ECG diagnosis: hypokalemia.

Joel T Levis, MD, PhD, FACEP, FAAEM, is a Senior Emergency Medicine Physician at the Santa Clara Medical Center, and Clinical Instructor of Emergency Medicine (Surgery) at Stanford University. He is the Medical Director for the Foothill College Paramedic Program in Los Altos, CA. E-mail: [email protected]. Figure 1. 12-lead ECG from a 21-year-old man with syncope, generalized weakness, and severe hypokalemia (serum potassium 1.6 mEq/L). Demonstrates prolonged QT interval (649 ms), ST-segment depression, prominent U waves and slurring of the T waves into the U waves (most prominent in lead II).