Effects of intracoronary injection of acetylcholine on coronary arterial diameter.

The effects of intracoronary injection of acetylcholine on coronary arterial diameter was examined by coronary arteriography in 30 adult patients (13 men, 17 women), aged 23 to 67 years (mean 51), with normal or almost normal coronary arteriographic findings. Patients with angina pectoris, myocardial infarction and other severe cardiac diseases were excluded. Two minutes after injection of 30 to 100 micrograms of acetylcholine into the left coronary artery, significant diffuse narrowing (more than 25% reduction in diameter) of the left main trunk, the proximal, mid- and distal left anterior descending artery, and the proximal, mid- and distal left circumflex artery occurred in 1 (4%), 5 (20%), 3 (12%), 9 (36%), 6 (24%), 8 (32%) and 3 (12%) of 25 patients, respectively. After injection of 30 to 50 micrograms of acetylcholine into the right coronary artery, significant diffuse narrowing of the proximal, mid- and distal right coronary artery occurred in 5 (25%), 7 (35%) and 10 (50%) of 20 patients, respectively. However, significant diffuse dilatation (more than 25% increment in diameter) appeared in the left main trunk, left anterior descending, left circumflex and right coronary arteries in a few patients. These results indicate that acetylcholine induces coronary vasoconstriction in a significant number and coronary vasodilatation in a small number of adult humans, and that response of the coronary artery to acetylcholine varies along the course of the coronary artery.