Peripheral arterial responses to treadmill exercise among healthy subjects and atherosclerotic patients

Abstract

Background - Peripheral cutaneous vascular beds, such as the fingertips, contain a high concentration of arteriovenous anastomoses, richly innervated by α-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 finger pulse-wave amplitude (PWA) responses to exercise among 50 normal volunteers 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 ratio relative to baseline. Exercise PWA responses were compared with clinical, hemodynamic, ECG, and myocardial single photon emission computed tomography parameters. Among normal subjects, 38 (76%) manifested vasodilation throughout exercise and 12 (24%) manifested initial vasodilation followed by vasoconstriction at high heart rate thresholds. None manifested vasoconstriction throughout exercise. By contrast, 20 CAD patients (35%) manifested progressive vasoconstriction from the onset of exercise, and 10 others (18%) manifested vasoconstriction at low heart rate thresholds (P<0.001 versus normals) after initial vasodilation with exercise. Patients exhibiting vasodilation versus vasoconstriction during exercise had similar clinical and exercise profiles, except for a greater use of ACE inhibitors and a greater level 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 phases of treadmill exercise. Such paradoxical vasoconstrictive responses were not observed in normal subjects and, therefore, they may represent generalized vascular pathology secondary to atherosclerosis.