Transcranial Doppler Monitoring in Angioplasty and Stenting of the Carotid Bifurcation

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Abstract
Purpose: To assess the impact of cerebral embolism and hemodynamic changes during the successive stages of carotid angioplasty and stenting (CAS) using transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA). Methods: In 297 patients (206 men; mean age 69.9±8.0 years), the association of various TCD emboli and velocity variables with procedure-related death and cerebral events (amaurosis fugax, transient ischemic attacks, and stroke) was evaluated. Baseline patient characteristics (age, sex, preoperative cerebral symptoms, and prior carotid endarterectomy) and their associations with procedure-related cerebral events were also assessed. A distinction was made between adverse events that occurred during CAS and those that happened within 7 days. Results: Of the 36 procedure-related retinal and cerebral events, 28 (78%) were encountered intraprocedurally; an additional 6 (2%) events occurred within 7 days after the procedure. Two (0.7%) patients died. At 1 week, the combined minor and major stroke and death rate was 3.7%. Adverse outcome was associated with >4 showers of microemboli at postdilation (odds ratio [OR] 3.2, 95% CI 1.3 to 7.8, p = 0.03), particulate macroemboli (OR 9.1, 95% CI 5.1 to 16.1, p<.001), massive air embolism from ruptured balloons (OR 11.3, 95% CI 7.6 to 16.6, p<0.001), and angioplasty-induced asystole with significant hypotension plus MCA blood flow reduction (OR 3.3, 95% CI 1.4 to 8.3, p = 0.03). Of the patient characteristics, male gender (OR 10.5, 95% CI 1.4 to 75.8, p = 0.02) and preoperative cerebral ischemia (OR 3.3, 95% CI 1.6 to 6.6, p = 0.003) were also related to outcome. Conclusions: In CAS, TCD monitoring provides insight into the pathogenesis of procedure-related cerebral events. Microemboli during poststent dilation, particulate macroembolism, massive air embolism, and angioplasty-induced asystole are associated with adverse outcome, as are male gender and prior cerebral ischemia.