A Case of Right-Sided Heart Failure and Severe Pulmonary Hypertension Secondary to Partial Anomalous Pulmonary Venous Connection.

Partial anomalous pulmonary venous connection (PAPVC) is a rare congenital anomaly in which one or more pulmonary veins drain into the systemic venous circulation. PAPVC is often misdiagnosed as idiopathic pulmonary hypertension in the adult population. We report a case of a 48-year-old woman with long-standing pulmonary hypertension who presented with recurrent pulmonary oedema and right-sided heart failure. Transthoracic echocardiography showed severe pulmonary hypertension with preserved left ventricular function. Computed tomographic pulmonary angiography excluded pulmonary embolism but confirmed an anomalous drainage of the right upper pulmonary vein into the superior vena cava, consistent with isolated PAPVC without an atrial septal defect. Right heart catheterization confirmed severe precapillary pulmonary hypertension with a positive vasoreactivity response to adenosine. She was successfully managed medically with diltiazem and diuretics, showing sustained clinical improvement. This case highlights isolated PAPVC as a critical, under-recognised cause of severe pulmonary hypertension in adults.