Descending aortic aneurysm repair utilizing moderate hypothermia (30° C) in conjunction with left heart bypass

Thoracic and thoracoabdominal aortic aneurysm repair are frequently associated with ischemic paraplegia, renal failure and death. In order to decrease the incidence of ischemic events and allow for a longer aortic cross clamp time, we combined our previous technique of segmental sequential repair, left heart bypass and cerebral spinal fluid drainage in conjunction with moderate hypothermia (30°C). Twenty-seven adult patients underwent elective thoracic (n=6) or thoracoabdominal (n=21) aortic aneurysm repair from January 1992 to September 1993 utilizing this hypothermic technique. A heat exchanger was integrated in the centrifugal left heart bypass circuit to achieve moderate hypothermia (30°C) and regain normothermia (37°C) prior to partial bypass termination. Cannulation for left heart bypass was aorta- femoral artery (n=10) or left atrium-femoral artery (n=17). The surgical technique of segmental sequential repair helps to minimize visceral, kidney and spinal cord ischemia. Among these 27 patients, one developed delayed paraplegia on postoperative day 3 and three suffered postoperative death. The average aortic cross clamp time was 76 ± 7 minutes. Previous studies have demonstrated a significant increase of ischemic morbidity (11-25%) when cross clamp times exceeded 30 minutes. We conclude that the combination of left heart bypass, moderate hypothermia and cerebral spinal fluid drainage allow for a longer duration of aortic cross clamp time and a relatively low incidence of ischemic complications.