Proximal common carotid occlusion

Innominate or proximal common carotid artery stenosis or occlusion is quite often seen on angiograms in symptomatic patients but, unless very severe, does not influence the decision about endarterectomy for any internal carotid artery stenosis. Although it is possible to bypass such lesions, it is highly doubtful whether this reduces the risk of stroke unless, perhaps, several major neck vessels are involved and the patient has low-flow cerebral or ocular symptoms. This very rare situation can be caused by atheroma, Takayasu s disease or aortic dissection. Clearly, close consultation between physicians and vascular surgeons is needed to sort out, on an individual patient basis, what to do for the best. 

Rote et al. (1993, 1994) used a carotid thrombosis model in dogs. A calibrated electromagnetic flow meter was placed on each common carotid artery proximal to both the point of insertion of an intravascular electrode and a mechanical constrictor. The external constrictor was adjusted with a screw until the pulsatile flow pattern decreased by 25 % without altering the mean blood flow. Electrolytic injury to the intimal surface was accomplished with the use of an intravascular electrode composed of a Teflon-insulated silver-coated copper wire connected to the positive pole of a 9-V nickel-cadmium battery in series with a 250000 ohm variable resistor. The cathode was connected to a subcutaneous site. Injury was initiated in the right carotid artery by application of a 150 xA continuous pulse anodal direct current to the intimal surface of the vessel for a maximum duration of 3 h or for 30 min beyond the time of complete vessel occlusion as determined by the blood flow recording. Upon completion of the study on the right carotid, the procedure for induction of vessel wall injury was repeated on the left carotid artery after administration of the test drug. 

The largest study to date involving 109 patients with anterior circulation strokes was recently reported by Copen et al. [27]. All patients had diffusion/perfusion MRl within 24 h of stroke onset, and more than 50% had DWl/MTT mismatch volume of 160% or greater. This mismatch was most common among patients with proximal artery occlusions involving the distal internal carotid artery and/or the proximal middle cerebral artery identified by CTA or MRA. Of particular interest was the observation that there was no difference among patients who were scanned at different times after ictus 69% of patients who were scanned within 9 h had a 160% mismatch, which was very similar to the 68% of patients who were scanned after 9 h. The authors concluded that persistence of mismatch after 9 h is common and occurs most often in patients with proximal occlusions of the anterior circulation. 

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