An 81 yr old white female with multiple medical problems presents to the ED complaining only of syncope and weakness; the routine 12-lead EKG is pictured below.
Yet the most remarkable feature of this case is the disarmingly low voltage. Although the electrocardiographic attributes of hyperkalemia remain well exemplified (peaked, sharply pointed T-waves, bradycardia, and a somewhat elongated PR interval), the attention-grabbing mountainous T-waves are conspicuously absent. This is because the EKG must be seen in the context of its own voltage. When viewed against the background of the low-voltage QRS amplitude, the T-waves are proportionally massive, just as in the classic case. Given the considerable incidence of pericardial effusion in pts with renal disease, it is not unreasonable to imagine both of these pathologies contributing to the appearance of this electrocardiogram.
In this case, laboratory assays returned showing a potassium level of 6.4 mEq/L; the pt was temporized in the ED and ultimately admitted for further evaluation. The presence or absence of pericardial effusion could not be confirmed.
Over the past year a variety of superior resources have been released dealing with the problem of critical hyperkalemia, its electrocardiographic manifestations, and its treatment. As it would be a great challenge to improve on what has been done here, I am simply going to replicate the links below.
Link No. 1: Dr. Stephan Smith of Dr. Smith’s ECG Blog has posted a video covering 4 critical hyperkalemia cases with notable EKG presentations. Be sure to take a look at his first case, second EKG, for a valuable signature morphology which can easily be misinterpreted as STE anterior MI.
Link No. 4: Scott Weingart of the EMCrit Podcast has released an incisive 15-minute Pod-Cast covering cutting edge hyperkalemia treatment paradigms. There may be some practice-changing insights here, so check it out.
Link No. 5: Jeffrey Guy of the Surgery ICU Rounds Podcast has a 30-minute overview and discussion of hyperkalemia, normal potassium physiology, and treatment approaches. This is a hospital/ICU-oriented discussion addressing burn medicine, trauma, rhabdomyolysis, etc. More in-depth, more information.
Please feel free to suggest additional resources; also note that the September 2010 case study published here, “Unconscious with Wide Complex Rhythm,” involves a more comprehensive discussion of hyperkalemic EKG changes.