Images in Cardiovascular Medicine Platypnea-Orthodeoxia Syndrome as a Presentation of Hereditary Hemorrhagic Telangiectasia

57-year-old white woman presented with a 3-month history of progressive shortness of breath. Although she attributed her initial subtle symptoms of mild dyspnea as a result of exertion during exercise to “getting older,” she sought evaluation 1 month before presentation because of the onset of a cough productive of purulent sputum. A chest radiograph demonstrated a consolidation in the right lower lobe, prompting treatment for community-acquired pneumonia with oral levofloxacin for 10 days. The patient’s cough resolved, but her shortness of breath relentlessly progressed to symptomatic dyspnea at rest. Dyspnea was exacerbated while upright and improved in the recumbent position. Further history revealed episodes of recurrent epistaxis since childhood, a spontaneous right hemothorax at age 21 during the third trimester of pregnancy, an ischemic stroke at age 25, and hypothyroidism. She has smoked 1 pack of cigarettes per day for the past 30 years and occasionally drinks alcohol. Family history was remarkable for recurrent epistaxis in her brother and son. During examination, oxygen saturation on room air was 83% when upright and 91% lying down. She had clubbing in all fingers (Figure 1), and multiple pinpoint telangiectasias were noted on the tongue (Figure 2) and mucosal surface of the lips. Auscultation revealed normal S1 and S2 without any murmurs, normal breath sounds, and a loud, continuous murmur posteriorly over the left lung base, which intensified with inspiration. Routine laboratory data were unremarkable. Arterial blood gas analysis showed a partial pressure of oxygen of 61 mm Hg, with an inspired oxygen fraction of 44% producing an alveolar-arteriolar gradient of 192. ECG