Pediatric SVT vs Sinus Tachycardia
Objective: Tell pediatric SVT from sinus tach with P waves, variability, and a reason — then treat the cause or the rate, not a number copied from adults.
Why This Is Hard
Adults get “SVT” (supraventricular tachycardia) stamped on every fast narrow complex. Kids are worse. Sinus rates that would be SVT in a 40-year-old are normal in a febrile infant. Rough cutoffs still help — about 220 in infants and 180 in children — plus the tracing and the story.
Sinus tach has P waves, varies when you stimulate them, and has a reason (fever, pain, dehydration, hypoxia, shock). SVT is usually sudden, regular, no visible P or a retrograde P, and the kid looks “out of proportion” to the fever. Adenosine in sinus tach from sepsis does nothing useful and delays the real work.
- Print or freeze a strip. Hunt for P waves. If the rate wiggles when they cry, that is a hint for sinus.
- Ask for a reason: fever, fluids, work of breathing, blood loss, pain. A reason plus P waves is sinus until proven otherwise.
- Unstable (shock, AMS — altered mental status — collapse from the rate): synchronized cardioversion per protocol — not a debate about milligrams of adenosine.
- Stable SVT: vagal then adenosine only if your protocol says so. Ice for infants is a vagal tool some systems use. Protocol owns it.
Street Sequence
- Protect the airway, breathing, and circulation. Give oxygen if they need it. A hypoxic tachycardic child is a breathing problem first.
- Name rate, regularity, P waves, variability, and the story. Check glucose if they are off.
- If it is sinus, treat the cause (fluid, fever destination, sepsis work). Do not chase the number with adenosine.
- If it is SVT and they are crashing, get pads on and use synchronized cardioversion per protocol. If they are stable, use the protocol vagal and adenosine path, then reassess.
Field Rules
- Rate cutoffs (education, not a law): SVT in infants is often 220 or faster. In children it is often 180 or faster. Overlap exists. The tracing and perfusion win.
- Sinus: P before every QRS, rate changes with stimulation, a physiologic reason. Treat the reason.
- SVT: sudden, very regular, P waves absent or retrograde, rate often stuck. History of “it just started.”
- Unstable is perfusion, not a number: poor tone, mottling, delayed cap refill, AMS, hypotension for age. Electricity per protocol.
- Do not adenosine compensatory sinus tach. You will not fix septic shock with a 6-second pause.
- P waves? Variable rate? A reason?
- Infant about 220 / child about 180 as a clue — not a verdict
- Unstable from the rate — electricity
- Sinus — treat the cause
Field Pitfalls
- Adenosine for a 190 febrile toddler with visible P waves.
- Calling 210 in a screaming infant “definitely SVT” without a strip.
- Delaying cardioversion in a gray, unresponsive SVT to “try meds first.”
- Missing hypoxia as the reason for the rate.
Practice
60-second drill
Partner: 4-month-old, rate 270, gray, barely crying, no P waves on the strip. Then: 4-month-old, rate 180, hot, dry, P waves, screaming. Name the path for each in one sentence.
Related: SVT: Adenosine Framing, Stable vs Unstable Tachycardia, Synchronized Cardioversion.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- AHA/AAP 2025 Pediatric ALS — identify the rhythm and perfusion; protocol owns energy and drug doses
- AHA PALS education pages — sinus vs SVT is a rate-plus-P-wave-plus-story problem
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.