Current status of endovascular treatment of aortoenteric fistula

Abstract

Aortoenteric fistula (AEF) is one of the most challenging diagnostic and therapeutic entities in vascular surgery. AEF can occur either primarily involving the aorta and the gastrointestinal tract or, more commonly, secondary to previous aortic reconstructive surgery. Traditionally, the treatment of AEF includes graft excision and extra-anatomic bypass surgery or in situ graft replacement. However, recently endovascular repair has emerged as an alternative therapeutic option. In this article, we present published and current evidence for endovascular repair of primary and secondary AEF. When endovascular treatment is applied where appropriate, early outcomes seem to be superior compared to open surgery. This benefit may be lost during long-term follow-up, implying that a staged approach with early conversion to in situ grafting may realize the best patient survival and morbidity. Lifelong administration of antibiotics is associated with a reduction in re-infection. An endovascular approach used as a bridging procedure in unstable patients is recommended, followed by definitive open therapy, if feasible, in patients with good life expectancy.

Introduction

Aorto-enteric fistula (AEF) is defined as an abnormal connection between the aorta and the gastrointestinal tract. It is the result of either a primary process involving the aorta and the gastrointestinal tract or secondary to aortic interventions after the erosion of an aortic prosthetic graft into the surrounding gastrointestinal structures [1], [2], [3].

In the primary AEF, communication develops between the aorta (commonly aneurysmatic) and the intestinal lumen. This communication most frequently occurs between the infrarenal aorta and the third or fourth portion of the duodenum (in 83% of patients), as these structures are closely related to each other, especially in the presence of an abdominal aortic aneurysm; 20% of the remaining AEFs occur with the small bowel or the colon and 5% with the stomach or a combination of various intestinal sites [1], [2], [4]. In extremely rare cases, primary AEF can develop after endovascular aortic aneurysm repair due to type II endoleak [5].

Secondary AEF occurs after previous open aortic surgery and is the communication between the synthetic graft used for aortic reconstruction and the intestinal lumen [1], [2]. The third portion of the duodenum is the most vulnerable bowel segment to vascular impingement because of its retroperitoneal fixation and proximity to the aorta. The process originates from the ischemia and the subsequent necrosis of the intestinal wall that occurs as a consequence of repetitive traumatic pulsations of the adjacent aortic aneurysm [6], [7]. In more rare cases, secondary AEF can develop after endovascular aortic aneurysm repair [8], [9].

The first description of a primary AEF was published in 1829 by Sir Astley Cooper [10], while the first report of a secondary AEF was published in 1953 by Brock [11], who described a fistula between the proximal anastomosis of an aortic homograft and the duodenum. Zenker [12] performed the first repair of a primary AEF in 1954 by means of a primary closure, and MacKenzie [13] performed the first successful repair of a secondary AEF in 1958.

The prevalence of primary AEF is low, but the diagnosis might be underappreciated; it is estimated that the prevalence is between 0.04% and 0.07% [14], [15]. On the other hand, secondary AEF is more common, with an incidence ranging from 0.77% to 1.6% [16], [17].