ABC Medical Center > Diseases > Sick Sinus Syndrome

What is sick sinus syndrome?

4 November 2025

Sick sinus syndrome, also known as sinus node dysfunction, is a rare disorder that affects the heart’s rhythm. It damages the sinus node, which is responsible for keeping the heart’s beats steady and regular.

Sick sinus syndrome is characterized by slow, irregular, and paused heartbeats, but episodes of rapid heartbeats can also occur.

Sick sinus syndrome generally appears in people over 50 years old and can arise from various factors, including:

  • Scars from heart surgery or sinus node abnormalities
  • High cholesterol
  • Deterioration of heart tissue due to aging
  • Inflammatory diseases that damage the heart muscle
  • Lack of physical activity
  • Medications used to treat arrhythmias and high blood pressure
  • Neuromuscular pathologies
  • Overweight and obesity
  • Sleep disorders

Sick Sinus Syndrome Symptoms

In this disorder, the sinus node does not function properly, resulting in heart rhythm abnormalities such as bradycardia (a slow heart rate), prolonged pauses between beats, or alternating episodes of slow and fast rhythms, known as tachycardia-bradycardia syndrome. These changes can cause symptoms like fatigue, dizziness, fainting, shortness of breath, or palpitations, especially in older people or those with pre-existing heart conditions.

It is also often related to the degenerative processes of heart tissue due to aging, but it can also be caused by heart diseases, medication side effects, cardiac surgeries, or autoimmune disorders.

Among the most important complications of sick sinus syndrome is an increased risk of falls due to syncope, the onset of heart failure from poor rhythm synchrony, and a greater risk of developing atrial arrhythmias like atrial fibrillation. This can increase the chances of developing blood clots or having a stroke.

Diagnosing Sick Sinus Syndrome

The diagnosis of sick sinus syndrome is based on the correlation between the patient’s symptoms and heart rhythm abnormalities recorded in electrocardiographic studies.

A resting electrocardiogram (ECG) may show sinus pauses, marked sinus bradycardia, or sinus node exit block. However, because these episodes can be intermittent, they may not be detected in a brief evaluation. For this reason, longer studies such as a 24- or 48-hour Holter monitor or event recorders that the patient activates when they have symptoms are often used.

For more complex cases or when the diagnosis is not conclusive, an electrophysiology study can be performed to analyze the heart’s electrical system from the inside, with the help of special catheters.

ECG of a patient with sick sinus syndrome.

It’s important to rule out secondary causes such as medication use or metabolic disorders. Therefore, the diagnostic approach may also include blood tests and a thorough review of the patient’s medical history.

Treating Sick Sinus Syndrome

Treatment for sick sinus syndrome is tailored to the severity of the symptoms and the type of specific heart rhythm abnormalities present.

If the case is mild or the patient is asymptomatic, it may be enough to stop or adjust medications that depress the sinus node function. It is also essential to correct reversible causes, such as metabolic disorders from hypothyroidism or electrolyte imbalances.

However, when symptoms are significant, such as fainting, severe dizziness, or debilitating fatigue, a more definitive approach is required.

The placement of a permanent pacemaker is the most effective treatment for patients with sinus node dysfunction. This device monitors the heart rhythm and sends electrical impulses when it detects that the heart is beating too slowly or stops.

In most cases, dual-chamber pacemakers are used. They coordinate the activity between the atria and ventricles to maintain a physiological rhythm. This intervention not only relieves symptoms but also prevents serious complications such as falls or the progression of arrhythmias to more severe conditions.

At the Arrhythmia Clinic at ABC Medical Center, we can provide you with specialized care. Contact us!

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    Ricardo Ostos

    Ricardo Ostos

    Content Creator

    Ricardo can convey complex medical information in an accessible and friendly way so that all of our patients can understand and benefit from it. In addition, he has an empathetic approach, offering information and practical advice that really makes a difference in people's lives. #lifebringsustogether.

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