Q. What's a U wave on an EKG?
A. U waves are seen best in V2 and V3. They should be 1-2mm high and going the same direction as the T wave. Causes include bradycardia and severe hypOkalemia (K<2.7), +/- hypOcalcemia, hypOmagnesemia, hypOthermia, increased intracranial pressure, LVH, HCOM, and some cardiac drugs.
An inverted U wave (opposite deflection to the T wave) suggests CAD, including MI, HTN, valvular disease, congenital heart defect, cardiomyopathy, and/or hyperthyroidism. Source: LITFL
Pro-Tip: The slower the heartrate (<65 bpm), the taller the U wave will be.










