The contralateral variation of peak systolic velocity in common carotid arteries.

In order to evaluate the contralateral variation of the peak systolic velocity (Vmax) in common carotid arteries (CCAs), 9 clinically healthy persons (Group A), 11 patients with simple goiter (Group B) and 16 patients with diffuse toxic goiter (Graves' disease, Group C) were referred for radionuclide scanning, duplex Doppler ultrasonography (duplex US) and determination of serum level of the thyroid hormones (T3, T4, T3U) by radioimmunoassay. In Group A, Vmax of right CCA was 98.8 +/- 34.5 cm/sec and that of left CCA was 113.4 +/- 28.9 cm/sec; the left CCA had a higher blood flow velocity than the right one in normal subjects (p less than 0.01). However, the left and right CCA Vmaxes did not significantly differ to each other in Group B (93.5 +/- 21.4 cm/sec vs 98.6 +/- 21.4 cm/sec, p greater than 0.05) and Group C (146.9 +/- 29.3 cm/sec vs 149.9 +/- 28.9 cm/sec, p greater than 0.05). We conclude that there is a contralateral difference of blood flow velocity of common carotid arteries with the left value higher than the right one in healthy persons and this should be kept in mind in evaluation of thyroid functional and carotid arterial diseases.