[Influence of nitrates on regional myocardial blood flow and left ventricular wall motion].

Regional myocardial blood flow was measured by means of a computerized gamma-camera system in 30 patients with coronary artery disease (CAD) and in 14 healthy control subjects. Ventricular wall motion was quantitatively analyzed in 65 CAD-patients. Global and semiregional blood flow measurements yielded only limited information. In contrast, measurements of regional blood flow permitted detection of hypoperfused myocardium and the effects of pharmacologic intervention. The administration of 15 mg isosorbide dinitrate (ISDN) resulted in an increase in blood flow in post-stenotic hypoperfused myocardial regions of 20p.c. and a decrease in flow through normal myocardium of 14 p.c. These observations represent the adaption of flow to a newly-established level of metabolic demand. This increase in blood flow coupled with a reduction in afterload leads to improved ventricular wall motion in 65-75 p.c. of areas of hypokinetic myocardium and, to a markedly lesser degree, in only 20-25 p.c. of akinetic regions. Dyskinetic regions show no improvement. As compared with the 13ml/loog/min increase in blood flow seen after intracoronary administration of 0.45 mg ISDN in normal coronary vessels, the compromised dilatory capacity of diseased coronary vessels results in a relatively small increase in flow of 6 ml/100 g/min. The reduction of the extravascular component of coronary resistance, thus, appears to be the mechanism primarily responsible for the therapeutic effect of nitrates.