What are the cardiac effects and electrocardiogram (EKG) changes that may occur due to hypokalemia?
Cardiac arrhythmias due to hypokalemia include premature atrial and ventricular beats, sinus bradycardia, paroxysmal atrial or junctional tachycardia, arteriovenous (AV) block, and ventricular tachycardia, or fibrillation. Hypokalemia-induced EKG changes include: prolonged QT interval, depression of the ST segment, decreased amplitude of the T wave, and increased amplitude of U waves that occur at the end of the T wave. EKG changes may not correlate well with the degree of hypokalemia, so consideration of continuous telemetry monitoring is warranted in patients with prolonged QT interval, arrhythmias due to hypokalemia, presence of conditions that predispose to arrhythmias (acute myocardial infarction, digitalis toxicity), intravenous (IV) replacement at a rate greater than 10 mEq/h, and patients at risk for rebound hyperkalemia (patients with thyrotoxic periodic paralysis).