Changes in myocardial blood flow and systemic hemodynamics during hypotensive anesthesia induced by adenosine triphosphate with or without dipyridamole]

The changes in myocardial blood flow and systemic hemodynamics during hypotensive anesthesia with adenosine triphosphate (ATP) or ATP with dipyridamole (0.5 mg.kg-1) were studied in 20 mongrel dogs anesthetized with 0.7% halothane in 100% oxygen. In both groups, mean arterial blood pressure (MAP) was reduced to 60 mmHg by intravenous administration of ATP. During hypotensive anesthesia, coronary blood flow, myocardial blood flow and cardiac index increased significantly in both groups. Lactic acid and uric acid increased significantly during hypotensive anesthesia in the group 1. Heart rate, MAP, systemic vascular resistance and coronary vascular resistance decreased significantly during hypotensive anesthesia in both groups. Mean pulmonary arterial pressure, pulmonary arterial wedge pressure and central venous pressure showed no significant changes in both groups. Base excess in the group 1 increased markedly compared with the group 2. We conclude that pretreatment with dipyridamole can prevent metabolic acidosis that occurs during hypotensive anesthesia induced by ATP.