The Haemodynamic Effect of Carotid Endarterectomy

Abstract

Objectives: to assess the haemodynamic effect of carotid artery surgery, and to relate postoperative changes to the state of cerebral circulation before revascularisation.

Materials and methods: using transcranial Doppler we studied bilateral middle cerebral artery (MCA) flow velocities before and on 1st day, 2nd or 3rd day and 4th or 5th day and 3 months after carotid surgery in 61 patients. In addition, ipsilateral MCA flow velocity was monitored continuously during surgery. Data were related to the internal carotid artery (ICA) perfusion pressure (cerebral perfusion pressure index, CPPI), measured directly before ICA clamping.

Results: postoperatively, MCA flow velocities increased significantly overall (p<0.01), mainly due to pronounced and longer lasting flow velocities in the group of 18 patients with CPPI<0.7 (p<0.05). Flow velocities peaked – absolute as well as relative – on the first postoperative day and then gradually levelled off to reach preoperative values after 4–5 days in patients with high CPPI, whereas MCA flow velocities remained increased in the group of patients with low CPPI. At 3 months flow velocities in both groups were normalised. New neurological symptoms occurred in four patients, who all had low CPPI preoperatively (22% (4/18) vs 0%; Fisher's exact test: p=0.006).

Conclusion: some degree of hyperperfusion was seen in most patients, but the changes were significantly more pronounced in patients with preoperative hypoperfusion, who also suffered significantly more neurological complications.