Unmasking an idiopathic reno-caval fistula: A rare etiology of right-sided high-output heart failure.

An aortocaval fistula is a rare vascular connection between the aorta and inferior vena cava, often caused by abdominal aortic aneurysm, trauma, or infection. It can result in high-output heart failure due to increased venous return and reduced systemic vascular resistance, typically presenting with right-sided symptoms. Renal arteriovenous and reno-caval fistulas are even rarer, with no prior reports of spontaneous idiopathic reno-caval fistulas. A 67-year-old man with hypertension and paroxysmal atrial fibrillation presented with 10 months of generalized edema and exertional dyspnea. He had no history of abdominal trauma or surgery. Examination revealed signs of congestive heart failure and a central abdominal bruit. Echocardiography showed chamber dilation and pulmonary hypertension. Computed tomographic angiography identified a right reno-caval fistula between the right renal artery and inferior vena cava, with associated right renal infarction. The patient underwent successful endovascular embolization using a vascular plug, with gradual resolution of symptoms and improved echocardiographic findings. In cases of high-output heart failure with right-sided symptoms, arteriovenous fistula should be considered, as specific interventions can be highly effective. This rare case underscores the value of a multimodal diagnostic approach combining clinical evaluation and imaging to ensure accurate diagnosis and successful treatment.