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[Collateral circulation during exercise-induced angina: evaluation by coronary angiography]
Insights
Coronary collateral vessels often diminish during exercise-induced angina but remain stable after nitroglycerin administration. This suggests nitroglycerin prevents ischemia by maintaining collateral function during exertion.
Area of Science:
- Cardiology
- Vascular Biology
Background:
- The role of coronary collateral vessels in heart disease pathophysiology is debated.
- Previous studies have not definitively established their behavior during angina.
Observation:
- Coronary angiography visualized collateral vessel changes in 26 patients during ergometer stress tests.
- Collaterals diminished in most patients during exercise-induced angina before nitroglycerin.
- Nitroglycerin administration prevented collateral reduction during angina.
Findings:
- Coronary collateral patency is dynamic and can decrease during exercise-induced angina.
- A pressure gradient between coronary arteries influences collateral function.
- Nitroglycerin administration appears to stabilize collateral circulation during ischemic episodes.
Implications:
- Resting visualization of collaterals does not predict their function during angina.
- Exercise does not necessarily promote collateral circulation development.
- Nitroglycerin may be beneficial in preventing exercise-induced ischemia by preserving collateral flow.
Abstract:
The pathophysiological significance of coronary collateral vessels remains controversial, despite previous intensive studies. We performed the multistage supine ergometer stress test for 26 patients with effort angina and collaterals. The changes in the collaterals were observed during each anginal attack by coronary angiography before and after intravenous nitroglycerin. The collaterals of 21 patients disappeared or diminished during exercise-induced angina before nitroglycerin administration, and were unchanged in the remaining five cases. However, the collaterals of all patients after nitroglycerin administration were unchanged or increased during exercise-induced angina. Considering there were no significant changes in pulmonary arterial end-diastolic pressures during angina before and after nitroglycerin administration, a pressure gradient between the donor and recipient coronary arteries was suggested as being related to the patency of the collaterals. These results suggested the following: 1. It is not appropriate to postulate that the collaterals visualized at rest may remain unchanged during exercise-induced angina. 2. It is not reasonable to conclude that exercise accelerates the development of collateral circulation. 3. One favorable effect of nitroglycerin administration is the prevention of exercise-induced ischemia via collateral circulation.