A Case of High-output Heart Failure Caused by Arteriovenous Fistula Due to Iliac Aneurysm Rupturing Inferior Vena Cava

A 67-year-old male with history of hypertension and diabetes presented with complaining dyspnea on exertion and continuous pain at right lower quadrant. Chest X-ray showed severe pulmonary congestion complicated by bilateral pleural effusion, and blood test revealed elevated brain natriuretic peptide with mild renal dysfunction. Continuous vascular murmur was heard at right lower abdomen. Despite of well-preserved or even hyperkinetic left ventricular systolic function (ejection fraction >60%), moderate pulmonary hypertension, estimated pulmonary pressure: 53 mmHg, was indicated by echocardiography. Therefore, the patient was initially considered as acute heart failure with preserved ejection fraction. However, contrast-enhanced computed tomography identified infrarenal abdominal aortic aneurysm and right common iliac aneurysm 4.8 cm in diameter, which had an arteriovenous fistula (AVF) with inferior vena cava (IVC). Then, we finally diagnosed as having high-output heart failure due to massive AV shunt flow, caused by rupture of arterial aneurysm into IVC. The patient therefore urgently underwent the repair surgery, AVF closure from the arterial side following the repair of the aortic and iliac aneurysms by an artificial Y-shaped vascular graft. After the surgery, pulmonary congestion and pleural effusion quickly diminished, and the patient discharged on the 11^th postoperative day without any postsurgical complication. Although AVF by major arterial aneurysm rupture into vein is not common, it needs to be considered as one of etiologies inducing high-output heart failure.