Causes and Clinical Manifestations of Sinus Node Dysfunction

In this article, we will discuss various Causes and Clinical Manifestations of Sinus Node Dysfunction. So, let’s get started.


  • Acute MI (inferior wall infarction)
  • Cardiomyopathies
  • Metastatic disease involving the heart (right atrium)
  • Primary muscular dystrophies
  • Amyloid heart disease
  • Tuberculosis involving the heart
  • Degenerative fibrotic disease of atria

Clinical Manifestations

The clinical manifestations of sinus node dysfunction are sinus pauses due to intermittent sinus arrest or sinoatrial exit block. In either case, the ECG manifestation is prolonged pause (>3 sec) of atrial asystole. The symptoms include weakness, fatigue, paroxysmal dizziness or syncope, confusion and congestive heart failure.

In some patients, there may be abnormality both in SA node and AV node conduction (dual nodal disease) hence, there is failure of the AV node to take up the control of rhythm in case the sinus node defaults resulting in periods of ventricular asystole and syncope.

Sick sinus syndrome is a hallmark of sinus node dysfunction, refers to include a combination of symptoms (dizziness, confusion, fatigue, syncope and CHF) and manifested by marked sinus pauses, bradycardia, SA blocks or sinus arrest or bradycardia-tachycardia syndrome on ECG or Holter’s monitoring.

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