Hyperkalemia Induced Brugada Phenocopy: A Rare ECG Manifestation

Table 1

ECG changes of hyperkalemia depending upon severity with possible mechanism.

Hyperkalemia	Expected ECG finding	Possible mechanism
Mild; (5.5–6.5 mEq/L)	Tall, peaked T waves in precordial leads or; pseudonormalization (i.e., upright) of already inverted T waves such as in LVH	Acceleration of terminal phase of repolarization
Moderate; (6.5–8.0 MEQ/L)	Tall T waves; Prolonged PR interval; Short QT interval; Flattening of P waves; Wide QRS complex	Inactivation of cardiac sodium channels due to decreased atrial and myocardial transmembrane potential resulting in reduced action potential; Atrial tissue is more sensitive so atrial changes in P wave and PR interval are seen earlier than ventricular changes in QRS complex
Severe (>8.0 MEQ/L)	Absent P waves; Conduction defects such as fascicular blocks, bundle branch blocks, complete heart block; Progressively wide QRS complex; Escape beats or rhythm; Eventually “sine wave” morphology; VT, VT, asystole	Suppressed or delayed conduction of SA and AV nodal impulse

LVH: left ventricular hypertrophy; SA: sinoatrial; AV: atrioventricular.