What are the typical ECG findings in severe hyperkalemia (high serum potassium levels)?

Updated: Apr 09, 2020
  • Author: Eleanor Lederer, MD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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At a serum potassium level higher than 8.0 mEq/L, the ECG shows absence of P wave, progressive QRS widening, and intraventricular/fascicular/bundle-branch blocks. The progressively widened QRS eventually merges with the T wave, forming a sine wave pattern. Ventricular fibrillation or asystole follows.

The ECG changes of hyperkalemia reverse with appropriate treatment (see the image below).

ECG of patient with pretreatment potassium level o ECG of patient with pretreatment potassium level of 7.8 mEq/L and widened QRS complexes after receiving 1 ampule of calcium chloride. Note narrowing of QRS complexes and reduction of T waves.

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