Sick sinus syndrome is a group of heart rhythm disorders that include:

  • Sinus bradycardia: when the natural pacemaker of the heart does not send out a signal telling the heart to beat often enough. The heart beat rate is slow.
  • Sinus pauses or arrest: when the natural pacemaker of the heart stops sending out signals telling to heart to beat for periods of time.

People with these disorders may also have other abnormal heart rhythms, such as:

  • Supraventricular tachycardia: This is a fast heart rate that starts in the upper chambers of the heart (atria).
  • Bradycardia-tachycardia: This is a pattern of alternating slow and fast heart rhythms (sometimes called "tachy-brady syndrome").

 

Symptoms

Most of the time, there are no symptoms. Symptoms that do occur may mimic those of other disorders. They may include:

  • Fatigue
  • Chest pain or angina
  • Confusion or other changes in mental status
  • Fainting or near-fainting
  • Dizziness or light-headedness
  • Sensation of feeling the heart beat (palapitations)
  • Shortness of breath, possibly only with physical activity

 

Causes

Sick sinus syndrome most often occurs in people older than 50. It is often due to scar-like damage to electrical pathways in the heart muscle tissue. In children, heart surgery on the upper chambers is a common cause of sick sinus syndrome.

Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may occur with sick sinus syndrome, although these diseases may have nothing to do with the syndrome.

Sick sinus syndrome is uncommon. Sinus bradycardia occurs more often than the other types of the condition.

Tachycardias that start in the upper chambers of the heart may be part of the syndrome. These include atrial fibrillation, atrial flutter, atrial tachycardia, and other types of fast heart rates. A period of fast heart rates is often followed by very slow heart rates immediately after the tachycardia ends.

Some medicines can make abnormal heart rhythms worse. These include digitalis, calcium channel blockers, beta-blockers, and anti-arrhythmics.

 

Risk Factors

Sick sinus syndrome can occur in people of all ages, even infants. Because it usually develops slowly, over many years, it is most common in people around age 70.

In rare cases, sick sinus syndrome may also be associated with certain conditions such as muscular dystrophy and other diseases that may affect the heart.

 

 Complications

Complications include:

  • Angina
  • Decreased exercise capacity
  • Fainting (syncope)
  • Falls or injury caused by fainting
  • Heart failure
  • Poor heart pumping

 

Prevention

Keeping the heart healthy by eating a well-balanced diet and exercising can prevent many types of heart disease.

It may be necessary to avoid some types of medicines. Many times, the condition is not preventable.