Non-Beta-Adrenergic-Mediated Peripheral Circulatory Hyperkinesia in Hyperthyroidism

Abstract

Systolic time intervals and brachial circulation, evaluated by pulsed Doppler in terms of arterial diameter, blood velocity and flow, and vascular resistance, were studied in 12 hyperthyroid patients and in 12 normal controls. In patients, arterial circulation was studied before and during mechanical exclusion of the hand, and hemodynamic measurements were repeated after beta-blocker treat ment and after obtainment of euthyroid state. Compared with controls, patients had higher heart rate (P < 0.001), lower systolic time intervals (P < 0.05, P < 0.01), and higher blood velocity (P < 0.05). Beta blockade decreased heart rate (P < 0.05, P < 0.001) but did not change systolic time intervals and arterial circulation. Euthyroid state decreased heart rate (P < 0.01), preejection period (P < 0.01), and blood velocity (P < 0.01) and flow (P < 0.05). The decreases in velocity and flow before hand exclusion when euthyroid state was obtained were correlated with hyperthyroid values of velocity and flow respectively (r = 0.85, r = 0.90, P < 0.01, P < 0.001). Vascular resistance during hand exclusion was correlated negatively with serum T₃ level during hyperthyroid and euthyroid states. Thus, thyroid hormones but not beta-adrenoreceptors participate in the peripheral hyperkinesia of hyperthyroidism.