Physiological control of a total artificial heart: conductance- and  arterial pressure-based control

Abstract

To obtain a physiological response by a total artificial heart (TAH), while eliminating the hemodynamic abnormalities commonly observed with its use, we proposed the use of a conductance- and arterial pressure-based method (1/R control) to determine TAH cardiac output. In this study, we endeavored to make use of a variable more closely tied to central nervous system (CNS) efferents, systemic conductance, to provide the CNS with more direct control over the output of the TAH. The control equation that calculates the target cardiac output of the TAH was constructed on the basis of measurement of blood pressures and TAH flow. The 1/R control method was tested in TAH-recipient goats with an automatic method by using a microcomputer. In 1/R control animals, the typical TAH pathologies, such as mild arterial hypertension and substantial systemic venous hypertension, did not occur. Cardiac output varied according to daily activity level and exercise in a manner similar to that observed in natural heart goats. These results indicate that we have determined a control method for the TAH that avoids hemodynamic abnormalities exhibited by other TAH control systems and that exhibits physiological responses to exercise and daily activities under the conditions tested. The stability of the control and the complete lack of inappropriate excursions in cardiac output is suggestive of CNS involvement in stabilizing the system.

Concept of left atrial pressure estimation using its pulsatile amplitude in the helical flow total artificial heart

“…However, it was not also easy to control venous pressure [7]. Abe et al [8] proposed the 1/R control method responding to the cardiovascular center and succeeded to control venous pressure [9].…”

Computational modelling and evaluation of cardiovascular response under pulsatile impeller pump support

“…Inevitably those strategies that produce optimal performance against one of the physiological criteria offer degraded performance against others. In the majority of publications to date, the focus has been on a subset of physiological criteria, neglecting the others; for example, cardiac outpute was the major concern in studies [4,[12][13][14][15][16][17]; left atrial pressure was the main target of VAD motion optimization in studies [13,16,[18][19][20]; left ventricular pressure was addressed in [21]; arterial pressure in studies [13,[21][22][23][24]; pressure difference across the VAD in Wu et al [24] and Waters et al [25]; peripheral vascular resistance in Abe et al [12] and Saito et al [16]; heart oxygen consumption in Drzewiecki et al [26]; and venous oxygen saturation in Nakamura et al [27]. Also some VAD characteristic variables such as VAD pump flow [23,28] and VAD pump rotations per minute [10,13] have been included in evaluating the VAD support performance.…”

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

“…Previous investigations into the MS relationship between LVAD and RVAD have assumed that the LVAD should be the master, without providing experimental evidence [175]. In this study, we compared both left/right and right/left MS configurations for our system.…”

“…Previous work by Abe and colleagues investigated control of dual pulsatile pumps for both TAH and BiVAD applications [175], [176]. In both applications, the investigators designated one pump as the master and the other the slave.…”

“…Where CO is the desired cardiac output (L.min For the TAH approach [175], the left pump was set as the master and the right pump the slave. The SV of the right pump was programmed to balance the left and right atrial pressures, using Equation (5.2).…”