Open Thoracoabdominal Aortic Aneurysm Repair

Abstract

Thoracoabdominal aortic aneurysms (TAA) comprise 2–5% of all degenerative aortic aneurysms. Open repair carries a 5–10% risk of perioperative morbidity and mortality. The mean rate of growth for these aneurysms is 0.2 cm yearly. Most aneurysms are detected incidentally during radiologic surveillance for other disease processes. Large aneurysms may cause back, epigastric, or flank pain due to compression of local structures. As compared to abdominal aortic aneurysms (AAA), a greater proportion of thoracoabdominal aneurysms are treated urgently. Three-dimensional reconstruction of the thoracic aorta with centerline axis from a dynamic fine-cut, contrast-enhanced CT angiogram is necessary prior to operative intervention. Preoperative cardiac, pulmonary, renal assessment, and optimization is necessary in patients undergoing elective repair. Renal and spinal cord protection using renal hypothermic perfusion of the kidneys with cerebrospinal fluid (CSF) drainage are necessary adjuncts to reduce the incidence of renal complications and incidence of spinal cord ischemia. The continuous exposure of the entire posterolateral aspect of the thoracoabdominal aorta should be obtained with the patient in the right lateral decubitus position. The extent and location of the thoracic portion of the incision are determined by the proximal extent of the aneurysm. The abdominal aorta is exposed in a plane posterior to the spleen, left kidney, and left colon. Circumferential division of the diaphragm through its muscular portion helps in preserving phrenic nerve function. For type I–III TAA, atrial–femoral bypass should be used with continuous perfusion of mesenteric circulation during visceral segment repair. For type IV TAA, the clamp-and-sew technique with adjuncts to reduce warm ischemia time is the best approach. Intercostal artery reconstruction guided by motor-evoked potential (MEP) signals is performed in patients with aneurysmal involvement of the entire thoracic aorta.