The aorta is the main artery in your body. It takes blood from the heart to all the vital organs. It travels through the chest and along the back side of the abdomen, then splits at the level of the umbilicus into the iliac arteries that go to each leg. An aneurysm is a swelling in a blood vessel; it's bigger than it should be. The most common location for an aortic aneurysm is in the abdomen below the artery branches going to the kidneys. On you, this means just below the rib cage and above the umbilicus. The aorta normally measures 2.5cm (1 inch) in diameter in this location. It is called an abdominal aortic aneurysm, or AAA, or "triple A" when it grows to 3cm or greater.
Risk factors for AAA include male sex, age over 65, high blood pressure, family history of aneurysm, and past or present smoking habit (over 100 packs). 5-8% of men over the age of 60 and 30% of men over the age of 80 have aneurysms. Currently the Society of Vascular Surgery supports screening exams for people with multiple risk factors.
We worry about aneurysms because of the risk of rupture. Like a balloon, the larger and larger an aneurysm gets, the greater the risk of rupture. Most people who have a ruptured AAA do not survive, even if they are standing in the hospital when it happens.
Size in diameter is correlated with risk of rupture. We advise fixing AAA in when they reach 5cm in diameter. At 5cm, the risk of rupture is 3-5% yearly; at 6cm, the risk is 12% yearly, and at 7cm, the risk is 25% yearly.
There are 2 ways of fixing aneurysms: open surgery, and stent grafting or endovascular aneurysm repair (EVAR). Which type of surgery is selected is dependent on your age and other medical problems and also the anatomy of the aneurysm.
Open aneurysm repair
Some aneurysms are best fixed with an open approach. Your doctor will discuss this with you. Open surgery involves identifying the aneurysm through an incision down the center of the abdomen. The intestines are shifted to the side, because the aorta sits in the back, on top of the spine. Blood flow is stopped through the aneurysm temporarily with clamps on the vessel above and below, and then the aneurysm is opened longways. A Dacron tube graft is hand sewn into the normal artery above the aneurysm and the normal artery below it. The aneurysm wall is then closed over the top of the graft to protect it. The graft stays in forever and over time, your body forms a lining inside it that looks like the normal artery.
This surgery is performed under a general anesthetic. Sometimes we supplement the anesthetic with an epidural, which can be used afterwards for pain control. The surgery takes 2-3 hours. During surgery, any blood we lose is collected, washed and returned to you. Some people require a blood transfusion. After surgery, you are monitored initially in the ICU. You will have a tube in your nose to remove gastric juices, so that you don't get nauseated. You will have monitoring lines for blood pressure and fluid management. The typical hospital stay is 3-5 days, depending on pain control and how long it takes your intestines to "wake up" following surgery. As with any abdominal surgery, the intestines slow down and become discoordinated (ileus). The ileus is prolonged by narcotics, dehydration, and inactivity. It takes a variable amount of time for the normal peristalsis (gut action) to return, and we cannot feed you until your intestines are working. Flatus (a fart) is the first sign your intestines are ready for food.
Open surgery is considered a more major surgery than EVAR because of the strain on your heart and lungs during surgery. Most often you will undergo preoperative testing to assess your risk for this type of surgery. Potential risks of surgery are the same as for EVAR and include: heart attack, arrhythmia (abnormal heart rhythm), prolonged intubation, pneumonia, kidney failure, infection, stroke, bleeding, or distal embolization.
Endovascular aneurysm repair (EVAR)
Many aneurysms can be fixed with a minimally invasive approach called EVAR, or stent grafting. This surgery involves placing a stent graft (Dacron or Goretex tube supported by metal stents) into the artery to create an internal bypass through the aneurysm. The device is deployed through small cutdown incisions in the groins. The surgeon watches a monitor as she/he manipulates wires and catheters through the arteries. The stent graft is collapsed into a tube which is inserted into the arteries under fluoroscopy (continuous x-ray). When the device is unsheathed it unfurls and the radial force of the metal stent fixes it against the wall of the artery to hold it in place. It is fixed to the normal artery above and below the aneurysm. Blood then flows through the stent graft and does not fill the aneurysm. If there is no blood flow through the aneurysm, the aneurysm does not grow and does not rupture. The blood in the aneurysm sac clots, and over time, the outer wall of the aneurysm sac shrinks down around the graft.
This surgery was initially introduced for people who were too sick to consider open aneurysm repair, but currently, we consider this approach for most people with aneurysms, because there is less up-front risk with this surgery. However, treatment is individualized and some people are not good candidates for EVAR. Your doctor will discuss this with you.
After surgery, we monitor the stent graft with imaging (initially CT scan, later ultrasound), to assess the graft, to check the size of the aneurysm sac, and to ensure there is no endoleak. An endoleak is continued flow into the aneurysm. The most common type is caused by small branch vessels that normally arise from the aneurysm and reverse their direction of flow. In most cases, these vessels seal themselves over time. Rarely, they stay open and are associated with increased growth of the aneurysm. In this circumstance, we perform a secondary procedure to block off (embolize) the branches with metal coils.
For most people, EVAR takes about 2-3hrs. Typically we use a light general anesthetic. Most people do not require blood transfusion, and most people leave the hospital the day following surgery.
Potential risks of surgery include: heart attack, arrhythmia (abnormal heart rhythm), prolonged intubation, pneumonia, kidney failure, infection, stroke, bleeding, or distal embolization. We have performed over 150 EVAR with a complication rate less than 5%.