Aortocaval and iliac arteriovenous fistulas: recognition and treatment

An arteriovenous fistula is an abnormal connection between an artery and a vein. The main cause of such a fistula involving the abdominal aorta (main trunk of the body's arterial system) or iliac artery (in the groin) is spontaneous rupture of an aneurysm (localized thinning of the artery wall) into the nearby venous system. This complication occurs in only about 1 percent of all aneurysms and 3 to 4 percent of all ruptured aneurysms. Often, the diagnosis of these arteriovenous fistulas is overlooked or delayed, due to the wide range of symptoms they produce. A review was undertaken of 30 years of experience (a total of 20 fistulas) to identify factors that help in making a timely diagnosis. Causes of the fistulas included erosion of the aneurysm (14 cases), injury during spinal surgery (four), and gunshot wound of the abdomen (two). Diagnosis was made from three hours to eight years after occurrence of the fistula. The most common symptom was back pain (70 percent of patients). The most reliable physical finding was the presence of a characteristic bruit (a specific type of sound) in the abdomen; this occurred in 80 percent of the patients. Seven patients (35 percent) had congestive heart failure, and eight had severe leg edema which was confused with venous thrombosis (clots in the leg veins). The average blood loss was 5,960 milliliters; this supports the use of intraoperative autotransfusion (transfusion with the patient's own blood). There were two deaths at surgery (10 percent); both patients had been diagnosed prior to surgery. It is concluded that if recognized and treated appropriately with surgery, these arteriovenous fistulas can be repaired successfully. (Consumer Summary produced by Reliance Medical Information, Inc.)