Sick sinus syndrome

What is sick sinus syndrome?

Sick sinus syndrome occurs when the sinus node — the heart’s normal pacemaker — does not function normally. Sick sinus syndrome is rare in young people except when there is a history of heart surgery involving the heart’s upper chambers — the atria. These operations include the Fontan procedure, Mustard or Senning procedure, repair of total anomalous pulmonary venous connection, and repair of certain atrial septal defects. The incidence of sick sinus syndrome increases over time after these operations.

The heartbeat usually starts in the sinus node, a group of special cells in the upper right atrium. The sinus node speeds up the heart rate when the body is active and slows it down when the body is at rest. In sick sinus syndrome, the sinus node is not able to adjust the heart rate to the level of activity. The sinus node may also fire slowly and/or irregularly and there may be long pauses between beats. This often causes decreased energy levels and low stamina during exercise. The heart rate may also slow down too quickly after exercise causing fainting. The slow, irregular heart rate also increases the risk of abnormal fast heart rhythms called atrial flutter and atrial fibrillation.

What are the effects of this problem on my child's health?

The health effects of sick sinus syndrome vary widely. There may be only mild or no symptoms. The person may have decreased endurance with exercise. If the heart rate is very slow with long pauses, lightheadedness or fainting can occur.

How is this problem diagnosed?

Symptoms: Possible symptoms include low energy levels, low exercise tolerance, lightheadedness, chest pain with exercise, and fainting.

Physical findings: The pulse is slow and often irregular. The physical findings otherwise reflect any underlying heart disease.

Medical tests: One of the first tests usually done is an electrocardiogram. This is a safe and painless test that involves putting some stickers across the chest. The stickers are connected to a machine that records the heart’s electrical activity. Other useful tests include a Holter monitor, echocardiogram, and/or an exercise test. If further information is needed, a special type of heart catheterization called an electrophysiologic study may be done.

How is the problem treated?

If there are symptoms caused by the slow heart rate, repeated episodes of atrial flutter/fibrillation, very slow heart rates, or long pauses between heart beats, a pacemaker may be recommended. Unfortunately, there are no medications that can be used chronically to treat sick sinus syndrome.

What are the long-term health issues for these children?

Overall, the outlook for children and youth with sick sinus syndrome is good. Often the problem causes only mild symptoms. If needed, pacemakers have proven to be effective in treating the symptoms with few changes in lifestyle needed.


Kugler JD: Sinus node dysfunction. In Gillette PC, Garson A Jr. (eds.): Pediatric Arrhythmias: Electrophysiology and Pacing. Philadelphia: WB Saunders Company; 1990:250-300.

Kugler JD, Yabek SM: Sick sinus syndrome: Clinical features and non-invasive evaluation. In Yabek SM, Gillette PC, Kugler JD (eds.): The Sinus Node in Pediatrics. New York: Churchill Livingstone; 1984:48-66.

Yabek SM, Jarmakani JM: Sinus node dysfunction in children, adolescents, and young adults. Pediatrics 1978; 61:593-598.

Written by: S. LeRoy RN, MSN, CPNP

Reviewed September, 2012