conditions were simulated by adjusting the diastolic drive pressures of the pneumatic ventricle. With the LAAD running at 3200 rpm, data were collected at 60, 80, and 120 bpm of the pneumatic ventricle. Cardiac output (CO), mean aortic pressure (AoP), and mean LA pressure (LAP) were compared to evaluate the LAAD performance. With LAAD support, the CO and AoP rose to a sufficient level at all heart rates and DHF conditions (CO; 3.4–3.8 L/min, AoP; 90–105 mm Hg). Each difference in the CO and the AoP among various heart rates was minuscule compared with non-pump support. The LAP decreased from 21–23 to 17–19 mm Hg in all DHF conditions (difference not significant). Furthermore, hemodynamic parameters improved for all DHF conditions, independent of heart rate. The LAAD can provide adequate flow to maintain the circulation status at various heart rates in an in vitro mock circulatory loop.

Left atrial assist device for heart failure with preserved ejection fraction: initial results with torque control mode in diastolic heart failure model

“…Figure 5 shows the wave forms of the flow (CO), AoP, pump speed, and pump power at TC modes 0.9, 1.0, 1.25, and 1.5, respectively, as well as the CO and AoP data without LAAD. As is consistent with our previous report [17], the AoP, CO, and pulsatility decreased with increasing DHF severity without LAAD support (Fig. 5a).…”

“…1d). It is a mixed-flow pump directing blood from the LA to fill the LV from its position at the mitral valve level [15][16][17]. The diameter and height are both 33.5 mm, and the pump utilizes a hydrodynamic bearing for radial support of the rotating assembly and a magnetic, passive bearing to limit its axial movement.…”

Device-Based Solutions to Improve Cardiac Physiology and Hemodynamics in Heart Failure With Preserved Ejection Fraction

“…Although the use of HFrEF MCS devices that support the pumping action of the left ventricle is not recommended in HFpEF, due to reported risks of atrial suction and intraventricular thrombosis ( 86 , 172 , 182 , 185 , 186 , 187 , 188 ), analogous solutions that are specific for HFpEF are currently under development to reduce LAP, enhance LV filling, and restore cardiac output. In this context, a variety of in silico and in vitro studies have been conducted on a number of proposed approaches to investigate their feasibility ( 22 , 175 , 176 , 177 , 178 , 179 ). To date, however, animal experimentation for MCS for HFpEF remains minimal, and no clinical testing has yet been conducted.…”

“…In vitro studies were performed to investigate the hemodynamic effects of this device on an experimental mock circulatory system, configured to simulate various degrees of diastolic dysfunction ( 177 , 178 , 179 ). The performance of the LAAD (ie, left atrium to left ventricle configuration) was compared with that of analogous pumps in 2 other configurations, namely left atrium to aorta and left ventricle to aorta.…”

“…Although the LAAD has been shown to ameliorate the hemodynamics of HFpEF in a variety of studies ( 177 , 178 , 179 , 180 , 181 ), questions remain regarding the site of implantation of the device, as the implications associated with the removal of the mitral valve have yet to be assessed ( 182 ). In addition, although implantation at the supra-valvular level has been suggested to preserve the mitral valve, this configuration has not been studied thoroughly ( 181 ).…”