Patients with severe pulmonary hypertension (PHT) represent a high-risk population when undergoing noncardiac surgery. During thoracic surgery with 1-lung ventilation, atelectasis of the operative lung, and frequently associated hypoxemia, is likely to exacerbate PHT and precipitate acute right ventricular failure. We present a patient with previously undiagnosed PHT who suffered 2 cardiac arrests during emergent thoracic surgery for empyema. After successful resuscitation in the operating room, she subsequently required prolonged venoarterial extracorporeal membrane oxygenation. Focused transthoracic echocardiography to evaluate cardiac function was critical in the diagnosis of PHT and subsequent treatment with sildenafil and nifedipine when discharged from the hospital.