Special Problems in the Endovascular Treatment of the Infrarenal Aorta

Access Vessels

Severe iliac occlusive disease, calcification, and tortuosity can combine to make access for EVAR difficult. Although these challenges can frequently be overcome with adjunctive techniques when only a single anatomic problem is present, the combination of multiple anatomic access issues may make EVAR difficult or impossible to perform. Commercially available endografts are 14 to 20 Fr and thus require a minimum 5- to 7-mm iliac diameter for passage. Although focal areas of iliac occlusive disease can be readily treated to gain access to the aorta, a diffusely diseased iliac artery can be more problematic. Use of longer angioplasty balloons or hydrophilic Coons dilators (over a stiff wire) can sometimes be helpful in these situations. The placement of uncovered stents in the iliac vessel should be avoided before EVAR. Finally, a surgically placed iliofemoral conduit can be considered if the patient is anatomically suitable. Placement of the proximal iliac artery anastomosis typically is performed at the iliac bifurcation, allowing deployment of the ipsilateral endograft limb in the common iliac artery.

An alternate method of obtaining access in a patient with extensive iliac occlusive disease is to create an “internal endoconduit” by placing a covered stent in the external iliac vessel, which is then aggressively angioplastied to the required diameter. The covered stent protects against extensive dissection, free rupture of the native vessel caused by the aggressive angioplasty, or both. There must be a sufficient proximal and distal seal zone for the covered stent for this approach to be safe. Although these techniques have been anecdotally reported with successful outcomes, larger series are needed to establish the safety of this approach.

Significant iliac tortuosity can often be straightened with use of a very stiff guidewire, such as the Lunderquist or Amplatz (Cook Medical, Bloomington, Ind.) guidewires. Severe circumferential calcification in association with tortuosity must be approached cautiously, because even the stiffest guidewire may not straighten the vessel. Rarely, a second “buddy wire” may be helpful in this situation. Superstiff wires should be exchanged for a soft J wire before completion arteriography. Otherwise, an apparent high-grade stenosis may be seen in the external iliac artery that is caused by the vessel “accordioning” on the wire. These pseudolesions disappear with replacement of the stiff wire for a more flexible wire and thus do not require intervention.

“Through and through” access or brachial-femoral access was commonly used in the early period of EVAR to manage tortuous and challenging access vessel anatomy. It is rarely needed today given the development of smaller hydrophilic delivery systems.