A 26-Year-Old Man with Palpitations

The patient is a 26-year-old man who presents after 3 days of palpitations. He denies any chest pain, shortness of breath, diaphoresis, fever, or dizziness. He does use home oxygen (2 L/min), but denies any new shortness of breath.
Upon exam, you find:

• General: Alert and oriented X 3
• Lungs: Clear to auscultation bilaterally
• Cardiovascular: Regular and tachycardic without murmur, rub, or gallop
• Abdomen: Soft and nontender without rigidity, rebound, or guarding
• Extremities: No pain or swelling, pulses are 2+ and equal in all 4 extremities

View the ECG and consider what the diagnosis and next steps would be. Resolution of the case is described on the next page.