Abdominal aortic aneurysm (AAA) affects an estimated 12 to 15 per 100,000 people a year and causes considerable risk of mortality because of the potential risk of rupture. First introduced in 1991, endovascular aortic aneurysm repair (EVAR) using a stent graft now provides a less invasive alternative to open repair. The procedure has excellent results in appropriately selected patients with good anatomy.
Because aneurysms are often asymptomatic, they are frequently discovered via examination of the abdomen or through an X-ray examination, CT scan or ultrasound study of the abdomen performed for another purpose. If the aneurysm is less than 5 cm in diameter and there are no symptoms, monitoring annually with Doppler ultrasound is recommended. Optimal medical management should include blood pressure control and smoking cessation.
Repair is usually recommended for aneurysms with a diameter of 5 cm or more in women and 5.5 cm or more in men or if there has been growth of more than 0.5 cm in a year. During EVAR, the femoral arteries can be exposed using small incisions, or the procedure may be performed totally percutaneously. Following puncture of the femoral artery, a guide wire is passed across the dilated portion of the aorta, and the stent graft is advanced over the wire. Once the stent graft is correctly positioned, the device is released and the graft expands to exclude the aneurysm just below the renal arteries.
To ensure a proper seal between the stent graft and the aorta, most stents currently available require the aneurysm to have a proximal neck length of at least 1 to 1.5 cm below the renal arteries. However, repair can be done in patients with aneurysms that have shorter necks by using a fenestrated stent graft with side holes and branches to the renal or intestinal arteries. Suitable iliac arteries are required for introduction of the devices, although deployment through a polyester "chimney" graft sutured to the iliac artery via a small retroperitoneal incision has increased the number of candidates for EVAR.
Using a Mayo Clinic aortic registry, Mayo Clinic researchers recently analyzed data from 1,008 consecutive patients (133 women and 875 men) who received endovascular repair between 1997 and 2011:
Most patients treated with EVAR no longer require admission to the intensive care unit and are dismissed home the day after surgery. A higher percentage of patients undergoing EVAR are discharged directly home rather than to nursing homes, and patients have a faster return to normal level of function, with post-discharge recovery time of one to two weeks.
The current prognosis for healthy patients who undergo elective aneurysm repair is excellent. Follow-up imaging studies at regular intervals are required to look for rare late complications such as graft migration or leaks around the stent (endoleaks). If a significant leak around the stent is discovered, the aneurysm sac still can rupture if no procedure to correct this is performed.
However, with low rates of operative and early (30-day) mortality, even among high-risk patients, EVAR represents an exciting and cost-effective advance in the treatment of patients with suitable anatomy.