Atrioventricular block

[Zipporah Schumaker]

Atrioventricular block is a delay in the conduction of electrical current as it passes through the atrioventricular conduction system.
(See also Overview of Abnormal Heart Rhythms and Overview of Heart Block.)
Atrioventricular block is classified as

First-degree: Electrical conduction to the ventricles is delayed
Second-degree: Electrical conduction is intermittently blocked
Third-degree (complete): Electrical conduction is completely blocked

Most types of atrioventricular block are more common among older people. The most common causes are

Fibrous tissue developing in the heart