Third-Degree Heart Block: Causes, Symptoms & Severity

Third-degree heart block occurs when impulse signals are not transmitted from the atria (upper heart chamber) to the ventricle (lower heart chamber). This is also referred to as a complete blockage or atrioventricular (AV) block.

Significance

• When third-degree heart failure is diagnosed, the complete blockage decreases the hearts ability to contract causing a loss in function. This condition is severe and can lead to cardiac arrest and/or death.

Causes

• The most common causes of third-degree heart block in adults are from heart disease. It is also caused prior to birth (congenital defect) and/or from complications of the hearts electrical system during heart surgery.

Symptoms

• Fainting, dizziness, fatigue (tired), shortness of breath, chest pain and cardiac arrest are symptoms of third-degree heart block. If these symptoms are present, it is recommended to contact a health care professional or seek immediate medical attention.

Treatment

• Third-degree heart block requires the surgical implant of an artificial pacemaker. Prior to permanence, in an emergency, a temporary pacemaker could be required.

Risk Factors

• The risk factors increase for third-degree heart block to occur in patients with a pre-existing heart condition. These conditions include heart disease, heart attacks, coronary artery disease and cardiomyopathy (weakened heart muscle).