A 5 MHz pulsed Doppler instrument measuring instantaneous maximum and mean flow velocities is presented. The maximum velocity estimator is based on the principle of frequency variable filtering controlled by a feedback loop to follow the velocity spectrum envelope. Findings by Doppler and bilateral selective carotid arteriography in 216 patients were compared. Extracranial carotid stenoses were identified by the finding of a vessel segment with locally increased flow velocity. Peak Velocity Ratio (PVR) was calculated from maximum velocities measured in the stenosis and in more distal Internal Carotid Artery (ICA) segments. Using PVR, ICA stenoses greater than 20% were detected with sensitivity 96%, specificity 94%, positive accuracy 94% and negative accuracy 96%. Total ICA occlusions were identified with sensitivity 97% and specificity 99%.

Adult↗

PubMedDate not supplied

Variations in middle cerebral artery blood flow investigated with noninvasive transcranial blood velocity measurements.

Observations on blood velocity in the middle cerebral artery using transcranial Doppler ultrasound and on the ipsilateral internal carotid artery flow volume were obtained during periods of transient, rapid blood flow variations in 7 patients. Five patients were investigated after carotid endarterectomy. A further 2 patients having staged carotid endarterectomy and open heart surgery were investigated during nonpulsatile cardiopulmonary bypass. The patient selection permitted the assumption that middle cerebral artery flow remained proportional to internal carotid artery flow. The integrated time-mean values from consecutive 5-second periods were computed. The arithmetic mean internal carotid artery flow varied from 167 to 399 ml/min in individual patients, with individual ranges between +/- 15% and +/- 35% of the mean flow. The mean middle cerebral artery blood velocity varied from 32 to 78 cm/sec. The relation between flow volume and blood velocity was nearly linear under these conditions. Normalization of the data as percent of the individual arithmetic means permitted a composite analysis of data from all patients. Linear regression of normalized blood velocity (V') on normalized flow volume (Q') showed V' = 1.05 Q' - 5.08 (r2 = 0.898).

Blood Flow Velocity↗

PubMedDate not supplied

Cerebral panangiography in spontaneous subarachnoid hemorrhage from intracranial aneurysms.

Cerebral panangiography was performed in 594 patients with subarachnoid hemorrhage from intracranial aneurysms. Aneurysm of the middle cerebral arteries was the most frequent location of aneurysms in this material. Multiple aneurysms of the middle cerebral arteries are far more frequent than the combination of other locations. Judged from this material there is a 7 per cent possibility of finding a contralateral aneurysm of the middle cerebral arteries if one is found. Multiple aneurysms were found in 51 (8.6%) of the 594 patients. We conclude that the results of this study are typical for Norwegians, although some selection exists since the patients were first admitted to other hospitals. The frequency of complications with cerebral panangiography in subarachnoid hemorrhage was less than that of cerebral angiography in patients with other diseases.

Adolescent↗