Usefulness of Transcranial Doppler Monitoring in Stenting for Carotid Stenosis

Abstract

Stenting is an effective treatment for carotid stenotic lesions. However, there have been no devices for the real-time evaluation of the improvement of cerebral blood flow and the detection of ischemic events. We monitored blood flow velocity of the middle cerebral artery (MCA) and embolic signals using transcranial Doppler (TCD) ultrasonography during the stenting procedure.
We studied 14 patients with carotid stenosis treated with stenting. The lesions were located at the common carotid artery (CCA) in 2, the origin of internal carotid artery (ICA) in 8 and intracranial ICA in 4. TCD was seriously monitored to record mean blood flow velocity (MBFV) and pulsatility index (PI), and to detect hyperintensity transient signals (HITS) in the ipsilateral MCA using a probe fixed to a head frame.
Valuable continuous data have been obtained in all cases except for 1 with the trouble of probe fixation. MBFV elevated from 73.9 ± 5.8 to 91.5 ± 6.2 mmHg on average after stenting, and dramatically elevated in 9 cases without blood pressure change. MBFV showed no decrease even in 5 cases with hypotension induced by baroreflex response. We were able to detect intraoperative distal embolism before presenting neurological signs in 1 case. The serial TCD monitoring also clarified the significance of balloon protection by fewer HITS.
TCD was very useful for monitoring the hemodynamic change and distal embolism on stenting.