Hemodynamic evaluation of vertebral arteries by duplex ultrasound.

In summary, vertebral artery hemodynamics can be readily evaluated both qualitatively and quantitatively. Duplex ultrasonography provides a very reliable noninvasive technique for this assessment. Flow in the vertebral artery system can be noninvasively quantified in greater than 95 per cent of all patients examined using this technique, and such measurements help identify subgroups of patients whose symptoms may be related to posterior circulation ischemia. Further evaluation of the spectral flow patterns is often helpful in diagnosing the cause of these ischemic symptoms. Unfortunately, quantitative flows are rarely obtained during routine carotid ultrasound studies. Such data, however, may provide an objective basis for the following kinds of surgical decisions: 1. Recommendations for carotid surgery in patients with high-grade carotid stenosis but nonlocalizing symptoms. 2. Recommendations for no surgery in patients who have vertebrobasilar symptoms but diminished flow characteristic of poor cardiac output. 3. Recommendations for surgery to augment vertebral artery flow in patients who have vertebrobasilar symptoms, decreased vertebral flow on the basis of proximal stenosis, and normal carotid artery flow. Obviously, there is a need to confirm these hypotheses by studying patients thoroughly before and after surgery. Other investigators must begin gathering data on vertebral artery flow to determine its impact and utility in making surgical decisions.