Collateral and collateral-adjacent hyperemic vascular resistance changes and the ipsilateral coronary flow reserve: Documentation of a mechanism causing coronary steal in patients with coronary artery disease

Objectives: The goal of this clinical study was to assess the influence of hyperemic ipsilateral, collateral and contralateral vascular resistance changes on the coronary flow velocity reserve (CFVR) of the collateral-receiving (i.e. ipsilateral) artery, and to test the validity of a model describing the development of collateral steal. Methods: In 20 patients with one- to two-vessel coronary artery disease (CAD) undergoing angioplasty of one stenotic lesion, adenosine induced intracoronary (i.c.) CFVR during vessel patency was measured using a Doppler guidewire. During stenosis occlusion, simultaneous i.c. distal ipsilateral flow velocity and pressure (P-occl, using a pressure guidewire) as well as contralateral flow velocity measurements via a third i.c. wire were performed before and during intravenous adenosine. From those measurements and simultaneous mean aortic pressure (P-ao). a collateral now index (CFI), and the ipsilateral, collateral, and contralateral vascular resistance index (R-ipsi, R-coll, R-contra) were calculated. The study population was subdivided into groups with CFI<0.15 and with CFI<greater than or equal to>0.15. Results: The percentage-diameter coronary artery stenosis (%-S) to be dilated was similar in the two groups: 78 +/- 10% versus 82 +/- 12% (NS). CFVR was not associated with %-S. In the group with CFI greater than or equal to0.15 but not with CFI<0.15, CFVR was directly and inversely associated with R-coll and R-contra, respectively. Conclusions: A hemodynamic interaction between adjacent vascular territories can be documented in patients with CAD and well developed collaterals among those regions. The CFVR of a collateralized region may, thus, be more dependent on hyperemic vascular resistance changes of the collateral and collateral-supplying area than on the ipsilateral stenosis severity, and may even fall below 1. (C) 2001 Elsevier Science B.V. All rights reserved.