Peroperative myocardial ischemia and citrate administration: cardiovascular adaptability in conscious dogs

Since the hemodynamic response elicited by the administration of citrate is sensitive to alterations in the baseline cardiovascular status, we have investigated the consequences of peroperative myocardial ischemia upon this hemodynamic response. 19 dogs equipped with an electromagnetic flow probe positioned around the ascending aorta served as control (group I). 16 dogs were equipped similarly and in addition submitted to 1 h of myocardial ischemia combined with topical cardiac hypothermia (group II). Hemodynamic studies were carried out 3 h postoperatively and then daily for 1 month, before and during rapid intravenous administration of citrate. From baseline hemodynamic data, cardiac failure was only evident 3 h postoperatively in group II. Transient hypotension and myocardial depression resulted from administration of citrate in both groups with no evidence of peripheral vasodilation. Hypotension and the negative inotropic response were more pronounced in the presence of cardiac failure following peroperative myocardial ischemia. Long-term studies indicate that global myocardial ischemia did not interfere with the cardiovascular adaptability to this pharmacologic interference.