Walking With Sir William
Reflections on Collateral Steal, Recruitment, and Ischemic Protection*
Morton J. Kern, MD, FACC, FAHA, FSCAI*
Pacific Cardiovascular Associates, Costa Mesa, California.
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Figure 1 Schematic model of coronary and collateral circulation (left) and experimental measurements (right). Aortic pressure (PAo) is recorded via the guiding catheter. Pressure at the take-off of the collateral in the donor artery (PD) is recorded before recanalization, as well as the coronary flow reserve in the donor artery (CFRD). Collateral blood flow velocity (APVOccl) and pressure (POccl) are recorded distal to the occlusion before balloon dilatation, and CFRR is recorded in the recanalized artery at the end of the procedure. The resistance of the occlusion (ROccl) is infinitesimal, and resistance indexes are calculated to describe the donor resistance (RD), collateral resistance (RC), and microvascular resistance distal to the occlusion (RP). Reproduced from Werner et al. (5).
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Figure 2 Schematic diagrams of conditions that produce recruitable collateral flow (left) and coronary steal (right). Recruitable collateral flow has large donor artery perfusion pressure (Pd) (size of arrow reflects amount of pressure), lower collateral pathway resistance (Rcp), and low collateral bed resistance (Rc). In contrast, collateral steal conditions are associated with a low distal perfusion pressure (Pd or low fractional flow reserve), a higher collateral pathway resistance, and impaired collateral microcirculatory reserve (Rc) (size of arrow reflects amount of coronary reserve); a horizontal arrow means minimal coronary reserve. However, steal can also occur without a donor artery lesion in the presence of an impaired vasodilatory reserve of the microvasculature (14).
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