Complications of thoracic aortic endografts: Spinal cord ischemia and stroke

Abstract

Up until the last 5 to 10 years, patients with aneurysms of the thoracic and thoracoabdominal aorta had only one treatment option: open surgical repair. For those patients who could not tolerate operation because of medical comorbidities, continued aneurysm enlargement and eventual rupture was a constant—yet unpredictable—threat to their lives. Several studies have documented improved survival rates in those patients treated surgically. Despite advances in surgical reconstruction and organ protection, the mortality rate for elective repair of thoracoabdominal aortic aneurysms ranges from 4% to 21%; advanced age, renal failure, and postoperative paraplegia are the most important risk factors predicting mortality at 30 days. In addition, for those patients age 79 with an emergency presentation, history of diabetes mellitus, or congestive heart failure, 30-day mortality is 50%. For aneurysms isolated to the descending thoracic aorta, the risk of paraplegia is 0% to 4% and appears to be dependent on the extent of aorta replaced. A substantial number of patients surviving the operation have prolonged, complicated courses secondary to renal, cardiac, and pulmonary dysfunction. Perhaps the most devastating complication of these complex procedures (for patients and their surgeons) is paraplegia. A myriad of techniques have been developed to protect the spinal cord during open surgical repair of the thoracic and thoracoabdominal aorta, including “clamp and sew,” distal aortic and visceral perfusion, complete cardiopulmonary bypass, profound hypothermia and circulatory arrest, direct spinal cord cooling, cerebrospinal fluid (CSF) drainage, and pharmacologic adjuncts; some of these principles may be useful in preventing paraplegia at the time of endovascular repair. When the thoracic aorta is crossclamped, spinal perfusion pressure decreases while CSF pressure increases, resulting in decreased perfusion pressure.