Scenario: This is a bedside ECG strip of lead I and the accompanying arterial waveform in a 24-year-old female trauma patient. She presented 24 hours earlier to the emergency department after an all-terrain vehicle accident in which she sustained multiple injuries to her head, neck, torso, abdomen, and limbs. ECG PUZZLER A regular feature of the American Journal of Critical Care, the ECG Puzzler addresses ECG interpretation for clinical practice. We welcome letters to the Editors regarding this feature.