Mono and bi-ventricular assistance: their effect on ventricular energetics

When mono- and bi-ventricular mechanical assistance is used for heart recov ery, its control strategy and circulatory variables affect ventricular ener getics (external work-EW, oxygen consumption-VO2, cardiac mechanical effici ency-CME). This study is based on the data obtained in vitro and presents a n analysis of the effects of the mono- and bi-ventricular mechanical assist ance on ventricular energetics. The assistance was conducted on the princip le of counterpulsation with atrio-arterial connection. It includes the foll owing stages. 1) the characterisation of the isolated ventricle model in te rms of EW, VO2 and CME as a function of the filling pressure and peripheral resistance, 2) modelling of left ventricular and pulmonary dysfunction, fo llowed by left ventricular and bi-ventricular assistance. Experimental data enable us to draw the following conclusions: in general, the greatest hemodynamic improvement does not correspond to the highest energetic improvement, LVAD assistance deteriorates left ventricular CME while its effect on right ventricular energetics depends on the value of right ventricular elastance (E-max). Right ventricular CME is deteriorated by BVAD assistance irrespec tive of right E-max, the energetics optimisation in bi-ventricular assistance is closely related to the right E-max, which could probably be a deciding factor in the choic e of the assistance mode.