An aortocaval fistula is a rare complication of an abdominal aortic aneurysm that requires immediate surgical repair. Doctors can choose to treat it with either open or endovascular surgery.

An aortocaval fistula is a rare condition that occurs when the two largest blood vessels in your body — the aorta and the vena cava — become connected. Aortocaval fistula repair is surgery to fill the hole between your aorta and your vena cava and restore proper blood flow.

Without treatment, an aortocaval fistula can cause life threatening complications. Aortocaval fistula repair can be lifesaving, but it does come with risks and is associated with a relatively high death rate.

This article explains when you might need an aortocaval fistula repair, what happens during the procedure, and what the success rates are.

Your aorta is your largest artery. It carries blood from your heart to the rest of your body. The abdominal aorta is a portion of this blood vessel that supplies blood to your internal organs and lower body.

Your vena cava is your largest vein. It carries blood back to your heart from the rest of your body. The lower part of this vein, the inferior vena cava, runs through your abdomen near your abdominal aorta.

A fistula is a connection between two cavities that are not usually connected. An aortocaval fistula is an irregular connection between your aorta and your vena cava.

An aortocaval fistula is a rare complication of an abdominal aortic aneurysm (AAA), which is a bulging and weakened part of your aorta. If an aortic aneurysm ruptures, it can cause life threatening bleeding.

Experts estimate that aortocaval fistulas occur in less than 1% of AAAs and about 6% of ruptured AAAs.

Less commonly, aortocaval fistulas can be due to:

  • trauma
  • surgical injury
  • disabilities that are present at birth

Symptoms of aortocaval fistula

An aortocaval fistula may not cause symptoms if it’s small. Typical signs and symptoms include:

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An aortic fistula can be life threatening and usually needs treatment with immediate surgery. Doctors may perform surgery with a traditional open approach or an endovascular approach.

Traditional treatment of aortocaval fistulas involves open surgical repair, but there has been a shift toward endovascular repair over the past 20 years. Each technique has pros and cons.

Open surgery

Open surgery involves treating your fistula through a large incision. Before this procedure, you’ll receive general anesthesia to put you to sleep.

Open surgery is more invasive and associated with higher death rates, with reported rates of 16–66%.

Doctors usually perform open surgery if there are anatomical reasons that they can’t perform endovascular surgery.

To avoid constant follow-ups and repeated surgeries, open surgery may also be preferred in younger people without cardiovascular and respiratory complications.

Endovascular repair

Endovascular repair involves inserting a long tube called a catheter into your bloodstream. Doctors often insert the tube through a blood vessel in your groin and use it to place a stent to block blood flow from your aorta to your vena cava.

Your surgical team may perform endovascular repair with local anesthesia. That means they’ll numb the area in your groin where the catheter is inserted, but you’ll be awake during the procedure. But you may need general anesthesia due to the large size of the catheters required.

Compared to open surgery, an endovascular approach is associated with lower early death rates but higher recurrence rates.

Endovascular repair is generally the better option for people who are frail and are not good candidates for open surgery.

General complications of aortic surgery can include:

In a 2023 review of 196 people treated for aortocaval fistulas, researchers found reports of endoleaks in 19 out of 43 people who received endovascular surgery. An endoleak happens when blood leaks around the stent used to repair the hole between the aorta and the vena cava.

One of the main concerns of endovascular surgery is residual aortocaval fistula, meaning that the entire hole isn’t blocked.

Researchers in the same review reported that 2.5% of people who had open surgery and 35.7% of those who had endovascular surgery needed another operation afterward.

Studies looking at the effectiveness of aortocaval fistula repair are uncommon because the condition is so rare. The authors of the same 2023 review found that both endovascular and open surgeries were associated with excellent outcomes. The 30-day survival was 87.5% after open repair and 97.6% after endovascular repair.

Here are some frequently asked questions people have about surgery to repair an aortocaval fistula.

Where is the aortocaval area?

Your aortocaval area is the space between your aorta and your vena cava in the middle of your abdomen. Your aorta and vena cava are your body’s largest artery and vein, respectively.

What is the recovery time for abdominal aortic aneurysm surgery?

It can take weeks to months to fully recover from AAA surgery. Many people feel unusually tired for 4–6 weeks after their procedure. People who have had an open repair may not be able to return to work for 12 weeks or longer.

What is the survival rate for abdominal aortic aneurysm surgery?

The survival rate for AAA surgery depends on whether it’s an elective or emergency procedure. In a 2023 UK study of 980 people who underwent open AAA, the 30-day survival rate was 97.5% for elective surgeries and 70.1% for emergency surgeries. After 2,000 days (about 5.5 years), the survival rates were 43.4% and 25.0%, respectively.

Aortocaval fistula repair as part of AAA surgery is always an emergency procedure.

Aortocaval fistula repair is a surgery to repair an abnormal connection between your aorta and your vena cava. It’s a rare complication of an abdominal aortic aneurysm.

An aortocaval fistula needs prompt treatment to avoid life threatening complications. If diagnosis is delayed, a fistula has a high risk of causing severe bleeding and death.

One of the most common initial symptoms of an aortocaval fistula is sharp and sudden pain in your lower back or abdomen. Call 911 or your local emergency number if you experience this symptom.