The reactivity of the contralateral artery at the time of balloon dilation during coronary angioplasty.

The response of the contralateral arteries was investigated during balloon angioplasty of the left anterior descending artery. Thirty patients were studied. Coronary arteriograms were obtained at baseline, during maximal balloon inflation and at the end of the procedure. Luminal diameter was measured by a quantitative coronary arteriography analysis system. During balloon inflation the luminal diameter of the proximal segment of the right coronary artery increased by 2.4 +/- 6% (P < 0.05), and that of the left circumflex artery increased by 0.6 +/- 6% (P = ns). Both returned to near baseline values after angioplasty. In patients with increased collaterals during balloon inflation the left circumflex proximal segment increased more significantly than in patients with unchanged collaterals. The luminal diameter of the distal segment of the right coronary artery increased by 9 +/- 8% (P < 0.001) and that of the left circumflex artery by 8 +/- 11% (P < 0.01) during balloon inflation, returning to near baseline values after angioplasty. Thus, vasodilation of the contralateral arteries during balloon inflation at the time of coronary angioplasty occurs mainly in the distal segments, and appears to be related to an increase in collateral filling.