The main symptom of sick sinus syndrome is an abnormal heart rhythm. Initially, this symptom may go unnoticed by patients because there are no other symptoms present. When symptoms are present they may include:
- Low heart rate (bradycardia)
- Fast heart rate (tachycardia)
- Shortness of breath
- Chest pain
- Quickly tiring during physical activity
Causes and Risk Factors
Sick sinus syndrome occurs when the sinus node is not working properly. This can be caused by:
- Sinoatrial block - electrical signals move too slowly through the sinus node, causing an abnormally slow heart rate
- Sinus arrest - the sinus node activity pauses
- Bradycardia-tachycardia syndrome - the heart rate alternates between abnormally slow and fast rhythms, usually with a long pause (asystole) between heartbeats
Sick sinus syndrome can occur at any age. However, the condition often develops slowly over time and is therefore more common in patients 70 years of age or older.
In some cases, sick sinus syndrome can be associated with muscular dystrophy and other diseases that may affect the heart.
Other risk factors include: