Woman in her 50s with shortness of breath on exertion

Clinical introductionA 59-year-old woman visited an outpatient cardiology clinic due to shortness of breath on exertion. Physical examination showed no significant abnormality of vital signs. A III/VI systolic murmur was heard on the fourth intercostal space at the right sternal border. The majority of laboratory tests were normal. Chest X-ray showed a curved vessel shadow (figure 1A). Initial transthoracic echocardiography showed abnormal blood flow into the inferior vena cava (IVC) in the subxiphoid long axis view (figure 1B) and mild right heart dilatation (online ). Transoesophageal echocardiography showed severe tricuspid regurgitation (online ).[Figure]QuestionWhat is the most likely underlying disease for the patient’s shortness of breath on exertion?Pulmonary arteriovenous fistula.Pulmonary arterial hypertension.Lung cancer.Partial anomalous pulmonary venous connection.Isolated tricuspid regurgitation.