By Eric Choi, MD, and Robert Boova, MD
Patients untreated for thoracoabdominal aortic aneurysm (TAAA) have poor long-term survival, with those ineligible for open or hybrid procedures at high risk of mortality due to aneurysm rupture. Open surgical repair (using a replacement graft), while reliably eliminating the original aneurysm, also has a relatively high rate of operative mortality and other adverse outcomes such as stroke, renal failure and paralysis.1,2 A hybrid approach, using endografting and retrograde visceral revascularization from an iliac artery, allows for staged treatment and avoids clamping of the aorta, but still carries operative risks.3
Due to the important visceral arteries that are often involved in such an aneurysm, endovascular repair of TAAA has historically been difficult, especially when aortic/aneurysmal anatomy precludes the use of fenestrated grafts. Recently, however, physicians have begun to employ parallel stent grafting to solve the problem.
This method uses multiple access points to position a series of parallel endografts alongside a larger aortic trunk endograft, channeling blood into the renal, superior mesenteric (SMA) and/or celiac arteries. The grafts are inserted percutaneously through both femoral and axillary arteries. This modular approach allows up to four (sometimes more) grafts to be positioned simultaneously. The main aortic graft is then opened, followed by the smaller grafts.
Transesophageal ultrasound and CT scans are used to monitor progress and guide treatment planning. For patients with renal issues, the advanced imaging capabilities in Temple’s hybrid operating room allow us to use CO2 as a contrast agent instead of iodine.
Over the past five years, Temple has used the parallel graft technique to treat TAAA patients who were not good candidates for open or hybrid surgical repair. So far we have had 100 percent technical success. Because all grafts must be in place before the first can be expanded, placing more than four grafts is possible only if one of the access vessels is large enough to accommodate insertion of two grafts simultaneously. Post-deployment graft compression and kinking may also occur, although we have largely overcome these issues with the use of smaller, more flexible grafts.
As with any endovascular aortic repair, risks include graft endoleak. Because a greater number of parallel endografts may increase the chance of an endoleak, particular care must be given to allow a sufficient landing zone for each graft. Other risks of this procedure include spinal chord ischemia and access site complications such as bleeding and infection.
When deployed by experienced endovascular practitioners, this parallel graft technique allows patients who are at great risk from both aneurysm rupture and the stresses of open surgery—and who would therefore normally have no options—to receive life-saving treatment.