In patients with carotid stenosis, angiography shows the degree of stenosis, but not the arterial pressure distal to the stenosis. The purpose of this study is to determine whether the arterial pressure distal to the stenotic lesion is actually decreased or not.
Sixteen patients with cerebrovascular disorder were studied. Age distribution ranged from 54 to 73 years. There were ten men and six women. Of these patients, ten had cerebral infarction, three had transient ischemic attacks, one had subclavian steal syndrome, one had a small arteriovenous malformation, and one had a giant intracavernous aneurysm. All patients underwent transfemoral catheter angiography and were classified as follows: (1) no definite stenosis, six patients (control group); (2) <50% stenosis, three patients; (3) nearly 50% stenosis, six patients; (4) 90% or more stenosis, two patients.
In these sixteen patients, intraluminal arterial blood pressure measurement (ABPM) was done by using the microcatheter technique. In the control group, mean arterial pressure (MAP) of the internal carotid artery was 95-97% of that of the common carotid artery. We also examined the relationship between MAP distal to the stenosis and degree of stenosis calculated from the angiographical findings. In three patients with <50% stenosis, MAP distal to the stenosis was unchanged as compared with that proximal to the stenosis. On the other hand, in two patients with 90% or more stenosis, distal MAP was significantly reduced. In six lesions of five patients with nearly 50% stenosis, reduction in MAP varied from 5% to 43%. Among these lesions, reduction in MAP was within 10% in three. Significant reduction in MAP was observed in two others. In the remaining one lesion with moderate reduction in MAP (14%), single photon emission CT demonstrated remarkable reduction in cerebral blood flow. In one patient with multiple stenotic lesions, reduction in MAP and flattened pressure wave were observed distal to the stenosis of the petrosal segment. In this patient, however, no reduction in MAP was observed distal to the stenosis of the cervical segment.
From these experiences, it was concluded that ABPM is useful in determining the actual blood pressure distal to the stenotic lesion. This information is quite helpful in deciding the optimal treatment (i.e. medical treatment, bypass surgery, or endarterectomy) for the stenotic lesion of the internal carotid artery.
