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 cha nges on the coronary flow velocity reserve (CFVR) of the collateral-receivi ng (i.e. ipsilateral) artery, and to test the validity of a model describin g the development of collateral steal. Methods: In 20 patients with one- to two-vessel coronary artery disease (CAD) undergoing angioplasty of one ste notic lesion, adenosine induced intracoronary (i.c.) CFVR during vessel pat ency was measured using a Doppler guidewire. During stenosis occlusion, sim ultaneous 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 adenosin e. From those measurements and simultaneous mean aortic pressure (P-ao). a collateral now index (CFI), and the ipsilateral, collateral, and contralate ral vascular resistance index (R-ipsi, R-coll, R-contra) were calculated. T he study population was subdivided into groups with CFI<0.15 and with CFI<g reater than or equal to>0.15. Results: The percentage-diameter coronary art ery 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. Conclusion s: A hemodynamic interaction between adjacent vascular territories can be d ocumented in patients with CAD and well developed collaterals among those r egions. The CFVR of a collateralized region may, thus, be more dependent on hyperemic vascular resistance changes of the collateral and collateral-sup plying area than on the ipsilateral stenosis severity, and may even fall be low 1. (C) 2001 Elsevier Science B.V. All rights reserved.