Haemodynamic classification of symptomatic obstructive carotid artery disease.

Abstract

63 subjects with symptomatic obstructive carotid artery disease were investigated with transcranial Doppler ultrasonography. Their blood velocities at rest (V) in the middle and posterior cerebral artery (MCA and PCA) and in the extracranial internal carotid artery were measured and the pulsatility index (PI) and Uhem index (VMCA.PIMCA/VPCA.PIPCA) calculated. The vasomotor responses in both MCAs were also tested. The subjects were divided into groups based on the findings on physical examination and cerebral computed tomography. In the patient group with lacunar/territorial infarction we found in the stroke hemisphere: VMCA > VPCA, PIMCA = PIPCA and normal values for the Uhem index and total vasomotor reactivity. In the patient group with watershed infarction this hemisphere was characterized by: VMCA < VPCA, PIMCA < PIPCA and subnormal scores for the Uhem index and total vasomotor reactivity. Displaying features from both stroke groups, we obtained in the hemisphere of interest in patients with transient ischaemic attacks: VMCA = VPCA, PIMCA < PIPCA and normal values for the Uhem index and total vasomotor reactivity. Five patients with clinical evidence of stroke but with negative cerebral computed tomography findings had scores similar to those of the watershed group of patients. For the stroke patients, individual measurements of V, PI and total vasomotor reactivity failed to clearly identify to which stroke group a subject might belong. However, such an identification was achieved in all subjects when using the Uhem index. The Uhem index data in patients with transient ischaemic attacks suggest two subgroups with different pathogenesis underlying, the ischaemic events.