BIOMECHANICS OF POSITIVE INTRATHORACIC PRESSURE AND ITS EFFECTS ON LEFT VENTRICULAR FILLING IN HEALTHY SUBJECTS

Abstract

This study aims to explore the biomechanics of positive intrathoracic pressure and its effects on left ventricle (LV) filling in healthy subjects. 30 healthy subjects were enlisted to perform a Valsalva maneuver (VM) with a load of 40[Formula: see text]mmHg lasted 10[Formula: see text]s. LV filling parameters were measured by echocardiography at rest and at 10[Formula: see text]s during the VM. Compared with the at rest values, LV early inflow velocity (E) decreased significantly ([Formula: see text]), late inflow velocity (A) decreased insignificantly ([Formula: see text]), while the E/A ratio decreased significantly ([Formula: see text]) after 10[Formula: see text]s of the strain phase of the VM. LV septal early tissue velocity ([Formula: see text]) and lateral early tissue velocity ([Formula: see text]) of the mitral did not change ([Formula: see text]), while the [Formula: see text] ratio and the [Formula: see text] ratio decreased significantly ([Formula: see text] after 10[Formula: see text]s during the VM. Based on these results, biomechanical analysis suggests that the effects of positive intrathoracic pressure on the LV free wall impede LV diastolic motion, which may be one of the factors contributing to a decrease in E and the E/A ratio. Positive intrathoracic pressure also increases the flow resistance of the LV and pulmonary vasculature, which may contribute to a decrease in E, the [Formula: see text] ratio, and the [Formula: see text] ratio.