Hemodynamic Response to Head-up Tilt of Patients Implanted with Biventricular Assist Device

Abstract

Head up tilt (HUT) is commonly used to investigate the ability of the heart to regulate blood pressure. During transition through supine to HUT, blood redistributes from the chest to the lower body below the diaphragm, accompanied by rapid fall in the venous pressures and venous return. Patients suffering from biventricular heart failure and assisted with dual rotary pumps (BiVAD) may undergo right ventricular suction as a result of this transition. In this study, we present a validated lumped parameter model of the cardiovascular system for graded HUT integrated with a BIVAD in order to investigate the hemodynamic response during supine and 70º HUT using two different speed settings for left and right ventricular assist devices (VADs). Operating both VADs at the same speed of 2400 rpm during supine resulted in high left atrial pressure (LAP) subsequently causing congestion. This high LAP was relieved when 70º HUT was simulated; however it resulted in reduced central venous pressure, thereby causing right ventricular suction. On the other hand, operating right ventricle assist device at speed lower than left ventricle assist device avoided events of congestion and suction during supine and 70º HUT.