Detection of reverse flow by duplex ultrasonography in orthostatic hypotension.

Objective: The aim of this study is to elucidate the effect of orthostatic hypotension on changes in cerebral blood flow.

Methods: Blood flow velocities of both the common carotid artery and vertebral artery were measured using duplex ultrasonography in 12 patients: 6 with familial amyloidotic polyneuropathy, 3 with Shy-Drager syndrome, 2 with pandysautonomia, and 1 with senile orthostatic hypotension. Simultaneously, peripheral blood flow was also evaluated by laser-Doppler flowmetry.

Results: The patients showing dizziness or syncope when tilted to a 70 degrees upright position exhibited characteristic reverse flow at the end-diastolic phase on the Doppler flow image of both the common carotid and vertebral arteries, which was effectively treated by infusion of 2.5 micrograms/min norepinephrine for 10 minutes. This end-diastolic reverse flow was not seen in any patients who did not have dizziness or syncope. After subjects were tilted from a supine to a 70 degrees upright position, decrease in the peripheral blood flow of the patients with orthostatic hypotension remained unchanged for at least 5 minutes, whereas that of control subjects was recovered within 2 minutes. However, no significant difference between the patients with and without clinical symptoms was observed.

Conclusions: These results suggest that detection of this specific echographic pattern may be quantitatively useful in examination of clinical symptoms accompanying orthostatic hypotension and that duplex ultrasonography may be a helpful tool to evaluate the effect of drugs used for controlling these clinical signs.