Silent cerebral microemboli occurring during carotid angiography: frequency as determined with Doppler sonography.

Abstract

The purpose of this study was to determine the frequency of occult cerebral embolic events during carotid angiography and the relationship of these events to different phases of the procedure.Fifteen patients undergoing carotid angiography were prospectively evaluated by using continuous transcranial Doppler monitoring. Realtime visual and auditory confirmations of emboli were accomplished by recognizing their specific spectral signature and harmonic quality. Specific phases of the examination, such as manipulation of the catheter and guidewire, flushing of the catheter, and injecting contrast material were documented and correlated with embolic occurrences.A total of 1100 embolic phenomena were detected in the middle cerebral artery during carotid angiography. Of these, 944 occurred during catheter flushing and injection of contrast material, and 156 occurred during catheter and wire manipulation. In each patient, more emboli occurred during catheter flushing and injection of contrast material than durin...