EKG Challenge No. 18 Case Conclusion: A Nurse Hands You this EKG...

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:  

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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? 

Case conclusion: 

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 [1].  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 [2].  In this case, the patient was subsequently diagnosed with a subdural hemorrhage on CT scan.  

References: 

[1] Cardiol J. 2008;15(5):408-21.

[2] 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&sectionid=176550544. Accessed January 20, 2018.

Phil Chan, MD (@PhilChanEM)