A healthy 56-year-old man was in his usual state of health until he developed the abrupt onset of midsternal chest discomfort and epigastric abdominal pain. Thinking this to be indigestion, he took antacids with minimal relief of his symptoms. One day later, he developed acutely worsening shortness of breath, prompting him to call for emergency assistance.

On arrival to the emergency room, his blood pressure was 71/46 mm Hg, pulse was 115 beats per minute, and respiratory rate was 30 breaths per minute. O₂ saturation was 95% on room air. He was in moderate distress. Neck veins were distended. Lung exam demonstrated bibasilar rales. The precordial impulse was hyperdynamic, with a faint 2/6 early systolic murmur heard best in the left lower sternal border. Extremities were cool with no edema. Peripheral pulses were thread (Figs. 38-1, 38-2, 38-3, 38-4, 38-5 and 38-6 and Videos 38-1 to 38-4).