Biphasic response of coronary arterial diameter to intracoronary ergonovine.

This report presents a case of paradoxical coronary arterial dilation induced by intracoronary ergonovine. When compared with the control angiogram, the right coronary artery obviously dilated with selective, intracoronary administration of cumulative doses of 5 micrograms and 15 micrograms ergonovine without concomitant hemodynamic changes. Additional intracoronary infusion of 35 micrograms ergonovine into the right coronary artery inversely increased vascular tone of the vessel associated with a focal hyperconstriction. Such a biphasic response of arterial diameter to intracoronary ergonovine was also observed in the left coronary artery, but the degree of dilation was much smaller.