Sinus node dysfunction

[Agnes]

Sinus node dysfunction is an abnormality in the natural pacemaker of the heart that causes a slow heart rate.

People may have no symptoms, or they may feel weak or tired or have palpitations.
Electrocardiography is used to make the diagnosis.
A permanent artificial pacemaker is usually needed.

(See also Overview of Abnormal Heart Rhythms.)
Dysfunction of the heart’s natural pacemaker (the sinus or sinoatrial node) may result in a persistently slow heartbeat (sinus bradycardia) or complete cessation of normal pacemaker activity (sinus arrest—see figure Tracing the Heart