Improvement of ST Segment Depression by Gradual Recruitment of Collateral Circulation

Abstract

The purpose of the present study was to document that the coronary collateral vessels do not open immediately upon the occurrence of myocardial ischemia. A multistage bicycle exercise was performed to determine a maximal tolerable work load until the onset of angina and significant ST segment depression in 10 patients with well-developed collateral circulation. On a different day, exercise with the maximal tolerable work load was repeated for a comparable exercise duration. In 2 of the 10 patients, anginal pain was gradually alleviated despite the continuation of exercise with fixed work load. The extent of ST segment depression at 3 min of exercise with fixed work load was 0.20 ± 0.10 (SD) mV, significantly (p < 0.05) greater than 0.16 ± 0.08 mV at the end of exercise with fixed work load. In contrast, the rate-pressure product was smaller at 3 min than at the end of exercise with fixed work load (20,900 ± 5,500 vs. 22,700 ± 5,700 mm Hg · beats/min; p < 0.05). In 5 patients without well-developed collateral circulation, the extent of ST depression changed in parallel with changes in rate-pressure product during exercise with fixed work load. Thus, it is concluded that the delayed collateral opening plays a critical role in the pathogenesis of myocardial ischemia in patients with a totally occluded coronary artery.

Recent insights into coronary collateral circulation.

“…In 10 patients with welldeveloped collateral circulation, the extent of ST depression at 3 minutes of bicycle exercise with fixed work load was 0.20 mV, but this depression was significantly reduced to 0.16 mV at the end of exercise when the double product was 9% greater than that at 3 minutes of exercise. 46 Takeshita and coworkers48 have observed for the first time that angiographically demonstrable collaterals appeared immediately when coronary arterial spasm was induced by ergonovine in two patients with transient recurrent myocardial ischemia caused by arterial spasm. Similarly, a reduction in coronary luminal diameter by more than 70% was shown to be accompanied by angiographically demonstrable collaterals during coronary occlusion using an angioplasty balloon with 100% specificity and 85% sensitivity.…”

Acute Myocardial Infarction without Warning: Clinical Characteristics and Significance of Preinf arction Angina

“…Coronary collateral channels play an im portant role in preventing the ischemia pro voked by exercise [ 1 ] or by transient coronary occlusion during angioplasty [2] in patients with coronary artery disease. Findings ob tained from emergency coronary angiography performed in the early phase of acute myocar dial infarction (AMI) also suggest that coronary collateral channels protect against myo cardial damage and preserve ventricular func tion [3][4][5][6][7], Recruitable collateral channels during coronary occlusion are related to the preexisting critical coronary stenosis [8].…”

Conceptual Framework of Collateral-promoting Therapy for Coronary Artery Disease

“…3,4 Collateral recruitment is responsible for the walk-through phenomenon in angina patients with a well-developed collateral circulation. 5 The principal mechanism of collateral recruitment is collateral flow-dependent dilation of pre-existing collateral vessels with several layers of muscular media. 6…”