Abstract 12938: A 26 Year Old Male With Exertional Cyanosis
A 26 year old man with a past medical history of asthma presented with a one year course of intermittent exertional cyanosis of his bilateral extremities and lips. General examination was notable for heart rate 90 bpm, blood pressure 130/70 mmHg, and oxygen saturation 85% (room air at rest). He had normal breath sounds and regular heart rate without murmurs, rubs, or gallops. The second heart sound was physiologically split with no marked increase in P2. Extremities demonstrated digital clubbing without edema or cyanosis. Laboratory tests were notable for erythrocytosis (Hgb 18 mg/dL). ECG revealed normal sinus rhythm, normal conduction and normal axis. Prior evaluation included a chest CT with no pulmonary parenchymal disease or thromboembolism. Leading diagnostic considerations included structural heart disease with secondary right to left shunting. Transthoracic echocardiogram showed an atrial septal aneurysm, structurally normal valves and left ventricular EF 65%, with limited visualization of venous inflow. Right heart catheterization demonstrated bidirectional atrial shunting (Qp/Qs 0.26) and normal right sided pressures (RA 12, RVSP 18, PA 19/11 mmHg). The differential diagnosis for an atrial right to left shunt with normal intracardiac pressures included atrial septal defect (ASD) with pulmonary stenosis or Ebstein's anomaly, and the much rarer atrioventricular septal defect (AVSD) with common AV ring - none of these structural abnormalities were noted on echocardiography. However, systemic venous anomalies can also produce right to left shunting and be challenging to image. Cardiac MRI, performed for further shunt evaluation, showed medial displacement of the inferior vena cava, with dynamic, partial shunting of vena caval flow into the left atrium, directed by a prominent Eustachian valve through an ASD (Qp/Qs 0.6). This case highlights an uncommon presentation of hypoxia with an ASD and normal right sided pressures, with the patient's episodic cyanosis attributable to dynamic, effort induced increases in pulmonary arterial pressures and in transatrial shunting. More broadly, it underscores the use of multimodality imaging as guided by clinical history and physical examination to clarify a challenging diagnosis.
- © 2011 by American Heart Association, Inc.