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What Is First-Degree Heart Block?

First-degree heart block is a condition that occurs when signals are impaired from the upper (atria) to the lower (ventricle) chambers of the heart. Also known as atrioventricular (AV) block, it does not interfere with blood flow.

  1. Significance

    • This type of heart block decreases impulses through the AV node and causes an increased impulse time frame in the heart chambers. According to the American Heart Association, the impulse from the atria to the ventricles should be less than 0.2 seconds.

    Causes

    • Congenital (acquired at birth) or acquired are causes of first-degree heart block. Heart attack, coronary artery disease, myocarditis (heart muscle inflammation), rheumatic fever and cardiomyopathy (weakening of heart muscle) are common acquired causes.

    Symptoms

    • Generally, no symptoms are present with first-degree heart block. The heart rate and heart rhythm are generally normal and no problems are diagnosed with the heart.

    Treatment

    • Treatment is generally not required for first-degree heart block. A physician will continue to monitor the situation to ensure it doesn't get worse. When it advances to second- and third-degree, medication and/or a pacemaker is required.

    Risk Factors

    • Athletic individuals and heart medications are causes of first-degree heart block. A common medication that causes this condition is Digitalis (digoxin and digitoxin), prescribed to strengthen heart muscle contractions and reduce heart rate.

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