Clamping ischemia, threshold ischemia and delayed insertion of the shunt during carotid endarterectomy with patch

Background. Shunt insertion during carotid endarterectomy (CEA) is mandator y to avoid neurological damage due to clamping ischemia; however shunt inse rtion before plaque removal has many inconveniences (atheroembolism, intima l dissection, difficulty of endarterectomy), The aim of this study is to ve rify whether and how long shunt insertion may be safely delayed to permit p laque removal and ensure cerebral perfusion during the further time consumi ng manoeuvres of CEA (peeling, patch angioplasty), Methods. From July 1990 to February 1996 383 patients underwent 411 CEAs un der general anesthesia with EEG continuous monitoring and PTFE patch angiop lasty, A Pruitt-Inahara shunt was routinely inserted only after atheroscler otic plaque removal. In 316 CEAs (76.9%) without EEG signs of cerebral isch emia (Group A) the mean clamping time was 10 min +/-4.8 (range 2-37 min). I n 95 CEAs (23.1%) with EEG signs of cerebral ischemia (Group B) it was 7.3 min +/-3.5 (range 3-20 min). All patients had normal EEG signals after dela yed shunt insertion and reperfusion (mean 21 min, range 5-45 min). Results. In the short term results (within 30 days) there was a relevant ne urological complication rate of 0.96% (2 major stroke and 2 lethal stroke); at awakening we observed 5 RINDs (1.21% of total) 1 in a patient of Group A (0.31%) and the other 4 in patients of Group B (4.21%). Conclusions, These data confirm the rationale of a delayed insertion of the shunt: actually the cerebral parenchyma may tolerate under general anesthe sia a sufferance due to carotid clamping, EEG detectable, without neurologi cal deficits for at least 7.3 min. This time is sufficient to perform the m ost difficult steps of CEA (plaque removal, distal intima checking) allowin g shunt insertion in a clean operatory field, without inconveniences. Final ly the shunt allows complementary time consuming steps, as patch angioplast y, with improvement of both short- and long-term results.