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Functional significance of transient collaterals during coronary artery spasm
Insights
Coronary collaterals improve blood flow during vasospasm, reducing ischemia. Patients with collaterals had greater residual great cardiac vein flow and lower coronary resistance during spasm.
Area of Science:
- Cardiology
- Physiology
Background:
- Coronary collateral vessels can transiently appear during vasospasm.
- Their functional significance in acute myocardial ischemia requires further investigation.
Purpose of the Study:
- To examine the functional role of coronary collaterals in acute myocardial ischemia during vasospasm.
- To compare regional coronary flow in patients with and without collaterals during ergonovine-induced spasm.
Main Methods:
- Assessed regional coronary flow in two groups of patients during isolated total spasm of the left anterior descending coronary artery.
- Group I (n=7) had collaterals; Group II (n=9) did not.
- Measured great cardiac vein flow (GCVF) using thermodilution and calculated coronary collateral resistance index.
Main Results:
- Patients with collaterals (Group I) had significantly higher pulmonary artery end-diastolic pressure and greater residual GCVF during vasospasm compared to those without (Group II).
- Coronary collateral resistance index was significantly lower in Group I than in Group II.
- Spasm with collaterals was less frequently associated with ST elevation.
Conclusions:
- Coronary collaterals play a significant functional role in maintaining myocardial perfusion during vasospasm.
- The presence of collaterals reduces the severity of ischemia during acute coronary events.
Abstract:
Coronary collateral vessels appear transiently during vasospasm. To examine the functional role of such collaterals in acute myocardial ischemia, regional coronary flow was determined in patients who showed isolated total spasm in the proximal left anterior descending coronary artery associated with (n = 7, group I) and without (n = 9, group II) collaterals, which were donated by the nonspastic right coronary artery during ergonovine provocative test. Aortic pressure and heart rate were not significantly different in the 2 groups before and during spasm. During vasospasm, the levels of pulmonary artery end-diastolic pressure were significantly higher in group II (19 +/- 2 mm Hg, mean +/- standard error) than in group I (15 +/- 1 mm Hg, p less than 0.05). Under these conditions, great cardiac vein flow (GCVF) measured by thermodilution was markedly reduced in group II (from 60 +/- 4 ml/min to 37 +/- 4 ml/min, p less than 0.01), whereas GCVF was slightly reduced in group I (from 56 +/- 4 ml/min to 51 +/- 4 ml/min), indicating that residual GCVF was greater in patients with than in those without collaterals (p less than 0.05). The calculated coronary collateral resistance index during vasospasm was significantly lower in group I (2.06 +/- 0.18 mm Hg min/ml) than in group II (2.91 +/- 0.30 mm Hg min/ml, p less than 0.05). Total left anterior descending coronary artery spasm with collaterals was less frequently associated with ST elevation in the precordial electrocardiogram recorded during spasm.(ABSTRACT TRUNCATED AT 250 WORDS)