The Journal of Thoracic and Cardiovascular Surgery, Vol 82, 350-357, Copyright © 1981 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Effect of nitroprusside on end-diastolic pressure-diameter relations of the human left ventricle after pericardiotomy
CY Wong and HM Spotnitz
Although studies in human beings have suggested that sodium nitroprusside
may increase the diastolic compliance of the left ventricle, animal models
have provided contradictory evidence following pericardiotomy. The effect
of nitroprusside on the human left ventricle after pericardiotomy has not
been reported. Accordingly, we studied the effects of intravenous sodium
nitroprusside in eight patients during cardiac operations. Curves relating
left ventricular end-diastolic pressure (EDP) to echocardiographically
determined end-diastolic diameter (EDD) were determined during the
transfusion of volume from the reservoir of the heart-lung machine (EDP
varied from 5 to 35 mm Hg) before and during nitroprusside administration
(1 to 4 mcg/kg/min). An average relation (EDP = 0.41 +/- 0.40 [SD] e1.18
+/- 0.58 EDD was obtained for eight patients by exponential curve fitting
(r = 0.80 +/- 08). Nitroprusside decreased systolic left ventricular
pressure (118 +/- 16 to 100 +/- 13 mm Hg, p less than 0.001, paired t test)
but did not alter the control curve relating EDP to EDD. We conclude that
EDD-EDP relations of the human left ventricle are not altered by
nitroprusside administration in the absence of the restraining influence of
the pericardium. This suggests that nitroprusside has no significant direct
effect on diastolic properties of the human myocardium.
