In the ICU, vital signs were BP of 92/58 mm Hg, heart rate of 90 beats/min, respiratory rate of 22 breaths/min, with oxygen saturation of 94% using a 15 L/min nonrebreather mask. Physical examination revealed tachypnea, tachycardia, jugular venous distention, muffled heart sounds, and decreased breath sounds. Arterial blood gas determination showed respiratory alkalosis and marked hypoxemia with a pH of 7.45, Pco2 of 21 mm Hg, and Po2 of 68 mm Hg. Chest radiography showed clear lungs and dilated pulmonary arteries. Electrocardiography demonstrated an incomplete right bundle branch block and evidence of right ventricular (RV) hypertrophy. Urgent transthoracic echocardiography was performed (Video 1).