Moderate hypothermia, with partial bypass and segmental sequential repair for thoracoabdominal aortic aneurysm

Ischemic injury to the spinal cord, kidneys, and viscera occurs in a significant number of patients undergoing surgical repair of thoracoabdominal aortic aneurysms. Partial bypass has been used to perfuse the arterial system distal to the cross-clamp, but the primary determinant of ischemic morbidity remains the duration of aortic cross-clamping. Hypothermia may favorably affect outcome during these procedures, but moderate or deep hypothermia has traditionally required full cardiopulmonary bypass with cardiac arrest.

In a series of patients undergoing thoracoabdominal (n = 14) or thoracic (n = 4) aneurysm repair, we used moderate hypothermia (30 degrees C) and partial bypass (aortofemoral or atriofemoral) while maintaining an intrinsic cardiac rhythm. Body temperature was controlled with a heat exchanger in the bypass circuit, which allowed for rapid cooling and rewarming. In addition to hypothermia and bypass, a segmental sequential surgical repair was used to minimize the duration of ischemia to any given vascular bed.

All patients survived the surgical procedure, and 16 patients survived until discharge from the hospital. None of the 18 patients had paraplegia or significant renal dysfunction. The only complication related to hypothermia was atrial fibrillation, which occurred in three patients and was amenable to therapeutic measures.

We conclude that moderate hypothermia, partial bypass, and segmental sequential repair may reduce ischemic injury. This combination of adjuncts was not associated with significant complications in this series of patients.