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

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 minutes. In eight patients averaging 21 ± 7 (SEM) minutes of arrest, the authors saw no change in LVEDP-LVEDD curves. In five patients averaging 55 ± 15 minutes of arrest, they noted temporary alterations in EDP-EDD curves (p<0.05). The curves returned to normal within 30-60 minutes after ischemia. In two patients with an average of 66 minutes of arrest, they observed changes in the EDP-EDD curves which did not revert to normal. Available data did not allow to distinguish between impaired ventricular relaxation and a true change in ventricular compliance as a cause of the shift in the EDP-EDD curve, but ischemia appears to be a major factor in the observed changes. Increased LVEDP after ischemic arrest during open heart surgery may reflect a decrease in left ventricular compliance, rather than an increase in heart size. The probability of altered LVEDP-LVEDD relations appears to depend on the duration of ischemic arrest.