We present the case of a patient who came to our attention for enlargement of the cardiac silhouette on chest X-ray. Echocardiography showed moderate diastolic overload of both ventricles with enhanced cardiac output without valvular disease or cardiac shunt that could account for this cardiomegaly. A subsequent abdominal echocardiographic exploration showed an angiomatous transformation of the liver due to diffuse lacunar enlargement of hepatic portal vein branches and arterial-venous shunts. Computed tomography and magnetic resonance imaging confirmed the echocardiographic findings. The imaging findings coupled with cutaneous and nasopharyngeal lesions were suggestive of hereditary hemorrhagic telangiectasia (HHT) and the diagnosis was confirmed after the identification of a mutation in the ACVRL1 gene on chromosome 12. HHT is a rare but underestimated vascular disease that can affect different organs, in particular the liver, leading to organ failure requiring transplantation as occurred in our patient. Echocardiography is a useful imaging tool to exclude cardiac abnormalities as a cause of cardiomegaly and to guide the correct diagnosis of a peripheral origin of high cardiac output.