Aortocaval Fistula
A fistula between the inferior vena cava and aorta is a rare finding, occurring in 0.2–1.3% of abdominal aortic aneurysms (AAA). The incidence is 1% in asymptomatic and 3–4% in symptomatic aneurysms. Most fistulas occur as a complication of AAA, but 5–10% can occur because of mycotic aneurysms. Ehlers-Danlos and Marfan's syndromes or Takayasu's arteritis can also cause fistulas. Rarely low-velocity penetrating trauma, such as a stab wound, can result in an aortocaval fistula. However, the majority of penetrating injuries to the aorta result in either death or hemodynamic instability necessitating surgical exploration, such that a fistula does not have the opportunity to form. Nevertheless, congestive heart failure in a young patient with a history of trauma should alert the physician to a possible aortocaval fistula.
