Evaluation of influence of LVAD assistance on haemodynamic and ventricular energetics in closed-loop mock circulatory system.

The choice of control strategy of a Left Ventricle Assist Device in heart recovery is an open problem. It affects circulatory parameters, myocardial perfusion and energetic variables, directly related to oxygen consumption in both ventricles. The experiments were performed by a computer controlled closed loop mock circulatory system, in known and constant pathological condition, connected to a pneumatic LVAD. The assistance was realized by changing artificial left ventricular systole duration and its relation to the QRS complex of ECG signal. The data were analyzed as a function of haemodynamic parameters as well as energetic variables (external work EW, oxygen consumption V0(2), cardiac mechanical efficiency CME). The results have shown: 1) assistance effect, besides driving pressure of the artificial ventricle, depends on its systole beginning and duration and on the value of peripheral resistance; 2) left heart assistance influences right ventricular parameters in limited way; it increases right atrial pressure and decreases arterial pulmonary pressure and oxygen consumption.