Clinical and Laboratory Findings in Patients with Nonobstructive Intraventricular Pressure Differences

Clinical and laboratory findings were examined in eight patients with nonobstructive intraventricular pressure differences resulting from catheter entrapment in obliterated apical portions of the left ventricular cavity. Cardiorespiratory symptoms were reported by six of the eight patients; three had angina pectoris, and two had experienced syncope. A soft systolic ejection murmur was noted at the cardiac apex or left sternal edge, or at both sites, in each patient at rest or following exercise; no patient had a bifid systolic arterial pulse contour. Paradoxical splitting of the second heart sound with respiration did not occur. In five patients the cardiac index was substantially elevated. In four, an intraventricular pressure difference was present in the basal state, while in the remaining four a pressure difference was elicited by the Valsalva maneuver and isoproterenol. In each patient the arterial pulse pressure consistently increased in the beat following a ventricular extrasystole, and angiographic evidence of left ventricular outflow obstruction was not observed. In all patients, obliteration of the apical portion of the left ventricular cavity during systole was demonstrated angiographically to result from an extreme degree of systolic emptying. Left ventricular hypertrophy was demonstrated angiographically in six patients, four of whom exhibited asymmetric hypertrophy, predominantly involving the interventricular septum. In two patients no abnormality of the left ventricular cavity contour was apparent. These clinical, hemodynamic, and angiographic findings allow differentiation of patients with nonobstructive pressure differences from those with hypertrophic subaortic stenosis.