We used duplex ultrasonography to evaluate extracranial carotid artery lesion and common carotid blood flow in 249 patients with ischemic cerebrovascular disease. The equipment used was the EUB-415 (Hitachi Medico) with a 7.5 MHz linear type probe with an attached 20°coupler. We investigated the relation between carotid artery stenosis (%Stenosis) and end-diastolic flow velocity (%Dec-Ved) . We also investigated the possibility of differentiating embolic middle cerebral artery (MCA) occlusion from thrombotic MCA occlusion using these two parameters. In order to investigate the relationship between %Stenosis and %Dec-Ved in all the patients studied with and without carotid stenosis, a two-dimensional graph was prepared for each patient plotting %Stenosis on the abscissa and %Dec-Ved on the ordinate. The patients studied were classified into four groups by drawing a line at the 80% carotid stenotic point and another line at the 30% reduction point in the end-diastolic flow velocity. The critical point of reduction in the %Dec-Ved was 80% stenosis of the carotid artery, and the critical point differentiating embolism from thrombosis was 30% decrease in %Dec-Ved. The incidence of carotid atherosclerotic lesions among the patients with cardiogenic cerebral embolism was much lower than that among those with cerebral thrombosis. The end-diastolic flow velocity in the affected common carotid artery was significantly decreased in embolic MCA occlusion, but was not decreased in thrombotic MCA occlusion. In conclusion, we suspect that ultrasonographic classification of patients with ischemic strokes on the basis of %Dec-Ved and %Stenosis is useful in differentiating acute embolic MCA occlusion from thrombotic MCA occlusion and locating the site of vessel occlusion.
We have been studying cerebral blood flow velocity of the bilateral internal carotid and vertebral arteries during each heart beat continuously and simultaneously. This study the calculation of compared the results of the averaged maximum velocity (AMV), which is very time consuming, with those of our new automatic analysis system, which we entitled the averaged maximum spectral density (AMSD) using a dual channel FFT analyzer. AMSD is the arithmetical mean of the maximum value of the power spectrum (MVPS) . MVPS were recorded every 12.5 ms. When the moving averages of 4 MVPS exceed a certain preset value, the heart beat interval record is divided at that point and AMSD is calculated. After the preset value is reached, other divisions are inhibited for a preset duration. The reactivity of the cerebral arteries' velocity of each of 4 healthy males was analyzed before, during and after breath holding. Statistically significant changes occurred in 27 of 33 vessels. Mean values of every 10 seconds of AMV and AMSD showed the highest correlation. It seems that low correlation resulted from weakness of Doppler signals or high audionoise. Even though vertebral blood flow requires careful attention for identification of preset values, we concluded that AMSD is valuable for overall cerebral blood flow monitoring.
The usefulness of Doppler sonography (DS) of the ophthalmic artery (OA) for the investigation of occlusive internal carotid artery (ICA) lesions was discussed and analyzed. [Materials and Methods] Forty-three cases having abnormal findings of the DS of OA were examined by cerebral angiography. Forty-one of the total cases had an occlusive ICA lesion on the angiogram. [Results] 1) The abnormal DS findings were divided into two patterns, consisting of an arch stenosis pattern (SP) in 20 cases and a retrograde pattern (RP) in 23 cases, SP showed ICA stenosis or occlusion with collateral flow through the intracranial vessels. RP showed occlusive ICA lesions with collateral flow through the extracranial vessels. 2) The OA on the angiogram was filled retrogradely in 95% of the RP cases, and was filled normogradely in 55.6% of the SP cases. 3) Twenty-nine cases who received on STA-MCA anastomosis had postoperative improvement in retrograde flow and/or normograde flow and even greater improvement could be seen in the follow-up stage. [Conclusion] DS of the ophthalmic artery is a non-invasive examination and showed good correlation with the angiographical findings of ICA and OA. SAT-MCA anastomosis brought about improvement in retrograde ophthalmic artery flow.