You are the attending in the critical care area of a busy ED, and several patients arrive in rapid succession: a confused young man with a scalp laceration who fell off a 10 ft. ladder, a middle aged woman with a suspected femur fracture from an MVC screaming in pain, and a lethargic patient with an alarming LVAD. As you finish your phone call accepting a Level 1 trauma transfer, an RN hands you this EKG:
What's your interpretation of this EKG, and what's on your differential? To whom of the above three patients does this most likely belong?
This EKG belonged to the patient who fell off a 10 ft. ladder and sustained head trauma. In addition to the sinus bradycardia, subtle U-waves can be seen in leads II, III, and V3-V5. U waves are rather nonspecific, and can be present in healthy individuals as well as patients with acute pathology. The differential for the presence of a prominent U-wave includes hypokalemia, hypomagnesemia, hypocalcemia, hypothermia, Class IA and III anti-arrhythmic drugs, digitalis, and acute intracranial pathology . An inverted U-wave in the precordial leads can be a sign of left anterior descending coronary artery occlusion. U-waves are more prominent when patients are bradycardic . In this case, the patient was subsequently diagnosed with a subdural hemorrhage on CT scan.
 Bayés de Luna A, Goldwasser D, Fiol M, Bayés-Genis A. SURFACE ELECTROCARDIOGRAPHY. In: Fuster V, Harrington RA, Narula J, Eapen ZJ. eds.Hurst's The Heart, 14e New York, NY: McGraw-Hill; . http://accessmedicine.mhmedical.com/content.aspx?bookid=2046§ionid=176550544. Accessed January 20, 2018.
Phil Chan, MD (@PhilChanEM)