Aortic Aneurysm Repair Health Article

Definition

Aortic aneurysm repair involves the removal of a dilated (enlarged) portion of the aorta replaced by a woven or knitted Dacron graft to continue uninterrupted blood flow through the aorta and all branch vessels.

Purpose

Aortic aneurysm repair is performed when a portion of the aorta has become dilated as a result of medionecrosis in the ascending aorta or atherosclerosis in the arch and descending segments. Congenital defects in connective tissue are also a risk factor. A history of blunt trauma may be associated with this disease propagation. Prior to 1950, patients exposed to syphilis were at risk of developing aortic aneurysm. Risk of clot formation and rupture of the aneurysm, seen in 50% of cases, as well as dilation to a size greater than 4 in (10 cm) promote repair of the aneurysm by surgical techniques.

Demographics

The patient population for this procedure is typically male with an average age of 65 and a history of medionecrosis or atherosclerosis of the aorta. Patients with a medical history significant for syphilis or blunt trauma are at risk. Congenital defects associated with Marfan syndrome or Ehlers-Danlos syndrome (congenital tissue disorders) need to be monitored.

All patients will be monitored until the aneurysm demonstrates consistent enlargement over time, or grows to greater than 2.2 in (5.5 cm) in diameter at which time surgery is suggested. At a diameter of 4 in (10 cm) surgery is the best option, as risk of rupture increases. Many patients live without symptoms, having the aneurysm identified during other medical procedures.

Description

After general anesthesia is administered, the surgeon will make an incision through the length of the sternum to repair an ascending, arch, or thoracic aortic aneurysm. Abdominal aneurysms are approached through a vertical incision in the abdominal wall. Depending on the location of the aneurysm, cardiopulmonary bypass with deep hypothermic circulatory arrest (arch), cardiopulmonary bypass (ascending), or left heart bypass (thoracic) may be required. All procedures require some amount of anticoagulation, usually heparin, to be administered to prevent blood clot formation. Clamps will be applied across the aorta to prevent blood flow into the aneurysm. The aneurysm will be opened to an area where the tissue is healthy. The healthy tissue will be sutured to a synthetic fiber fabric graft. The fabric is knit or woven Dacron fibers and may be impregnated with collagen, gelatin, or other substances. Blood flow is reinstituted to check for a secure seal. Additional sutures will be added to prevent leaking. The incision is then closed at the completion of the procedure with blood drains penetrating the incision during healing.

Ascending aortic aneurysms may involve the aortic valve or coronary arteries. If the aortic valve is damaged, a graft with an integral aortic valve is used. The coronary arteries are reconnected to the graft.

Aortic arch aneurysms require the reattachment of the arch vessels, the innominate artery, the left common carotid artery, and the left subclavian artery. To decrease surgery time, these three vessels can be treated as a single vessel by using part of the patient's native aorta to create an island. This island is then connected to the graft.

Thoracic aneurysms require special care to protect the spinal vessels that supply blood to the spinal cord. Protecting the spinal cord during repair is still an area of intensive research. Some surgeons feel that rapid implant of the graft to restore blood flow is the best method to protect the spinal cord. A bypass graft called a Gott shunt can be used to redirect the blood flow around the area during surgical repair. Left-heart bypass provides the same benefit as a Gott shunt, with the addition of a mechanical pump for more controlled blood flow to the abdomen and lower extremities.

The abdominal aortic aneurysm is repaired by rapid anastomosis of the graft to return blood flow to the circulation. If the renal arteries are involved in the aneurysm, they will be reattached to the graft. Additionally, if the superior celiac, mesenteric, or inferior celiac arteries are involved, they will also be reattached to the graft. Finally, it is common for the bifurcation (separation into two) of the iliac arteries to be involved; this may require a Y-shaped graft to be used to reattach both lower limb vessels.