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Online ISSN 1827-1847
Martinelli O., Trenti E., Stumpo R., Gossetti B., Benedetti-Valentini F.
From the 2nd Chair of Vascular Surgery University “La Sapienza”, Rome, Italy
Background. Intraoperative neurological deficits during the course of carotid surgery are mainly linked to microembolic events, but they can also be caused by cerebral hypoperfusion as a consequence of carotid clamping. Transcranial Doppler (TCD) ultrasonography is currently used to evaluate the risk of cerebral ischemia caused by carotid clamping.
Methods. A total of 508 patients underwent carotid surgery using locoregional anesthesia between January 1991 and December 1998. They were studied using TCD both preoperatively and during the course of surgery. Preoperatively TCD was used to assess the cerebral vasomotor response, the efficiency of communicating arteries, the findings of the compression test on the common carotid artery at the base of the neck. TCD was used intraoperatively to evaluate the changes induced on flow of the medium cerebral artery, homolateral to the test carotid clamping.
Results. The results of TCD were correlated with the number of shunts used and intraoperative neurological deficits observed. This correlation highlighted that: 1) the presence of an activated intracranial collateral circulation or one able to be activated and the vasomotor response are directly correlated with tolerance of carotid clamping in respectively 52 and 70% of cases; 2) the preoperative carotid compression test showed a sensitivity of 63% and 98% specificity; 3) if the mean velocity of the medium cerebral artery during test clamping fell more than 30% below basal values it was an index of a failure to tolerate clamping in 93% of cases.
Conclusions. These results emphasise that TCD is a reliable method for evaluating the risk of cerebral ischemia consequent to carotid clamping preoperatively and, above all, during surgery.
language: English, Italian