Objectives: The purpose of this study was to investigate changes in the magnitude of blood flow through the contralateral coronary artery in relation to the development of recruitable collateral vessels arising from this artery to supply a balloon-occluded coronary vessel.
Background: Recruitable collateral vessels have been shown to emerge suddenly to supply an occluded coronary artery, but their physiologic effect cannot always be predicted angiographically.
Methods: Twenty-four patients were studied during four successive balloon dilations for single left anterior descending coronary artery stenosis. Before and during each balloon occlusion, blood flow in the proximal right coronary artery was measured by intracoronary Doppler flow velocimetry and quantitative coronary angiography. Estimates of chest pain and ST segment elevation were also obtained.
Results: Fourteen patients developed angiographically visible recruitable collateral vessels (high grade in 6 [group III], low grade in 8 [group II]), whereas 10 patients (group I) did not. During the four successive balloon occlusions, the right coronary artery flow showed transient reproducible increases in group III (first occlusion 66.4 +/- 36.8%, fourth occlusion 64 +/- 23.9%, all p = 0.036), progressive increases in group II (from first occlusion 17.9 +/- 26.6% [p = 0.08] to fourth occlusion 60.4 +/- 35.9% [p = 0.014]) and no significant changes in group I. Between the first and the fourth occlusion, the severity of chest pain and the magnitude of ST segment elevation declined significantly in group II but did not change in groups I and III.
Conclusions: During balloon coronary artery occlusion, the transient appearance of recruitable collateral vessels is associated with a transient increase in blood flow through the collateral donor artery. This increase in coronary flow appears to reflect collateral function better than the angiographic assessment, especially in patients with poor collateral vessel recruitment.