Cardiology I – A Review of Cardiovascular Anatomy and Physiology
by Cwanza A. Pinckney, M.D.

Cardiac Electrophysiology: Electrolytes

Introduction:

The spontaneous generation of cardiac electrical signals, as well as their propagation, is due to alterations in electrolyte concentrations. The major electrolytes that are involved in this process include: Sodium, Calcium, Potassium, Magnesium, and Chloride.

Sodium:

Sodium plays a vital role in automaticity, which is a property characterized by the heart’s ability to generate spontaneous, repetitive contraction stimuli.

Calcium:

Calcium is also essential for automaticity and, in addition, plays a vital role in cardiac contractions.

Potassium:

Potassium’s role in the heart is to reset the repetitive firing system so that it can quickly become active after each electrical stimulus it generates.

Magnesium and Chloride:

The roles of Magnesium and Chloride are unclear, but low levels of these electrolytes impair the replacement and functioning of Sodium, Calcium, and Potassium, thus altering overall heart activity.