Optimal timing algorithms of para-aortic counterpulsation device: an animal study.

Para-aortic counterpulsation device (PACD) is a promising therapy for severe heart failure (HF). However, the lack of knowledge about mechanisms has limited its clinical application. The aim of this study was to investigate the optimal timing algorithms. At the following four triggering algorithms, pre-R-wave-deflation and dicrotic notch-inflation (PD), pre-R-wave-deflation and postdicrotic notch-inflation (PP), R-wave-deflation and dicrotic notch-inflation (RD), and R-wave-deflation and postdicrotic notch-inflation (RP), hemodynamic effects of PACD were assessed in vivo. There was more significant promotion of left mean coronary artery flow (Q(LM)), carotid artery flow (Q(CA)), cardiac output (CO), pulmonary artery flow/LA pressure ratio (Q(PA)/LAP), left ventricular myocardial oxygen consumption (LVVO(2)), external LV work (ELVW), and cardiac mechanical efficiency (CME) at RD and RP models than PD and PP models. R-wave-deflation and postdicrotic notch-inflation model provided further benefits. There was significant correlation between LV functional parameters and carotid arterial reflux, but aortic pressure-related parameters. Filling at beginning of LV systolic phase and ejection at the end of isovolumic relaxation phase were the optimal triggering algorithms of PACD. It is suggested that carotid artery reflows and ventricular pressure-related parameters should be used as reference standard to adjust the timing of balloon inflation or deflation.