SILENT CEREBRAL MICROEMBOLI OCCURRING DURING CAROTID ANGIOGRAPHY - FREQUENCY AS DETERMINED WITH DOPPLER SONOGRAPHY

OBJECTIVE. The purpose of this study was to determine the frequency of occult cerebral embolic events during carotid angiography and the rel ationship of these events to different phases of the procedure. SUBJEC TS AND METHODS. Fifteen patients undergoing carotid angiography were p rospectively evaluated by using continuous transcranial Doppler monito ring. Real-time visual and auditory confirmations of emboli were accom plished by recognizing their specific spectral signature and harmonic quality. Specific phases of the examination, such as manipulation of t he catheter and guidewire, flushing of the catheter, and injecting con trast material were documented and correlated with embolic occurrences . RESULTS. A total of 1100 embolic phenomena were detected in the midd le cerebral artery during carotid angiography. Of these, 944 occurred during catheter flushing and injection of contrast material, and 156 o ccurred during catheter and wire manipulation. In each patient, more e mboli occurred during catheter flushing and injection of contrast mate rial than during manipulation of the catheter and guidewire. No gross neurologic sequelae occurred. CONCLUSION. Embolic phenomena occur freq uently during all phases of uncomplicated cerebral angiography.