Effect of beta adrenoceptors and thyroid hormones on velocity and acceleration of peripheral arterial flow in hyperthyroidism

Brachial artery flow patterns were studied in 10 hyperthyroid and 10 normal subjects. Mean blood velocity and flow were evaluated by pulsed Doppler, and peak systolic acceleration was calculated by computer-assisted digitization of the instantaneous velocity curve. Compared to control subjects, hyperthyroid patients had higher velocity and flow (p < 0.01, p < 0.02) and higher peak systolic acceleration (p < 0.01). In hyperthyroid patients, measurements were repeated after (1) mechanical exclusion of the hand from brachial circulation, (2) short-term β-blocker treatment and (3) inducement of the euthyroid state. Exclusion of the hand reduced velocity and flow (p < 0.001) but did not change peak systolic acceleration. Beta blockade induced disparate changes of velocity and flow but reduced peak systolic acceleration (p < 0.05). In the euthyroid state, decreased blood velocity (p < 0.01), flow (p < 0.02) and acceleration (p < 0.02) were observed. A hyperkinetic arterial circulation consisting of an increase in both velocity and acceleration is thus observable in hyperthyroidism. Hand exclusion showed that velocity seems to be influenced by peripheral factors while β blockade suggests that acceleration is dependent of β 1 adrenoceptors. Comparison between euthyroidism and hyperthyroidism indicates that both mean blood velocity and peak systolic acceleration are influenced by thyroid hormones.