Types of slow heart rate, risk of complications, and treatment

There are several types of slow heart rates (bradycardias or bradyarrhythmias). Each type carries a specific risk of complications and treatment options.

Sinus bradycardia

When a person has sinus bradycardia, the heart rate is less than 60 beats per minute. This slow heart rate might be normal. This type of slow heart rate is often seen in healthy, athletic people.

  • Risk of complications? This type is not likely to cause complications, unless the heart rate is very slow (less than 40 beats per minute).
  • Treatment: It rarely requires treatment unless it causes symptoms. Then, a pacemaker may be implanted if there is no underlying cause that can be easily treated.

Sinus pause (also called sinus arrest)

During a sinus pause, the heart may miss one or more beats because its natural pacemaker fails to activate the electrical system throughout the rest of the heart.

  • Risk of complications?Yes, depending on the cause.
  • Treatment: If this occurs often or over an extended period of time, a person may occasionally develop symptoms and need a pacemaker. If there is an underlying cause that is identified, that condition may be treated first.

Atrioventricular (AV) block

  • First-degree block. In first-degree block, the electrical impulses take longer to travel between the upper chamber (atrium) and lower chamber (ventricle) of the heart. This type of heart rhythm may or may not be associated with a slow heart rate.
    • Risk of complications? No.
    • Treatment: It does not usually require treatment. But this type of heart block may raise your risk of heart rhythm problems, such as atrial fibrillation.
  • Second-degree block. In second-degree heart block, some of the electrical impulses are blocked between the upper and lower chamber of the heart. These electrical impulses may or may not have a clear pattern. A second-degree type II block may progress to third-degree heart block.
    • Risk of complications? Yes, especially if it progresses to a third-degree block.
    • Treatment: Second-degree heart block may need treatment with a permanent pacemaker because of the risk that it will progress to a third-degree heart block. A pacemaker also may improve quality of life.
  • Third-degree block. In third-degree heart block, all of the electrical impulses are completely blocked between the upper and lower chambers of the heart.
    • Risk of complications? Yes, the risk is high.
    • Treatment: It almost always requires treatment with a permanent pacemaker.

Tachy-brady syndrome

In tachy-brady syndrome, the heart sometimes beats too quickly (tachy) and sometimes beats too slowly (brady). This abnormal heart rhythm problem is often seen in people who have been diagnosed with atrial fibrillation. It can occur when the heart's natural pacemaker is damaged.

  • Risk of complications? Yes, you may be injured if you faint or have a stroke.
  • Treatment: Tachy-brady syndrome may require treatment with a permanent pacemaker for periods of slow heart rate. If you have a rapid, irregular heart rhythm called atrial fibrillation, you also may need a medicine to slow the heart rate and a blood-thinning medicine.

Last Updated: June 18, 2009

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