Sinus Node Dysfunction

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Sinus node dysfunction is historically referred to as sick sinus syndrome. It is due to age-related fibrotic degeneration of the sinus node resulting in impaired signal generation and propagation which manifests as sinus pauses, and occasionally episodes of atrial arrhythmias alternating with bradycardia (tachy-brady syndrome). With tachy-brady syndrome, episodes of bradycardia often alternate with atrial fibrillation.

Examples

ECG Showing Sinus Node Dysfunction

Sinus Node Dysfunction

Atrial fibrillation alternated with sinus arrest and junctional escape in this patient with sick sinus syndrome.
ECG Showing Sinus Node Dysfunction

Sinus Node Dysfunction

Junctional escape alternated with atrial fibrillation in this patient with sick sinus syndrome.

References

  1. Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhyth. Circulation. 2019;140(8):e382-e482.