14 August, 2017
Complications of Aortic Aneurysm Surgery
An abdominal aortic aneurysm (AAA) is a potentially very dangerous condition that's usually fixed via surgery when the aneurysm is over 5cm (usually detected and measured via ultrasound). Mortality rates for open repair have gotten much better over time, attributable to improved operative techniques and pre- and post-operative management of the patient. There are potential complications of AAA repair in open and endovascular types of procedures. Complications that occur with all surgeries such as deep vein thrombosis (DVT) and bleeding are always a risk, but some complications are much more highly associated with AAA repair than other procedures.
Cardiac complications that can occur include arrhythmias and congestive heart failure, but the most frequent complication is myocardial infarction (average 6.9 percent of the time). This usually is nonfatal and occurs within two days after surgery. The second most common complication is renal failure (about 6 percent); patients with preexisting renal disease are at the highest risk. The possible causes include decreased blood flow to the kidney, clamping the aorta above the renal arteries during repair, and the use of contrast agents that can be toxic to kidney cells. Pneumonia after surgery is also a concern (5 percent), but prophylaxis with early extubation in the ICU and vigorous use of pulmonary toilet techniques can help prevent this. The most serious gastrointestinal complication of open repair is ischemia from lack of blood perfusion to the left colon and rectum. This is usually heralded by an increased IV fluid requirement within 12 hours after surgery and is followed by bloody diarrhea. If other symptoms occur such as fever or increased white blood cell count, the surgeon usually uses sigmoidoscopy to examine the tissue and evaluate whether it can be managed conservatively, or whether further surgery is warranted to remove necrotic tissue. Blood flow to the lower extremities can also be compromised. This is a result of clots or atherosclerotic plaques being dislodged during surgery and embolizing or blocking flow at a smaller downstream artery. This usually warrants surgery and removal of the causative thrombus. This manifests with decreased pedal pulses, along with pain and tenderness in the areas affected. Injury to the spinal cord from lack of blood can also occur, but it's rare unless the repair is being done on an AAA that has already ruptured. Sexual dysfunction is somewhat more common. It's attributable to damage to the autonomic nerves when the surgeon is dissecting, or even due to embolization of thrombi to the smaller arteries to the pelvis. Care taken to preserve the nerves during dissection has been shown to reduce symptoms such as impotence and retrograde ejaculation. Late complications after repair include formations of pseudoaneurysms (3 percent), clotting of the graft (2 percent) and formation of a communicating channel (fistula) between the graft and nearby soft tissue (especially enteric organs).
Endovascular Repair (EVAR)
The most common complications are due to the wound made in the groin to gain access to the femoral artery. These include infection, hematoma (collection of blood) and pseudoaneurysm formation. Endoleak is a common problem. There are different types, but the main problem is persistence of blood flow outside of the graft and through the aneurysm sac. Some of these can be managed conservatively; other types require additional endovascular work such as additional stenting. Device migration is a risk factor for late rupture. When the distance between the cranial part of the device and the lowest renal artery is 5mm or more, device migration by definition has occurred.
Abdominal aortic aneurysm has been treated increasingly better through time as surgical techniques improve. However, one must always be vigilant after surgical intervention. A final word on comparison between the two techniques involves a recent study by the Mayo Clinic--which basically concluded that 30-day mortality and cardiac/pulmonary complications were lower in EVAR as opposed to open repair. However, the trade-off is that graft-related complications were much higher with EVAR. This necessitated further interventions, increased cost and surveillance for the life of the patient.
- Journal of Vascular Surgery. “Graft-related complications after abdominal aortic aneurysm repair: Reassurance from a 36-year population-based experience” Hallett Jr JW, Marshall DM, Petterson TM. 1997; 25:277-284.
- Surgical Clinics of North America. “Approach to the Treatment of Aortic Dissection.” Moon M. Volume 89, Issue 4 (August 2009)
- Sabiston Textbook of Surgery, 18th ed. Townsend 2007
- Stockbyte/Stockbyte/Getty Images