Effects of open heart surgery on end-diastolic pressure-diameter relations of the human left ventricle.

Abstract

Curves relating left ventricular end-diastolic pressure (LVEDP) to echocardiographically determined end-diastolic diameter (LVEDD) were obtained before and after ischemic arrest in 15 patients during open heart surgery. LVEDP ranged from 0-20 mm Hg during routine operation of the heart-lung machine. Ischemic arrest ranged from 0-94 min. In 8 patients averaging 21 .+-. 7 (SEM [standard error of the mean]) minutes of arrest, no change occurred in LVEDP-LVEDD curves. In 5 patients averaging 55 .+-. 15 min of arrest, temporary alterations occurred in EDP-EDD curves (P < 0.05). The curves returned to normal within 30-60 min after ischemia. In 2 patients with an average of 66 min of arrest, changes in the EDP-EDD curves occurred which did not revert to normal. Impaired ventricular relaxation and a true change in ventricular compliance could not be distinguished as a cause of the shift in the EDP-EDD curve, but ischemia may be a major factor in the changes. Increased LVEDP after ischemic arrest during open heart surgery may reflect decreased left ventricular compliance rather than an increase in heart size. The probability of altered LVEDP-LVEDD relations may depend on the duration of ischemic arrest.