Hemodynamics of the Upper Extremities in Subelavian Steal Syndrome

ness of the importance of obstructive lesions of the proximal subclavian artery in the production of symptoms of cerebral ischemia. Since this is a form of cerebral vascular insufficiency readily improved or cured by surgery, it is imperative that the "steal" syndrome be suspected clinically and that appropriate diagnostic procedures be performed. Symptoms of brainstem ischemia coupled with brachial blood pressure inequality, subclavian bruit, and ipsilateral radial pulse delay as observed by Kesteloot and Houte,2 are the basic clinical criteria for selection of these patients for contrast procedures. Experiments in which chronic reversal of vertebral flow was created in dogs3' 4 suggested that plethysmographically recorded alterations in digital pulse contour, timing, and blood flow in the occluded extremity could be of diagnostic importance. The present studies, carried out on patients with symptomatic subclavian steal, amplify our previous findings in animals and demonstrate pulse delay and the decrease in pulse amplitude in the extremity distal to the subclavian occlusion. The clinically observed diminution or loss of radial pulse following exercise of the arm with subclavian stenosis or occlusion has been confirmed objectively. Furthermore, we have found a compensatory dilatation of cutaneous vascular bed on the side of the obstruc-