Regional myocardial blood flow in man during dipyridamole coronary vasodilation

Regional myocardial blood flow before and after intravenous dipyridamole (0.56 mg/kg) was measured during cardiac catheterization in 11 patients using the ¹³³Xe washout technique. Significant increases in heart rate (75 ± 4 vs 87 ± 6, p < 0.004) and decreases in systolic blood pressure (144 ± 8 vs 131 ± 7, p < 0.02) were observed with dipyridamole infusion. However, double product and cardiac output did not differ before or after drug infusion. Regional myocardial blood flow increased from 67 ± 3 (SEM) to 117 ± 3 ml/100 mg/min in myocardial segments supplied by nonobstructed coronary arteries. In stenotic coronary arteries, flow increased from 57 ± 5 to 79 ± 9 ml/100 mg/min with dipyridamole. We conclude that dipyridamole infusion results in flow differences which discriminate stenotic from nonstenotic coronary arteries.