Multi-organ failure secondary to an aortocaval fistula-when should it be suspected?

Abstract

Spontaneous aortocaval fistula (ACF) is a rare, life threatening complication of abdominal aortic aneurysms (AAA) which is seldom suspected clinically. We report a case of progressive multi-organ failure secondary to an ACF wherein a delayed diagnosis was followed by a successful outcome. A 67-year-old man presented with dyspnoea on exertion, cough, and night sweats for three weeks. Initial investigations showed type 1 respiratory failure and mild renal impairment. He was treated for a suspected respiratory tract infection and fluid overload but antibiotic and diuretic therapies were ineffective. Within the following 36 hours he developed progressive azotemia and acute liver failure. He had physical signs of predominantly right-sided heart failure with preserved left ventricular systolic function on echocardiogram. Abdominal ultrasound and a non-contrast computed tomography (CT) revealed mild hepatomegaly, a 10 cm AAA with no evident leak and unremarkable kidneys. Oliguria and metabolic acidosis ensued with rapid deterioration of renal function and hypotension necessitating continuous veno-venous hemofiltration with inotropic support. Hepatic and renal function improved within a week of intensive care therapy but signs of volume overload persisted. A contrast abdominal CT demonstrated an ACF, which was successfully managed by endovascular stent-grafting. This case highlights the importance of being alert to the haemodynamic consequences of aortocaval rupture particularly in the presence of a large AAA in a patient presenting with unexplained organ failure and hyperkinetic shock. Optimisation of supportive care impacts favourably on the perioperative course and overall prognosis of this rare condition.