Thinking outside the box: a middle-aged man with new-onset dyspnoea on exertion and pedal oedema.

We describe a diagnostic dilemma in a middle-aged man presenting with dyspnoea and bilateral pedal oedema who had been diagnosed with right heart failure based on clinical evidence. The evaluation for aetiology eventually led to discovery of an unusual extrathoracic cause, a left-to-right communication in the renal vasculature. Renal arteriovenous fistulae are rare and can be congenital, acquired or idiopathic. A left-to-right shunt typically presents with high-output cardiac failure involving the left and right sides of the heart. An atypical feature of this case was the finding of overt right heart failure in the setting of a normal left heart. Such a presentation has only been described in a few isolated case reports. Diagnostic approaches include CT angiography and cardiac catheterisation for haemodynamic measurements. The primary treatment options for arteriovenous fistulae are medical management, arterial embolisation and surgical repair. 2015 BMJ Publishing Group Ltd.