Peripheral arterial responses to treadmill exercise among healthy subjectsand atherosclerotic patients

Background-Peripheral cutaneous vascular beds, such as the fingertips, cont ain a high concentration of arteriovenous anastomoses, richly innervated by alpha -adrenergic nerve fibers, to control heat regulation, Nevertheless, for a variety of technical reasons, finger blood flow responses to exercise have not been well studied in health and disease. Hence, we compared finge r pulse-wave amplitude (PWA) responses to exercise among 50 normal voluntee rs and 57 patients with atherosclerotic coronary artery disease (CAD) using a robust, modified form of volume plethysmography. Methods and Results-PWA was quantified for each minute of exercise as a rat io relative to baseline. Exercise PWA responses were compared with clinical , hemodynamic, EGG, and myocardial single photon emission computed tomograp hy parameters. Among normal subjects, 38 (76%) manifested vasodilation thro ughout exercise. and 12 (24%) manifested initial vasodilation followed by v asoconstriction at high heart rate thresholds. None manifested vasoconstric tion throughout exercise. By contrast, 20 CAB patients (35%) manifested pro gressive vasoconstriction from the onset of exercise, and 10 others (18%) m anifested vasoconstriction at low heart rate thresholds (P<0.001 versus nor mals) after initial vasodilation with exercise. Patients exhibiting vasodil ation versus vasoconstriction during exercise had similar clinical and exer cise profiles, except for a greater use of ACE inhibitors and a greater lev el of achieved metabolic equivalents among the former (P<0.05 for both). Conclusions-Half of our CAD patients manifested diminution in PWA that was consistent with peripheral arterial vasoconstriction during the early phase s of treadmill exercise. Such paradoxical vasoconstrictive responses were n ot observed in normal subjects and? therefore, they may represent generaliz ed vascular pathology secondary to atherosclerosis.