Heart Model
Cardiovascular Physiology Concepts Richard E. Klabunde, PhD

Cardiovascular Physiology Concepts 3e textbook cover Cardiovascular Physiology Concepts, 3rd edition textbook, Published by Wolters Kluwer (2021)

CNormal and Abnormal Blood Pressure, Physiology, Pathophysiology and Treatment book cover Normal and Abnormal Blood Pressure, published by Richard E. Klabunde (2013)

Electrocardiogram Leads

As the heart undergoes depolarization and repolarization, electrical currents spread throughout the body because the body acts as a volume conductor. The electrical currents generated by the heart are commonly measured by an array of electrodes placed on the body surface, and the resulting tracing is called an electrocardiogram (ECG, or EKG). By convention, electrodes are placed on each arm and leg (standard and augmented limb leads), and six electrodes are placed at defined locations on the chest (precordial leads). These electrode leads are connected to a device that measures potential differences between selected electrodes to produce the characteristic ECG tracings.

Some ECG leads are bipolar leads (e.g., standard limb leads) that use a single positive and a single negative electrode between which electrical potentials are measured. Unipolar leads (augmented leads and chest leads) have a single positive recording electrode and use a combination of the other electrodes to serve as a composite negative electrode. Normally, when an ECG is recorded, all leads are recorded simultaneously, giving rise to what is called a 12-lead ECG.

Details of the three types of ECG leads can be found by clicking on the following links:

Revised 11/02/2023

Be sure to visit our sister site, CVPharmacology.com.

Why the Ads? CVphysiology.com is very popular with medical school students, physicians, educators, and others. We use the revenue from advertisements to offset the cost of hosting and maintaining this website. Having ads allows us to keep this website free for everyone.

Amazon Badge
Shop for Medical Books & Textbooks on Amazon