From Beat to Beat: How Electrolytes Shape the Heart's Rhythmic Symphony and Structure

Abstract

Cardiac rhythm is fundamental to cardiovascular health, ensuring synchronized electrical impulses that maintain effective heartbeats and blood circulation. Central to this process are electrolytes—sodium, potassium, calcium, magnesium, and chloride—which regulate the generation and propagation of action potentials across cardiac cell membranes. Each electrolyte plays a distinct role in cardiac electrophysiology: sodium drives rapid depolarization, potassium facilitates repolarization, calcium modulates contraction, magnesium stabilizes ion channels, and chloride maintains ionic balance. Electrolyte imbalances, such as hyperkalemia, hypokalemia, hypernatremia, and hypocalcemia, are critical contributors to arrhythmias, contractility issues, and cardiomyopathies. For instance, hyperkalemia actually depresses the upstroke of the action potential by partially depolarizing the resting membrane (inactivating Na⁺ channels), slowing impulse conduction. Similarly, hypercalcemia shortens action potential duration, while hypocalcemia compromises cardiac contractility. Clinically, maintaining electrolyte homeostasis is critical to mitigating arrhythmic risk and improving outcomes in conditions such as atrial fibrillation and heart failure. Advances in therapeutic interventions, including electrolyte supplementation, ion channel modulators, and precision medicine approaches, offer new opportunities for improving cardiac care. Furthermore, understanding the interplay between electrolytes, myocardial ultrastructure, and systemic comorbidities like hypertension and diabetes is critical for developing targeted therapies. This review highlights the pivotal roles of electrolytes in maintaining cardiac rhythm and provides insights into their clinical and therapeutic implications for managing electrolyte-driven cardiac diseases.