STENT-GRAFT TREATMENT OF ABDOMINAL AORTIC ANEURYSM (EVAR)
What is EVAR?
The aorta is the largest artery emerging from the heart, it runs from the chest to the abdomen. Its part in the abdomen is called the abdominal aorta. An abdominal aortic aneurysm is an abnormal enlargement of this vessel. Since the aneurysm wall is weaker than the normal vessel wall, enlargement increases over time. The aneurysm may burst after a while under the influence of blood pressure inside. The risk of rupture of the aneurysm is related to the diameter of the aneurysm, and the greater the diameter, the greater the risk. When the explosion occurs, there is serious internal bleeding. This bleeding is often fatal.
Stent-graft treatment, which is an alternative to surgical treatment, is the treatment of aneurysm by inserting a prosthesis called stent-graft into a suitable superficial artery and placing it in the diseased vascular area. The stent-graft is a wire cage covered with a special fabric. A new vessel opening occurs in the vessel where it is placed, the walls of which are formed by the stent-graft.
The procedure is performed in the operating room or in the radiology department of the hospital. Depending on the patient's condition, it is performed by anesthetizing with or without general anesthesia, by preventing the pain sensation with epidural or local anesthesia methods.
The artery called the femoral artery in the inguinal region on both sides is surgically exposed. Catheters loaded with the stent graft to be placed for angiography and for treatment are entered through these vessels and delivered to the appropriate places. Stent-grafts extending to the part where the aneurysm is located and to both main leg veins are placed in an inverted “Y” shape. Catheter systems are withdrawn and the opening in the access vessel is surgically closed. The average process takes 3-6 hours.
If the femoral arteries are so thin that they do not allow the entry of stent-graft catheters, the veins above these veins can be opened and the procedure can be performed. In some cases, a catheter should be inserted into the arm artery. Angiography is performed with this catheter or manipulations to facilitate the procedure. Sometimes, in cases where the patient's vascular structure is not suitable or the procedure needs to be completed more quickly, the stent graft is extended towards one leg and occluded the leg vein on the opposite side. In this case, an artificial vein is surgically placed between the two femoral arteries in the inguinal region to ensure blood supply to the opposite leg. Sometimes aneurysms also occur in the leg veins. In this case, the stent-grafts are extended to eliminate the aneurysm in these vessels.
After the stent-graft is placed and, if necessary, during the procedure, angiography is taken if necessary. In order to ensure that the stent graft is well placed in the vessel and to eliminate leakage from the ends and junctions of the stent-grafts, a special balloon expansion is performed.
The incisions in the groin area are closed with surgical sutures.
After the procedure, the patient is sent to the intensive care unit. Here is a close follow-up. It is necessary to stay in the hospital for about 3 days.
Risks and Complications:
1- Leaks into the aneurysm.
These leaks are caused by the inability of the stent-graft ends to completely close the vessel (type 1), the arteries coming out of the aneurysm sac (type 2), the stent graft junctions added to the end, or the punctured stent-graft opening (type 3) and the pores of the stent graft fabric (type 4). It is possible. These leaks increase the risk of an aneurysm bursting. Especially type 1 and type 3 leaks should be treated early. Type 2 leaks have a low risk of explosion, they can heal spontaneously, and are followed by imaging. Type 4 leaks are very rare, and resolve spontaneously or with re-administration of the medication taken by the patient.
The risk of leakage is 15-25% in the first month.
2- Inflammation may develop in the stent graft (0,2-0,6%)
3- Secondary treatments should be performed in stent graft defects caused by delayed leaks, bending of the stent graft, etc. (30% within 4 years).
4- systemic complications. It develops due to the patient's general medical condition and existing diseases.
Heart: heart failure, infarction (heart attack)
Digestive system: bleeding, intestinal bleeding disorder.
Kidney: Kidney failure.
5- Entry site complications:
a) Due to infection at the incision site; redness, pain, discharge or abscess may occur.
b) Dissection (separation in vessel wall layers)
c) Vascular occlusion or narrowing. Malnutrition may occur that requires treatment through surgery or angiography.
ç) Aneurysm (sac occuring in the weakened area of the vessel wall), pseudoaneurysm (posing that occurs around the vessel due to the inability to close the entrance in the artery), bleeding, nerve damage.
d) Arteriovenous fistula (the formation of a connection between the artery and the vein) may result in malnutrition and swelling in the inserted limb, which requires treatment through surgery or angiography.
e) Because of the previous narrowing in the vessel through which the catheter passes, the catheter causes the flow to be cut off in the vessel.