The haemodynamic effect of an intracranial arteriovenous anomaly. A Doppler-haematotachographic study.

Determination of the mean blood flow velocity by means of Doppler haematotachography is suggested as an aid in evaluating the haemodynamic changes associated with an intracranial arteriovenous anomaly. A Doppler haematotachogram (HTG) was obtained in 13 patients with a radiologically diagnosed arteriovenous anomaly, with marked interindividual variations in dimensions and blood supply; in 6 of these patients the Doppler HTG was obtained before and after total neurosurgical extirpation. The large majority of the patients showed a significant increase in diastolic, and to a lesser degree in systolic flow velocity at the level of the common carotid artery. In most cases the flow velocity curve of the ophthalmic artery showed a decrease in amplitude. These are the most useful parameters in evaluating the haemodynamic effect of an intracranial arteriovenous anomaly. After the surgical removal of the anomaly, the carotid flow velocity decreased significantly. In the internal and external jugular veins, Doppler-haematotachographic pulse waves were registered for the first time. These may have been conducted from the internal carotid artery to the jugular veins via the arteriovenous anomaly. The usefulness of this parameter is reduced because of the cumbersome calculations required to determine the time within which an arterial pulse wave conducted via the arteriovenous anomaly reaches the jugular vein. Registration of this unusual pulse wave is solely of theoretical value.