Effects of adenosine on myocardial blood flow and metabolism after coronary artery bypass surgery.

The effects of adenosine on myocardial blood flow and metabolism, central hemodynamics, and the intrapulmonary shunt fraction were investigated. Fourteen patients with two- or three-vessel coronary artery disease and with an ejection fraction greater than 0.5 were studied in the operating room following sternal closure after elective coronary artery bypass grafting. Systemic and pulmonary hemodynamics and global (coronary sinus), as well as regional myocardial blood flow (great cardiac vein flow), and metabolic variables were measured. Adenosine was given in infusion rates of 15, 30, 60, and 120 micrograms.kg-1.min-1. Infusion rates of 60 and 120 micrograms.kg-1.min-1 decreased mean arterial blood pressure (11% and 16%, respectively), systemic vascular resistance index (30% and 43%), and pulmonary vascular resistance index (24% and 31%), increased cardiac index (25% and 45%), heart rate (14% and 15%), and stroke volume index (9% and 25%), and had no effect on central filling pressures. These infusion rates doubled the intrapulmonary shunt fraction and decreased arterial O2 tension by 26%. Great cardiac vein flow and coronary sinus flow increased 60% with adenosine infusion of 30-60 micrograms.kg-1.min-1 and 120% with 120 micrograms.kg-1.min-1. The ratio of great cardiac vein flow to coronary sinus flow, regional myocardial oxygen consumption, and mean regional lactate extraction and uptake were not significantly altered by adenosine. Adenosine caused a significant depression of the ST segment at infusion rates of 60 and 120 micrograms.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)