ECG library
Sinus tachycardia in a febrile infant
intro5 months old· infantA 5-month-old with bronchiolitis, day 3, temperature 38.6, breathing at 58 with retractions. The nurse asks whether the heart rate of 172 is 'an SVT'.
25 mm/s · 10 mm/mV · synthetic tracing
100%
Calipers:2000 ms50.0 small boxes30 bpm if R-RDrag the orange markers. One small box = 40 ms.
Key findings
- Rate under 220 with visible sinus P waves
- Rate that varies and tracks the fever
- Narrow QRS
Learning points
- In an infant, sinus tachycardia rarely exceeds 220 and varies with handling, crying and fever; SVT is usually above 220, fixed, and does not vary.
- Every degree of fever adds about 10 beats per minute; recheck once the antipyretic has worked before calling a rate abnormal.
- The tachycardia that matters is the one with poor perfusion, a quiet child, or no fever to explain it.
Connected