In sick sinus syndrome the heart's natural pacemaker fails with age and fibrosis, causing slow rates, pauses or sinus arrest. Many patients also have bursts of atrial fibrillation, a pattern called tachy-brady syndrome.
Key symptoms
- Fatigue and poor exercise tolerance
- Dizziness, near fainting or fainting
- Palpitations from fast episodes
- Confusion or falls in older adults
What you find on exam
- Slow or irregular pulse; may be normal between episodes
- Blood pressure and signs of poor perfusion
- Injuries from falls
- Medication review: beta blockers, diltiazem, verapamil, digoxin
Tests
- ECG: sinus bradycardia, pauses or alternating fast and slow rhythms
- Holter, event monitor or implantable loop recorder to link symptoms to rhythm
- Electrolytes and TSH to rule out reversible causes
- Exercise test if the heart rate fails to rise with effort
Treatment basics
- Stop or reduce drugs that slow the heart when possible
- Permanent pacemaker for symptomatic bradycardia or pauses
- With a pacemaker in place, rate control drugs for fast episodes
- Anticoagulation for atrial fibrillation based on stroke risk
- Unstable bradycardia: atropine, transcutaneous pacing, epinephrine or dopamine infusion
Red flags
- Fainting, especially with injury
- Slow rate with low blood pressure, chest pain or confusion
- Pauses longer than 3 seconds on monitoring
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.