A New Intercostal Artery Management Strategy for Thoracoabdominal Aortic Aneurysm Repair

Abstract

Conclusion: Identification of the anterior spinal artery, artery of Adamkiewicz with magnetic resonance angiography (MRA), and subsequent selective reimplantation of intercostal arteries during open thoracoabdominal aneurysm (TAA) repair may serve as an effective additional adjunct in reducing immediate or delayed paraplegia after repair of TAAs. Summary: Spinal cord ischemia (SCI) before the use of perioperative protective measures occurred in 16% to 31% of patients undergoing TAA repair. Advances in surgical technique, postoperative care, and anesthetic management have been introduced to address the rate of SCI after TAA repair. Intraoperative techniques have contributed to a reduction in the occurrence of SCI with TAA repair. Some have used spinal angiography to identify critical intercostal arteries; however, the technique has proved difficult to use and is associated with some risk. Current advances in computed tomography angiography (CTA) and MRA have made it possible to noninvasively identify important intersegmental arteries in patients undergoing TAA repair. In this article the authors introduce a new adjunct for TAA repair that involves the perioperative identification and selective implantation of critical intercostal arteries based on preoperative MRA imaging. Included in this study were patients undergoing TAA repair from August 2005 to September 2007 at the University of Wisconsin. Spinal artery MRA was used to identify the anterior spinal artery and its major intercostal source preoperatively. Patients received intraoperative spinal cord protection using standard adjuncts. Intercostal arteries felt to be important were preserved or reimplanted as a button after removal of aortic clamps. Perioperative and demographic data were retrospectively collected. MRA of the spinal artery was performed in 27 patients with identification of the anterior spinal artery in 85% of the studies. Open repair was performed in 74% and endovascular repair in 26%. The major intercostal source artery for the anterior spinal artery was preserved or reimplanted in 13 patients (65%) who underwent open repair. In seven patients (35%), there was no attempt to preserve or reimplant any intercostal arteries because the major source artery for the anterior spinal artery was not identified, was diminutive (<1.5 mm in diameter), not accessible, or was associated with significant calcification. In the patients undergoing reimplantation, a mean of 1.67 intercostal arteries were reimplanted (range, 1-3). Of the patients undergoing endovascular repair, the major source intercostal artery for the anterior spinal artery was covered in all cases. No immediate or delayed paraplegia developed in any patient in either group. Comment: The new adjunct here is essentially selective reimplantation of intercostal arteries based on preoperative MRA imaging. It is impossible to know whether this strategy will provide any additional benefit in reducing SCI. In many patients in the open cohort, “important” intercostal arteries were not reimplanted for technical reasons, and all of the patients who underwent endovascular repair and in whom “important” intercostal arteries were identified preoperatively, those arteries were covered during the course of the endovascular repair. No cases of paraplegia were documented in the reimplanted or non-reimplanted patients treated with open repair, or in any of those treated with endovascular repair. The potential utility of this approach is that if you are a selective “reimplanter” of intercostal arteries during TAA repair it is possible, perhaps, with preoperative MRA of the spinal cord circulation, to identify precisely which intercostal arteries to reimplant. Whether this strategy will ultimately result in decreased rates of paraplegia will require a relatively large, multicenter randomized trial and is very unlikely ever to be performed.