Open surgical repair of thoracoabdominal aneurysms - the Massachusetts General Hospital experience.

Abstract

The modern era of surgical management of thoracoabdominal aneurysms (TAA) began with the pioneering work of E. Stanley Crawford (1); this benchmark series reported an operative mortality of 10% with an incidence of spinal cord ischemia (SCI) of 16%, some 50% of which were total paraplegia. Over a 20 year period until 2006, TAA repair at our institution (2) was predominantly performed using a simplified clamp and sew approach in accordance with Dr. Crawford’s teachings which emphasized operative expediency and technical efficiency (2). Management of TAA during this time was typically performed without use of distal perfusion techniques. Adjunct use included routine cerebrospinal fluid (CSF) drainage (3,4), aggressive intercostal re-implantation (3,5,6), regional hypothermia for spinal cord protection (7,8), infusion of hypothermic renal preservation fluid for prevention of renal failure, and in-line mesenteric shunting (9) to reduce complications resulting from visceral ischemia. Using this approach we achieved favorable results with an overall operative mortality of 8% (6% elective and 13% urgent) with significant SCI in 8% of patients (2). Largely driven by the apparent failure of epidural cooling to drive SCI to less than 5%, we modified operative management of TAA in recent years in an effort to further reduce spinal cord complications. As our experience has shown (10) that patients with type IV TAA can safely be managed with a simplified clamp/sew approach with favorable results, this evolution in operative strategy has been exclusively implemented in management of patients with extents I-III TAA. In essence the rationale exploited the collateral network concept (11-13): we adopted routine use of distal aortic perfusion (DAP) via left atrial to femoral bypass to support the collateral circulation to the spinal cord during the period of aortic cross clamp application. Additionally, intra-operative motor evoked potential (MEP) monitoring (14,15) has afforded the ability to dynamically assess spinal cord ischemia during aneurysm reconstruction. As a result, we have abandoned aggressive intercostal re-implantation in favor of a selective MEP driven re-implantation strategy. Clinical outcomes resulting from this evolution in operative strategy for extents I-III TAA have recently been published and are further highlighted herein (16).