[The physiological role of the pericardium: studies based on right heart inflow dynamics in cases of left-sided pericardial defect].

Using pulsed Doppler echocardiography, the effects of postural change on the blood flow pattern in the superior vena cava and in the right ventricular inflow tract were investigated to evaluate the physiological role of the pericardium. Eight cases of left-sided pericardial defect and eight healthy subjects were examined. 1. Suppressed inflow into the right atrium during systole in left-sided pericardial defect was manifested as a reduction of the systolic wave (S) in the superior caval vein and impairment of the systolic shift of the tricuspid annulus. This suppression suggested unsatisfactory volume expansion in the right atrium due to the absence of negative intrapericardial pressure. 2. In left-sided pericardial defect, the right ventricular inflow pattern differed from the normal, most distinctly in the right lateral recumbent position, though the cardiac motion was nearly identical with that of the normal in this position. In this position, the ratio of the peak velocity of presystolic filling to that of rapid filling was increased, and the deceleration half time of rapid filling was prolonged. These findings indicated that the right ventricular rapid filling was retarded, and was compensated by the filling due to atrial contraction. It is assumed that right ventricular filling is influenced by hydrostatic pressure due to changes in posture in the absence of restriction by the pericardium. 3. It is concluded that the pericardium maintains negative intrapericardial pressure, so that each cardiac chamber is uniformly expanded for its filling, and that this function minimizes the influence of posture on cardiac hemodynamics.