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Supraorbital artery blood flow was examined non-invasively with continuous wave Doppler-shifted ultrasound and spectral analysis. The results were used to assess the ipsilateral internal carotid artery in 155 patients undergoing carotid angiography. The ultrasound parameters used were the temporal artery occlusion test and A/B ratios of both resting and augmented supraorbital sonagrams. A retrospective study showed this combination to have a sensitivity of 65% for internal carotid disease which did not encroach on the lumen and for all other angiographically demonstrated lesions an average sensitivity of 94% and specificity of 92%. Augmented supraorbital pulses were more sensitive for detection of carotid artery disease than resting supraorbital pulses. Of the 61 lesions in which both resting and augmented supraorbital A/B ratios were obtained, the augmented supraorbital pulse detected 48 (79%) whilst the resting supraorbital pulse detected 29 (48%). Localised carotid bruits were poor indicators of carotid artery disease, having a sensitivity of only 27%.

Using continuous wave Doppler-shifted ultrasound and spectral analysis the response to the temporal artery occlusion test was compared when insonating the supraorbital and supratrochlear arteries of 203 internal carotid pathways. The test involved monitoring the periorbital artery whilst simultaneously compressing a single branch of the external carotid artery, the ipsilateral superficial temporal artery. In 41 instances carotid angiography demonstrated severe disease of the internal carotid artery, that is lesions of 75% or more reduction in lumen diameter. A positive response to the temporal artery occlusion test, when performed on the supraorbital artery, indicated severe disease with a sensitivity of 90% and a specificity of 89%. When this test was performed on the supratrochlear artery a low sensitivity of 36% was obtained, although specificity was high at 96%.

Doppler-shift ultrasound with spectral analysis permits the measurement of the relative heights of systolic peaks (the A/B ratio) in blood velocity sonograms from supra-orbital and common carotid arteries, the temporal artery occlusion test, the common carotid resistance index and transit times of flow-velocity waves in the internal carotid pathway. The results are compared with 201 carotid angiograms and expressed in terms of sensitivity (true positive) and specificity (true negative). Supra-orbital and common carotid A/B ratios, in combination with the temporal artery occlusion test, detected all grades of carotid artery disease with a sensitivity of 72 per cent and a specificity of 93 per cent. The corrected transit time gave a sensitivity of 57 per cent and a specificity of 89 per cent, whilst the Resistance Index gave a sensitivity of 60 per cent and a specificity of 80 per cent. The values of ultrasound parameters associated with severe disease, defined as reductions in lumen diameter of 75 per cent or more, of the internal carotid artery are examined. The temporal artery occlusion test gave a sensitivity of 91 per cent and a specificity of 94 per cent. These results were more accurate than those obtained for the corrected transit time (sensitivity 83 per cent, specificity 92 per cent) and for the Resistance Index (sensitivity 75 per cent and specificity 92 per cent). The results show that of the tests described the supra-orbital and common carotid artery A/B ratios, together with the temporal artery occlusion test, gave the best sensitivity and specificity for detection of both severe and minor carotid bifurcation disease.

Doppler-shifted ultrasound was used as a non-invasive test to determine the presence of severe (pressure dropping) internal carotid lesions in two groups of elderly patients. Group 1 consisted of 150 hypertensive patients; these were subdivided into 77 who had had no cerebrovascular incidents (mean age 75 years, range 65-97) and 73 who had previously suffered a stroke (mean age 75 years, range 65-91). Group 2 consisted of 44 normotensive asymptomatic elderly volunteers (mean age 76 years, range 68-90). In the hypertensive patients (group 1), severe disease was detected in the non-stroke patients in 15 (10%) of the internal carotid arteries (14% of the patients), and in the stroke patients in 23 (16%) of the internal carotid arteries (23% of the patients). None of the normotensive volunteers (group 2) had evidence of severe internal carotid disease. Statistical analysis confirmed a highly significant difference in the prevalence of severe carotid disease between the normotensive and hypertensive subjects. The difference between the non-stroke and stroke hypertensive patients was not statistically significant.

Doppler-shifted ultrasound and spectral analysis were used to assess the carotid arteries of 77 elderly stroke patients, which represented 154 carotid bifurcations. Severe carotid disease was demonstrated at 19 of the 154 carotid bifurcations and in eight of these complete occlusion of the internal carotid artery was present. In 12 of the 19 instances the severe disease was in the internal carotid artery associated with the stroke. Localized carotid bruits were present in five patients and only three of these were associated with severe disease of the internal carotid artery. Minor disease was detected in 80 of the 154 carotid bifurcations and no disease was detected at the remaining 55 carotid bifurcations. An abnormally low ankle/arm systolic pressure ratio, which indicated occlusive arterial disease of the legs, was obtained in 19 of the 43 patients examined. No relationship was found between the severity of carotid artery disease and the presence of haemodynamically significant disease of the lower limbs. Ultrasound measurement of aortic compliance gave significantly lower values in elderly stroke patients compared to elderly asymptomatic volunteers. Comparison of flow-velocity transit times from the stroke-affected and non-affected limbs showed no consistent effect of the stroke on vascular tone in the patients assessed.

Transcranial pulsed Doppler ultrasound and spectral analysis were used for detection of blood velocities in the basal cerebral arteries. The Doppler transducer was placed superior to the zygomatic arch and during insonation of the middle cerebral artery care was taken to obtain maximum Doppler-shift frequency signals since this allowed a small angle between the ultrasound beam and this artery. Doppler signals were obtained from the middle, anterior, and posterior cerebral arteries in 20 volunteers with the average depth of the Doppler gate at 4.9 (4.6-5.2 cm), 5.2 (4.9-5.4 cm), and 6.3 cm (6.0-6.9 cm), respectively. These measurements were in agreement with those obtained for 15 cadaver studies, in whom the distance from the proposed site of the Doppler transducer to each basal cerebral artery was measured as 4.7 +/- 0.6, 5.3 +/- 0.5, and 5.9 +/- 0.9 cm, respectively. The reproducibility of middle cerebral artery blood velocity values was tested in seven subjects and showed a variation of not more than 8% in any individual. The method was used in combination with common carotid compression to assess four patients who had occlusive extracranial carotid disease; in three the disease was more severe on one side and reversal of blood flow in the proximal ipsilateral anterior cerebral artery was demonstrated, consistent with cross flow from the contralateral side via the anterior communicating artery of the Circle of Willis. In the fourth patient augmentation of posterior cerebral artery blood velocities during common carotid compression indicated the major collateral source was from the vertebrobasilar system.

Doppler-shifted ultrasound with spectral analysis was used to assess the internal carotid arteries of 48 patients who had undergone carotid endarterectomy (58 carotid endarterectomies). Three patients died in the immediate post-operative period, therefore 45 patients, who represented 54 endarterectomies, were assessed for up to six years following surgery (mean--thirty-four months). Ultrasound tests demonstrated total occlusion of the internal carotid artery in 7 patients within the first post-operative week. Sonograms from the supraorbital and common carotid arteries exhibit two peaks during cardiac systole (A and B). The post-operative A/B ratios were abnormal in 24 instances and these were associated with symptoms in seven. Of these 24, 7 developed severe disease in the internal carotid artery during the six year follow-up period; five were associated with symptoms. Post-operative A/B ratios were normal in 23 instances, 19 of which remained normal at follow-up. None of these nineteen developed symptoms. Only patients with abnormal post-operative A/B ratios subsequently developed severe occlusive disease in the internal carotid artery during the follow-up assessment. Thirty-eight patients underwent unilateral carotid endarterectomy, eight of whom had severe internal carotid artery disease at the contralateral bifurcation at the time of carotid endarterectomy. A further four patients developed severe occlusive disease in the contralateral internal carotid artery during the follow-up period, one of whom was symptomatic.