An electrical impulse stimulates the muscle fibers in the heart to contract. The impulse spreads through the heart in a very organized manner, so that the atria contract first, followed by the ventricles.

In first degree heart block, the electrical impulse pauses slightly longer than normal.

Causes for first degree heart block include:

• Heart attack
• Congestive heart failure
• Athletic conditioning
• Myocarditis
• Medications:
• Calcium channel blockers
• Beta blockers
• Digoxin