Functional significance of transient collaterals during coronary artery spasm.

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)