By W. Michael Park, MD

Medical illustration provided by Marion Tomasko

Endovascular abdominal aortic aneurysm repair (EVAR) was not truly feasible until the current branched graft was developed to allow for implantation across the aortic bifurcation. F-Evar, or fenestrated EVAR, was subsequently developed to address aneurysms that affected the origins of the visceral branch vessels. Currently, branched grafts designed for the aortic arch are also being investigated for thoracic aortic aneurysms encroaching on the arch vessels. So, it may come as a surprise that iliac branched grafts are just now undergoing approval studies.

A closer look

In reality, in terms of priority, the fact that these studies are only now underway becomes more understandable when you look at the numbers.

On one hand, common iliac artery aneurysms occur in conjunction with aortic aneurysms up to one-third of the time. On the other, isolated common iliac artery aneurysms are relatively rare. With traditional bypass, the iliac aneurysm is excluded and the distal end of the bypass is usually performed at the iliac bifurcation, preserving flow to the internal and external iliac arteries.

With EVAR, several approaches are taken. When an iliac aneurysm is relatively moderate in size, the stent graft is ended in a flared bell bottom, usually with an aortic cuff. When a good seal is not possible because the iliac aneurysm is too large, the internal iliac artery is commonly sacrificed by coil embolization and the stent graft is extended into the external iliac.

While it has been known that EVAR was risky for buttock or colorectal necrosis (and death) when done bilaterally, it was initially believed to be relatively benign for the patient when done on one side at a time. Now, however, we know that even for unilateral hypogastric occlusion there is a 20 to 50 percent chance of ipsilateral buttock claudication and a 10 to 20 percent chance of impotence.

Innovative, new graft designs

Hybrid procedures are sometimes undertaken to send a short bypass to the internal iliac artery after a stent graft is extended into the external iliac artery (See figure). Sandwich procedures that use two stent grafts deployed into the common iliac artery limb have been tried with modest success. Experiences with surgeon-modified devices have also been published. The better method, I believe, is to design a graft specifically to the branch.

Here at Cleveland Clinic, where many of the techniques to treat common iliac artery aneurysms were pioneered, we are participating in two FDA-approval trials to investigate two such devices. The Gore Iliac Branch Endoprosthesis (IBE) Trial and the Cook Branched Endograft Trial both offer endovascular solutions for common iliac aneurysms.

These trials, which are currently enrolling patients, offer the latest in technology, potentially providing a minimally invasive solution based on established design principles. To refer a patient for either of these trials, contact W. Michael Park, MD, (216.444.6268, parkm3@ccf.org) and Matthew Eagleton, MD, (216.445.1167, eagletm@ccf.org).