• Disturbances in serum potassium concentration often lead to clinically significant arrhythmias because potassium directly affects automaticity thus increases the risks of asystole, fatal tachyarrhythmias, and PEA (pulseless electrical activity).
• Hypokalemia and hyperkalemia each has distinctive ECG patterns with prominent changes seen in T wave due to potassium’s role in repolarization.
• Hypokalemia manifests as “dip and rise pattern” on ECG:
dip = T wave flattening or inversion with ST depression
rise = prominent U waves
• QT or QU (in case of T-U wave fusion) interval is prolonged hence increases the risks of Torsades de pointes and fatal tachyarrhythmia
• As the severity of hyperkalemia increases, ECG patterns evolve, generally, from developing tall & peaked T waves to prolonged PR intervals, to flattened P waves, to widened QRS complexes, then to sine waves and eventually asystole.
• ECG changes might not correlate exactly with serum potassium concentration (i.e. patients can experience cardiac arrest without prominent ECG changes).
