Sinus Node Dysfunction
Overview
- Sick sinus syndrome (SSS) occurs when the sinus node is not functioning correctly, due to either intrinsic or extrinsic causes.
Manifestations of Sinus Node Dysfunction
- Sinus bradycardia
- Sinus arrhythmia
- Sinus pause / arrest
- Sinoatrial exit block
- Tachy-brady syndrome
Causes of Sinus Node Dysfunction
Intrinsic
- Idiopathic degeneration
- Myocardial infarction
- Infiltrative disease - sarcoidosis, amyloidosis, haemochromatosis
- Connective tissue disease - SLE, scleroderma, RA
- Cardiac surgery - valvular surgery, correction of congenital heart disease
- Infections - Lyme disease, endocarditis
Extrinsic
- Physiologic - sleep, athletes
- Autonomic - neurocardiogenic syncope, carotid sinus hypersensitivity
- Drugs - beta blockers, calcium channel blockers, digoxin, adenosine, ivabradine, clonidine, acetylcholinesterase inhibitors
- Hypothyroidism
- Hypothermia
- Hyperkalaemia
- Obstructive sleep apnoea
- Raised intracranial pressure
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