We conclude that the effects of acute cocaine exposure on ventricular function are predominantly direct but of brief duration and therefore probably not clinically relevant. The effects of cocaine on coronary tone are predominantly indirect and biphasic, with early vasodilation followed by mild and more prolonged vasoconstriction. In the absence of coronary stenosis or ventricular hypertrophy, this small amount of vasoconstriction is unlikely to cause ischemia.

Coronary flow response to low-dose (5 and 10 micrograms/kg/min) dobutamine infusion was used to assess myocardial viability at the time of cardiac catheterization in 13 patients (age, 60 +/- 11 years) with recent myocardial infarction. Echocardiographic improvement in regional wall motion performed 4 to 6 weeks after discharge was used as the marker for viability. Viable patients demonstrated a 2-fold increase in flow from baseline (p < 0.001) during intravenous infusion. In contrast, patients without viability demonstrated no increase in flow. The coronary flow response to dobutamine measured at the time of catheterization shows promise in identifying viable myocardium in postinfarction patients.

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