sick sinus syndrome; atrial fibrillation with bradyarrhythmia; tachycardia-bradycardia syndrome

Etiology

• fibrosis, inflammation or degenerative changes involving the sinoatrial (sinus) node & atria

Epidemiology

• occurs most often in the elderly with underlying heart disease or previous cardiac surgery
• can occur in the fetus, infant, or child without heart disease or other contributing factors, in which case it is considered a congenital disorder

Genetics

• autosomal recessive
• associated with mutations in SCN5A gene (type 1)
• associated with defects in HCN4 (type 2)

Clinical manifestations

• dizziness
• weakness
• palpitations
• syncope or near syncope

Diagnostic procedures

• electrocardiogram
  • sinus bradycardia, sinus arrest, &/or sinoatrial block
  • episodes of atrial tachycardia (including atrial fibrillation) coexisting with sinus bradycardia ('tachy-brady syndrome') are also common

Management

• pharmacologic agents to control supraventricular tachycardia
• consider pacemaker for symptomatic bradycardia or sinus arrest/pause [NGC (NICE)]
• pacemaker implantation may be necessary in order to safely administer medications to control the ventricular response to atrial fibrillation
• minimal pacing of right ventricle may diminishe incidence of atrial fibrillation

More general terms

• supraventricular arrhythmia
• chronic cardiac arrhythmia
• bradyarrhythmia (bradycardia)

Additional terms

• sinoatrial exit block
• sinus arrest/pause
• sinus arrhythmia

Database

• OMIM: https://mirror.omim.org/entry/163800
• OMIM: https://mirror.omim.org/entry/608567