What is an endovascular stent graft?
An endovascular stent graft is a tube composed of fabric supported by a metal mesh called a stent. It can be used for a variety of conditions involving the blood vessels, but most commonly is used to reinforce a weak spot in an artery called an aneurysm. Over time, blood pressure and other factors can cause this weak area to bulge like a balloon and it can eventually enlarge and rupture. The stent graft is designed to seal tightly with your artery above and below the aneurysm. The graft is stronger than the weakened artery and it allows your blood to pass through it without pushing on the bulge. Physicians typically use endovascular stent grafting to treat abdominal aortic aneurysms (AAAs), but they also use it to treat thoracic aortic aneurysms (TAAs) and less commonly, aneurysms in other locations.
Aneurysms often affect the aorta, your body’s largest artery. Your aorta carries blood away from the heart and it runs from your heart through your chest and abdomen. The normal diameter of the aorta in the abdomen is about 2 centimeters, which is a little less than 1 inch. An aneurysm is considered to have formed if the aorta grows to more than 1½ to 2 times its normal diameter.
Aortic aneurysms are potentially serious health problems since a burst aorta results in massive internal bleeding that can be fatal unless treated rapidly by an experienced emergency medical team. Endovascular stent graft repair is designed to help prevent an aneurysm from bursting. The term “endovascular” means “inside blood vessels.” To perform endovascular procedures, vascular surgeons use special technologies and instruments. These procedures require only a small incision or puncture in an artery or vein. Through these punctures, a vascular surgeon inserts long thin tubes, called catheters, which carry the devices through your blood vessels to the location of the aneurysm where they can be placed to reline and strengthen your artery. Generally, endovascular treatments allow you to leave the hospital sooner and recover more quickly, with less pain and a lower risk of complications, and sometimes a lower risk of death, than traditional surgery because the incisions are smaller. Sometimes traditional surgery is required, however, if the shape or the location of the aneurysm is not favorable for an endovascular treatment. Your vascular surgeon will help you decide what procedure is best for your particular situation.
How do I prepare?
Your physician will ask you about your medical history and perform a complete physical examination. In addition, your physician may perform several tests, including an electrocardiogram (ECG), which measures your heart’s electrical activity, stress testing, which will help to determine your heart health and a scan to determine if your aneurysm has a favorable shape for endovascular stent graft treatment. If your physician believes that you are a good candidate for endovascular stent grafting, he or she may order one or more of the following tests. These tests show detailed images of your arteries and help your physician choose the correct size and shape of the graft
Spiral computed tomography (CT) scan: This test involves a rapid series of x rays taken in a spiral pattern around your body. A computer transforms the x ray data into three-dimensional images of your blood vessels.
Angiography: In these tests, your physician inserts a catheter into one of your arteries. Your physician then injects a dye called contrast through the catheter and takes x rays.
Am I eligible for endovascular stent grafting?
You may be eligible for elective (non-emergency) endovascular stent grafting if your aortic aneurysm has not ruptured, is large enough (5 centimeters, about 2 inches, wide or more), and you have a long enough area of normal artery for the stent graft to attach securely. Endovascular stent grafting may be a good option if your risk for conventional surgical aneurysm repair is increased because of other illnesses you might have. However, if you have a long life expectancy or have a low risk for complications, or if the shape of the aneurysm is not favorable for an endovascular stent graft, your physician may recommend conventional surgical aneurysm repair instead. To date, this treatment has been used for a longer period of time than endovascular stent grafting and there is general agreement that it requires less long-term maintenance than endovascular repair.
The physical characteristics of your aneurysm help your physician determine if you are a good candidate for endovascular treatment. For example, if you have an AAA located in the section of the aorta just below your kidney arteries, and there is enough space for the stent graft to seal properly, and your aorta is not severely angled, you may be eligible. Your blood vessels also must be large enough to allow the endovascular stent graft to pass through, and the device must fit the shape and contour of your blood vessels once it is in place.
Am I at risk for complications?
If you have kidney disease called chronic renal insufficiency, your chances of complications from endovascular stent grafting may be increased since contrast dye, which can affect the kidneys, is required. If you have an unfavorable aneurysm shape, associated arterial occlusive disease, or have already had an AAA repaired, you also may be at increased risk for complications. Other conditions, such as heart or lung disease, may also increase the risk for treatment. Some of these issues may be addressed by adjunctive measures to lessen the risk of the endovascular procedure if your risk for conventional (open) aneurysm repair is prohibitive. Your vascular surgeon will advise you regarding the best option for your particular situation.
What happens during endovascular stent grafting?
As the procedure begins, you will usually receive a sedative and a regional anesthesia, or you might receive general anesthesia depending upon your particular circumstance. Your vascular surgery team will clean your skin and shave hair around the insertion points to help decrease your chances of infection. Your vascular surgeon will then cut into the skin overlying the femoral artery in your groin. Your vascular surgeon then threads a guide wire into your femoral artery and advances it to the aneurysm. Because you have no nerve endings inside your arteries, you will not feel the wires or catheters as they move through your body. You may feel a slight pressure or a sensation of mild tugging during this insertion.
Using x-rays that appear as moving images on a screen, your vascular surgeon inserts a catheter over the guide wire. Usually your vascular surgeon will perform angiography through the catheter to insure correct placement of the endovascular stent graft. You may feel a warm sensation as the contrast dye is injected. Then, a compressed form of the graft is inserted through a larger catheter, called a sheath, and the guide wire carries so it can move through your blood vessels. When the graft has reached the aneurysm site, your physician withdraws the sheath, leaving the graft in place. The graft expands to fit snugly against the walls of your artery. Often additional components of the graft are placed in a similar fashion through incisions in each groin to extend to the arteries supplying each leg.
