Complications of endovascular aortic repair: prevention and management.

In June 2008, 2 additional endografts were approved for the treatment of thoracic aortic aneurysms in the United States. Their addition to the armamentarium of the aortic specialist allows for the expansion of anatomic criteria in the treatment of patients. Furthermore, additional experience has been obtained in centers of excellence with respect to off-label use of these prostheses. While early complications have been well recognized and documented through rigorous clinical-trial methods,1–3 additional late complications (beyond 1 year) are now being seen. It is important to acknowledge these issues and to develop strategies for the prevention and management of these rare but significant aspects of thoracic endovascular aortic repair (TEVAR). Complications can generally be divided into 2 categories: implantation and postimplantation. The complications encountered during the initial procedure may be related to the device or the procedure. Procedure-related complications, which have been well documented in the pivotal clinical trial publications,1–3 include neurologic, vascular-access, and ischemic problems. Vascular-access problems occur in approximately 15% to 20% of patients, for 2 reasons. Delivery catheters for thoracic devices are rather large (22F–25F), and women, who have smaller arteries, are more strongly represented among patients who have thoracic aneurysms than among patients who have infrarenal aortic aneurysms (male-to-female: thoracic, 60:40; abdominal, 80:20). Therefore, prosthetic conduits or alternative access sites such as the iliac artery or the aorta are needed in as many as 20% of the procedures. Failure to recognize this during case planning can lead to severe complications, including lower-extremity ischemia, increased risk of paraplegia, and death. Neurologic complications comprise both stroke and spinal-cord-related problems. Currently, the risk of stroke appears to be more prominent than spinal-cord-related ischemia and may be associated with the number of manipulations and the location of the disease. Although device coverage of critical, branched great vessels can lead to ischemic stroke, this sequela can be minimized, if not eliminated, by careful preoperative imaging and planning. When the device implantation location extends into treatment zone 0 or 1 (Fig. 1), the risk of stroke increases significantly.2 This may be the result of embolism, because the distribution of the strokes appears in both hemispheres and in the anterior and posterior distributions. Fig. 1 Zones of implantation. Yellow indicates greater risk of stroke. Several studies have analyzed the factors that contribute to spinal cord ischemia,4 which occurs in 3% to 10% of patients in most large series. Identified risk factors include length of coverage of the aorta, prior abdominal aortic surgery, pelvic occlusive disease, perioperative hypotension, and renal failure. Whether left subclavian artery coverage increases the risk is still controversial despite EUROSTAR data suggesting that it does. A recent publication by Feezor and colleagues3 implicated, as factors affecting the risk, not only the extent of treatment but also the location of treatment relative to the distal thoracic aorta. Prevention and management are grounded in traditional techniques, which include the maintenance of spinal cord perfusion pressure and the use of spinal drainage catheters. Although retrograde dissections have been reported as sequelae of the therapy, they fortunately are rare.5 Occurrences of retrograde dissection have been noted in the endovascular repair of all thoracic aortic lesions and with all devices. Whether this sequela is device related or procedure related is difficult to determine, given its low incidence. However, the occurrence of retrograde dissection appears to be higher in the treatment of acute aortic conditions, and in most cases it requires emergent surgical management. Failure of arch conformation (Fig. 2) remains a formidable problem with these devices even after the 2 recent device approvals. It is associated more commonly with nonaneurysmal lesions and with younger patients, who typically have a smaller radius or arch curvature. Failure of conformation can lead to device collapse and to resultant acute aortic obstruction and other sequelae. Device modifications affecting delivery and deployment are currently under clinical investigation; it is to be hoped that these will mitigate, if not eliminate, the problem. Fig. 2 Device malapposition (arrow) to inferior aortic arch wall. During postimplantation follow-up, device collapse is also a possible sequela, as are device migration, endoleak, and prosthesis infection.5 Device migration can be associated with progression of the disease or with patient selection. To ensure minimal long-term complications, the selection of appropriate device-attachment sites is crucial. Endoleaks are not uncommon, and attachment-site problems should be dealt with promptly because they are associated with a high incidence of major complications. Overall, TEVAR has shown excellent results in the clinical trial data. Device use outside the Instructions for Use increases the risk of sequelae associated with the therapy. Certain device and disease complications are rare and typically relate to patient selection and anatomic variations. Device improvements and next-generation devices are under development and are in the early stages of clinical trial, in an effort to mitigate these problems.