Surgical Treatment of Abdominal Aortic Aneurysm-Inferior Vena Cava Fistula



Surgical Treatment of Abdominal Aortic Aneurysm–Inferior Vena Cava Fistula



Keith D. Calligaro and Matthew J. Doughterty


A fistula between an abdominal aortic aneurysm (AAA) and the inferior vena cava (IVC) is rare, although many vascular surgeons can expect to encounter at least one or two during their career. The incidence of an aortocaval fistula caused by AAAs is approximately 1% or less but increases to 2% to 4% in the presence of ruptured AAAs. In 1990, we reported that the English-language literature of spontaneous aortic fistula up to that time included 159 patients with aortocaval fistula, 17 with aortorenal vein fistula, and eight with aortoiliac vein fistula who underwent operations. Rupture of an AAA is much more common into the retroperitoneal space or the free peritoneal cavity posterolaterally to the left of the aneurysm, not to the right, where the IVC resides.


A fistula between the aorta and the IVC is actually an erosion of the aorta into the adherent vena cava. The connection between the two usually results from an inflammatory response that exists to varying degrees with all AAAs. A large aneurysm that presses posterolaterally on the IVC is more likely to result in a fistula than a small aneurysm separated by soft tissue. The average diameter of reported AAAs complicated by an aortovenous fistula is 11 cm (range, 4–20 cm), with most being greater than 6 cm in diameter. An understanding of this pathophysiology makes surgical management simpler to comprehend.



Clinical Presentation


Although patients with ruptured AAAs usually have severe hypotension and hypovolemic shock, patients with a fistula alone do not commonly present this way. The rupture of the aneurysm into the vena cava can result in an increased workload and venous return to the heart that can lead to severe tachycardia and possibly congestive heart failure.


A machinery-like abdominal bruit (71% of patients), abdominal or low back pain (83%), pulsatile abdominal mass (89%), and leg swelling along with dilated superficial abdominal veins (58%) are signs of an aortocaval fistula. Hematuria can also be a subtle finding, but it is more likely with a fistula between the aorta and a retroaortic left renal vein. Occasionally the steal of blood is so massive through the fistula into the venous system that acute arterial ischemia of the lower extremities occurs. In addition, thrombus can cover the opening between the two vessels, and the fistula may be unexpectedly encountered at operation without any preoperative hints of its presence.


In elective circumstances, a patent aortocaval fistula can usually be recognized by clinical findings. The diagnosis is confirmed by duplex ultrasonography, computed tomography scan, magnetic resonance imaging, or arteriography.

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Surgical Treatment of Abdominal Aortic Aneurysm-Inferior Vena Cava Fistula

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