Propranolol-induced Reverse Vascular Steal in Arteriopathic Patients

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Abstract
The vascular steal phenomenon, i.e., the shunting of blood from ischemic to normally perfused areas, has been described in the affected limbs of arteriopathic patients after taking vasodilating drugs. This study was per formed to ascertain whether the reverse situation can be induced, i.e., whether vasoconstriction of the vessels supplying the nonischemic zone could increase the amount of blood reaching the ischemic area. Accordingly, 49 arteriopathic subjects were selected on the basis of the plethysmographic evidence of a reduction of blood flow in the affected limb following an IV injection of xanthinol-nicotinate. In a first group of 10 patients, the reduction of blood supply to the affected limb induced by xanthinol-nicotinate was inhibited when this drug was administered in combination with 5 mg of propranolol. In another 22 patients, the plethysmographic response observed after xanthinol-nicotinate alone was reversed when this drug was injected after 10 mg of propranolol. Actually, the blood perfusion to the affected limb rose significantly at all times of recording as compared to basal values. Finally, in a third group of 10 patients in whom xanthinol-nicotinate induced a significant reduction of blood flow, propranolol did not modify it. The angiographic studies performed in 3 patients confirm the plethysmographic results. Xanthinol-nicotinate alone induces a reduction of the vascular filling in the affected limb, while the combination of the vasodilating drug with 10 mg of propranolol is able to improve the vascular filling in the affected area. These results indicate that the overwhelming action of α-adrenoceptors obtained in the normal area by the β-receptors' blockade favors a beneficial redistribution of blood flow which might be considered a reverse vascular steal.