TY - JOUR
T1 - Effect of nitroglycerin and dipyridamole on regional left ventricular blood flow during coronary artery occlusion
AU - Becker, L. C.
PY - 1976
Y1 - 1976
N2 - Coronary vasodilators have been variously reported to increase, decrease, or have no effect upon blood flow to ischemic myocardium. Consequently, the effects of two different types of dilators, nitroglycerin (TNG) and dipyridamole, were studied with radioactive microspheres in open chested dogs after coronary artery ligation. Given as a bolus i.v. injection, 0.4 mg TNG resulted in an increase in blood flow to nonischemic areas of myocardium and a preservation of flow to ischemic regions, despite a fall in blood pressure. 5 min later blood pressure and nonischemic flow were back to base line, and a small selective increase in flow to ischemic myocardium was found (0.15-0.18 ml/min per g, P<0.05). During an 0.2 mg/min infusion of TNG, and also after 1 mg/kg i.v. dipyridamole, ischemic flow was maintained in the face of a 20-30% reduction in blood pressure. In this setting, nonischemic flow was unchanged during TNG and doubled after dipyridamole. With the addition of methoxamine in both dilator groups, blood pressure returned to base line while flow to ischemic areas increased above base line values (TNG, 0.16-0.20 ml/min per g, P<0.01; dipyridamole, 0.18-0.31 ml/min per g, P<0.05). Epicardial ST segment elevations increased during TNG infusion and were unchanged after dipyridamole, but with addition of methoxamine, ST segments became less elevated in both drug groups, concomitant with the observed increase in collateral blood flow. These data indicate that both types of coronary vasodilators, when used in conjunction with methoxamine to support blood pressure, reduce collateral resistance, increase collateral flow, and reduce epicardial ST segment elevations.
AB - Coronary vasodilators have been variously reported to increase, decrease, or have no effect upon blood flow to ischemic myocardium. Consequently, the effects of two different types of dilators, nitroglycerin (TNG) and dipyridamole, were studied with radioactive microspheres in open chested dogs after coronary artery ligation. Given as a bolus i.v. injection, 0.4 mg TNG resulted in an increase in blood flow to nonischemic areas of myocardium and a preservation of flow to ischemic regions, despite a fall in blood pressure. 5 min later blood pressure and nonischemic flow were back to base line, and a small selective increase in flow to ischemic myocardium was found (0.15-0.18 ml/min per g, P<0.05). During an 0.2 mg/min infusion of TNG, and also after 1 mg/kg i.v. dipyridamole, ischemic flow was maintained in the face of a 20-30% reduction in blood pressure. In this setting, nonischemic flow was unchanged during TNG and doubled after dipyridamole. With the addition of methoxamine in both dilator groups, blood pressure returned to base line while flow to ischemic areas increased above base line values (TNG, 0.16-0.20 ml/min per g, P<0.01; dipyridamole, 0.18-0.31 ml/min per g, P<0.05). Epicardial ST segment elevations increased during TNG infusion and were unchanged after dipyridamole, but with addition of methoxamine, ST segments became less elevated in both drug groups, concomitant with the observed increase in collateral blood flow. These data indicate that both types of coronary vasodilators, when used in conjunction with methoxamine to support blood pressure, reduce collateral resistance, increase collateral flow, and reduce epicardial ST segment elevations.
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U2 - 10.1172/JCI108584
DO - 10.1172/JCI108584
M3 - Article
C2 - 825534
AN - SCOPUS:0017135309
SN - 0021-9738
VL - 58
SP - 1287
EP - 1296
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 6
ER -