Potassium: ECG changes

Advanced, Organ-Based and Clinical Sciences

Earliest change →ST-segment depression, T-wave flattening and inversion, PR interval prolongation along with increase in P-wave amplitude. 

When Serum K < 2 meq/L → U and T waves fuse (giant U waves mask smaller preceding T wave) 

Pseudo-prolonged QT interval → Actually QU interval in absence of T wave. 

Severe hyperkalemia → Tachyarrhythmia (ventricular tachycardia and fibrillation)

                                   → Rare occasions AV block. 

                                   → Can lead to Torsade’s de points 

Hyperkalemia  (see image 3)

Early ECG changes → Peaked T waves

                                 → Short PR interval 

Later changes → Loss of P wave → followed widening of QRS complex → “sine wave” morphology.

null at https://dl.dropboxusercontent.com/s/jp52hk976fi6sd7/Potassium-%20ECG%20changes%201.png

null at https://dl.dropboxusercontent.com/s/u2quvxn2ustnhsw/Potassium-%20ECG%20changes%202.png

null at https://dl.dropboxusercontent.com/s/7cfwyb3db2661r3/Potassium-%20ECG%20changes%203.png


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Ali Kazemi, MD