[Aorto-enteric fistulas]

The aorto-enteric fistula (AEF) is a direct communication between aorta and intestinal lumen. There are primary and secondary forms. Primary AEFs are usually due to erosion of an aortic aneurysm (AAA) into the intestine, while secondary forms are caused by reconstructive procedures on the abdominal aorta. The incidence of primary AEF ranges from 0.1 to 0.8%, and secondary from 0.4% to 2.4% [2-4]. The mortality rate after surgical treatment of secondary AEFs is from 14% to 70% [5]. Therefore, they are of great medical importance. The aim of this paper is the presentation of 9 new cases.

Over a 33-year period (1966-1999) a retrospective analysis of patients' records identified 9 patients with AEFs. All were males with average age of 66.62 (51-70) years. In Tables 1 and 2 are presented data on our cases. Of the total number of 9 patients, there were 4 primary and 5 secondary AEFs. All primary fistulas were caused by AAA rupture. Secondary AEFs developed after aortic abdominal surgery in the period between one and seven years after the operation. In 7 cases fistula involved the duodenum, in one the sigmoid and in one the transversal colon. The dominant manifestation of fistulas was gastrointestinal bleeding: melaena--8 (89%); haematemesis and melaena--2 (22%); proctorrhagia--1 (11%). In cases of primary AEFs gastrointestinal bleeding was followed by low back pain and haemorrhagic shok, while in cases of secondary AEFs by sepsis (fever, increased leucocytes count, sedimentation). In two cases the final diagnosis was established by gastrography and colonoscopy, while in two patients Duplex ultrasonographic examination suspected AEF. In all other cases the diagnosis was established intraoperatively (Figure 1). After aneurysmal resection in cases of primary AEFs, revascularization of the lower limbs was performed with extra-anatomic axillo-bifemoral bypass graft (one case) and with "in situ" graft placement (three cases) (Figure 2). The duodenal defect was closed transversally with standard two layers suture techniques in two patients without fistula excision, and in two cases after fistulas excision. In one case associated gastero-entero and entero-entero anastomosis was performed. In all cases with secondary AEFs, after removing of the previously implanted aortic graft, the aorta was closed just below the renal arteries root, and wrapped with a vascularized pedicle of omentum, to separate it from the bowel and the contained area. The duodenal defect was closed after fistulas excision using two layers transversal suture technique in two cases, and in one patient with large fistula a partial duodenectomy and Roux's procedure were necessary. In two patients in whom AEFs involved the transversal and sigmoid colon colostoma was performed. In three cases an extra-anatomic axillo-bifemoral bypass graft was performed for lower limbs revascularization, and in one patient bypass from the ascendent aorta to the femoral artery, using retroperitoneal route was carried out. In one patient the revascularization of the lower limbs was not done because of intraoperative death of the patient.

Seven of our patients died during the first 15 postoperative days. One died during the operation after massive acute myocardial infarction. In other six cases the mortality causes were: MOFS-3 cases, and secondary enteric fistula-3 cases. Two of our patients survived. One has been followed-up for 15 years, and his axillo-bifemoral bypass is patent. The other with bypass from the ascendent aorta to the femoral artery died 7 years after the operation, also with patent graft. More details are given in Table 3.

Sir Astley Cooper was the first who described primary AEFs caused by AAA rupture in 1817 [6], and Brock in 1953, first described secondary AEF developed 6 months after aortic homograft implantation [8]. In 1957, Haberer successfully treated primary AEF by suture of the duodenal defect and aneurysmorrhaphy [9]. In our country Stojanovitsh and Vujadinovitsh in 1966, first treated primary AEF [16]. Their patient died due to MOFS. However, in 1984 and 1985, Lotina successfully treated two patients with secondary AEFs [11] (Figure 3, Sheme 1). The authors also analyzed literature data on the aetiology, pathogenesis, clinical manifestations, diagnosis and treatment of AEFs. In conclusion, the authors suggest: 1. "Omega" extra-anatomic bypass from supraceliac artery trough retroperitonely to femoral arteries; 2. "In situ" replacement of the abdominal aorta using cadaveric homografts; 3. Intraoperative control of bleeding with endoluminal balloon occlusive aortic catheter.