Effect of the undisturbed pericardium on left ventricular size and performance during acute volume loading

Studies in instrumental dogs have suggested that the pericardium alters left ventricular diastolic pressure-volume relations and thus may influence systolic performance. However, the instrumentation used in these studies disrupts the pericardium and may have influenced the results. We therefore studied five conscious dogs by methods not traumatic to the pericardium, before and after pericardiectomy. Although heart rate and left ventricular systolic and end-diastolic pressures were not different before or after pericardiectomy, either at rest or during volume loading, end-diastolic volume measured by biplane two-dimensional echocardiography increased post pericardiectomy at rest from 38 +/- 4 (SE) to 61 +/- 4 ml (p less than 0.05) and during volume loading from 68 +/- 5 to 79 +/- 5 ml (p less than 0.005). After pericardiectomy, ejection fraction was unchanged, but the peak value of the first derivative of left ventricular systolic pressure (dP/dt) increased significantly at rest from 17 +/- 2 to 26 +/- 4.0 x 10(2) mm Hg/sec. We conclude that pericardiectomy shifts the left ventricular end-diastolic pressure-volume curve to the right and increases the systolic isovolumic index of dP/dt in the basal state.