Pulmonary Hypertension Workup Unraveling a Rare Anomaly in Turner Syndrome.

Turner syndrome (TS) is associated with congenital heart disease, most commonly a bicuspid aortic valve and coarctation of the aorta; however, partial anomalous pulmonary venous return (PAPVR) remains an underrecognized cardiovascular anomaly. PAPVR, in which one or more pulmonary veins drain into the systemic venous circulation, can cause left-to-right shunting, right-sided chamber dilation, and pulmonary hypertension (PH). We report the case of a 51-year-old woman with TS and hypertension who presented with dyspnea and an estimated right ventricular systolic pressure of 55 mmHg on echocardiography. Right heart catheterization (RHC) showed severe PH, with a mean pulmonary artery pressure of 53 mmHg, a pulmonary capillary wedge pressure of 16 mmHg, and a pulmonary vascular resistance of 2.1 Wood units, along with unexpectedly high pulmonary artery oxygen saturations suggestive of a left-to-right shunt. Cardiac MRI demonstrated right-sided enlargement with a pulmonary-to-systemic flow ratio (Qp:Qs) of approximately 3.0 but no intracardiac defect. CT confirmed PAPVR, with the right superior and middle pulmonary veins draining into the superior vena cava and the left superior pulmonary vein draining into the brachiocephalic vein. She improved clinically with tadalafil and furosemide and was referred for surgical evaluation. In patients with TS and unexplained PH, an unexpectedly high pulmonary artery oxygen saturation on RHC should raise suspicion for an occult left-to-right shunt. When no intracardiac defect is identified, multimodality imaging with cardiac MRI and CT can reveal extracardiac shunt lesions such as PAPVR and guide timely referral for definitive management.