Sinus arrhythmia is a normal variation in which the heart rate speeds up when breathing in and slows when breathing out. It is common and harmless in children and fit young adults, while a form not linked to breathing in older adults may point to heart disease or drug effects.
Key symptoms
- Usually no symptoms; found on a routine exam or ECG
- Some people notice their heartbeat changing speed
- Symptoms are rare and should prompt a search for another cause
What you find on exam
- Pulse speeds up on inspiration and slows on expiration
- Rhythm becomes regular when the patient holds their breath
- Otherwise normal heart exam and vital signs
Tests
- ECG or rhythm strip: normal P wave before every QRS, with P to P intervals that vary
- Variation follows the breathing cycle
- If not linked to breathing or with symptoms: Holter monitor, electrolytes, digoxin level
Treatment basics
- No treatment needed for the breathing-related form
- Reassure and explain that it is normal
- Non-respiratory form: treat the cause and review medications such as digoxin
Red flags
- Fainting or near fainting
- Irregular rhythm that does not follow breathing in an older adult or with heart disease
- Long pauses or a very slow heart rate
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Sources: NCCPA PANCE Content Blueprint; NCSBN 2026 NCLEX-RN Test Plan; NBOME COMLEX-USA clinical presentations. Written by Making Synapses. Making Synapses is not affiliated with these organizations.