DIFFERENTIAL-EFFECTS ON RIGHT VENTRICULAR-FUNCTION OF TRANSIENT RIGHT, LEFT ANTERIOR DESCENDING AND LEFT CIRCUMFLEX CORONARY OCCLUSIONS DURING PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY

Right ventricular function was studied by means of a thermodilution catheter before, during and after percutaneous transluminal angioplasty of the proximal right (group 1, n = 8), left anterior descending (group 2, n = 8) or left circumflex (group 3, n = 8) coronary artery. All patients had evidence of myocardial ischemia, with single-vessel disease affecting the proximal segment of one of the three major coronary arteries; no patient had had a previous myocardial infarction and all had normal cardiac function at baseline study. Cardiac index decreased during balloon inflation. Mean pulmonary artery pressure was unaffected in group 1 but increased in group 2 (from 19 +/- 5 to 31 +/- 11 mm Hg, p < 0.01) and in group 3 (from 19 +/- 2 to 22 +/- 5 mm Hg, p < 0.05). Right ventricular ejection fraction decreased from 62 +/- 9% to 52 +/- 10% (p < 0.01) in group 1 and from 64 +/- 7% to 44 +/- 10% (p < 0.005) in group 2, and returned to normal within 2 min after balloon deflation in both groups. In group 3, right ventricular ejection fraction was unchanged during balloon inflation (58 +/- 5% at baseline, 58 +/- 9% at 60 s, p = NS). Therefore, brief occlusion of the proximal segments of the left anterior descending or right coronary artery results in marked alteration of right ventricular performance that is probably caused by right ventricular free wall ischemia in the right coronary group and by the concomitant effects of septal ischemia and increased right ventricular afterload in the left anterior descending artery group. Right ventricular dysfunction might be an additional mechanism of altered cardiac function in patients with acute myocardial infarction caused by occlusion of the proximal left anterior descending or right coronary artery.