AAA: Endovascular Repair -2
Placement of the endograft requires percutaneous access through both the right and left femoral arteries. Typically the main body of the graft with one limb attached is passed up one iliac artery and into the infrarenal aorta using an 18Fr catheter. The other limb is passed through the left iliac using a 12Fr catheter. The proximal portion of the graft is seated in the infrarenal aorta and the distal limbs are seated in the iliac arteries.
Selection criteria are critical to ensure a good result. The patient’s cardiac, respiratory, and renal status are assessed using standard means. Aneurysm geometry is the primary factor in patient selection. It is best assessed using a high quality, contrast-enhanced spiral CT from the celiac axis to the iliac arteries. From that CT we measure the length of the “proximal aneurysm neck” (the distance below the renal arteries at which the aneurysm starts), the diameter of the aorta at the proximal neck, angulation of the initial portion of the aneurysm, diameter of the iliac arteries, and runoff vessel patency.
Patients who are suitable candidates for AAA endograft insertion are those with relatively straight iliac arteries that are of adequate size to accommodate the endograft (diameter more than 10mm). Satisfactory seating of the proximal endograft requires an adequate “landing zone”. (The infrarenal aorta must be at least 15mm in length, 26mm in diameter, and angulated less than 60 degrees). Adequate runoff vessels are needed to maintain graft limb patency. If these criteria are not met it may not be possible to insert the endograft or the graft may not seat well in the aorta and iliac arteries. Patients who do not meet these criteria may be more satisfactorily repaired using open techniques.
Patients who have mycotic aneurysms, active infections, renal failure, contrast allergy, coagulopathy, limited life expectancy, and aneurysms of both iliac arteries are generally not suitable for endo-AAA repair.
Clearly, less invasive methods for the treatment of AAA are very desirable from the patient’s point of view. If the geometry of the aneurysm and the patient’s physiologic status are suitable, endo-AAA repair is now the preferred means of treatment. Clearly, the overall success of any aneurysm repair method must include minimization of perioperative morbidity and elimination of the risk of aneurysm rupture.
We have been very gratified with the results of aortic endograft surgery. It has been particularly beneficial for patients with other co-morbidities.