CIRCULATORY ARREST UNDER MODERATE SYSTEMIC HYPOTHERMIA AND COLD RETROGRADE CEREBRAL PERFUSION

Background. Profound hypothermia is used for circulatory arrest during cardiovascular operations. Cold retrograde cerebral perfusion enhance s cerebral protection during circulatory arrest. This study examines t he results of circulatory arrest under moderate systemic hypothermia a nd cold retrograde cerebral perfusion. Methods. Circulatory arrest und er moderate systemic hypothermia (nasopharyngeal temperatures of 19 de grees to 28 degrees C, mean of 23 degrees C) and cold (10 degrees C) r etrograde cerebral perfusion were employed in 104 consecutive patients for operation on the proximal aorta (103 patients) or for a venous tu mor invading the heart (1 patient). Aortic operations consisted of rep lacement of the entire transverse arch in 49 patients, hemiarch in 16, ascending aorta in 37, and an extraanatomic aortic bypass in 1. Most patients (83%) also had other procedures such as coronary artery bypas s or an aortic valve operation. Sixteen patients had had previous aort ic operations. The mean circulatory arrest time was 27 minutes (range, 6 to 105 minutes). Results. There were eight in-hospital deaths. Preo perative shock, peripheral vascular disease, and previous aortic opera tions were independent predictors of operative mortality. There were e ight strokes; clinical assessment and computed tomographic scans of th e brain suggested that the strokes were embolic in 6 patients. Atheros clerosis/laminated thrombi in the aorta and the duration of circulator y arrest were independent predictors of stroke. Four patients had seiz ures without neurologic deficit. No patient had development of paraple gia or paraparesis. Conclusions. Systemic hypothermia of 23 degrees C (nasopharyngeal) and cold retrograde cerebral perfusion (10 degrees C) appear to be safe for circulatory arrest times of less than 30 minute s. This strategy of cerebral protection may also be adequate for longe r circulatory arrest times. (Ann Thorac Surg 1998;66:1179-84) (C) 1998 by The Society of Thoracic Surgeons.