Neonatal Supraventricular Tachycardia
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Neonatal cardiology · Grand rounds
2026

Neonatal Supraventricular Tachycardia

Recognition, acute management and long-term outcome in the newborn
Presented by
Dr. Amr Alashmawy
Overview

How this talk is built

From recognising the arrhythmia, through its mechanisms, to what you do at the cot side.

FOUNDATIONS

  1. 01Clinical problem
  2. 02Definition
  3. 03Epidemiology

MECHANISM

  1. 04Types of SVT
  2. 05Causes

DIAGNOSIS

  1. 06ECG recognition
  2. 07Sinus tach vs SVT
  3. 08Presentation

ACTION

  1. 09Management
  2. 10Drugs to avoid
  3. 11Post-conversion
  4. 12Long-term therapy
  5. 13Prognosis
  6. 14Key messages
Neonatal Supraventricular Tachycardia01
01
Section 01

The Clinical Problem

Why neonatal SVT demands immediate recognition
Section 01 · The clinical problem

Recognition is time-critical

Neonatal SVT is the most common sustained tachyarrhythmia in newborns and young infants.
Although many infants appear well initially, prolonged episodes can rapidly progress.
Heart failure
Cardiogenic shock
Tachycardia-induced cardiomyopathy
Early recognition and treatment are essential.
Neonatal Supraventricular Tachycardia02
02
Section 02

Definition & Recognition

What SVT is, and how it declares itself
Section 02 · Definition

What counts as supraventricular

SVT is a tachyarrhythmia originating above the bundle of His that produces a rapid heart rate.
Three possible origins
  • Atria
  • AV node
  • Accessory pathways
RALARVLVSA nodeAV nodeBundle of HisBundle branchesPurkinje fibres
The cardiac conduction system
Neonatal Supraventricular Tachycardia03
Section 02 · Recognition

Diagnostic characteristics

Heart rate
220–300
beats / minute
Rhythm
Regular
no beat-to-beat variation
Behaviour
Abrupt
onset and termination
Morphology
Narrow
QRS complexes (usually)
P waves
Absent
hidden or retrograde P waves
Fixed RR interval · sudden onset · sudden termination — the triad that separates SVT from sinus tachycardia.
Neonatal Supraventricular Tachycardia04
Clinical pearl

In a neonate, a heart rate >220 bpm is SVT until proven otherwise.

Threshold
Sinus tachycardia · rarely exceeds 220 bpm
SVT · 220–300 bpm
100140180220260300
Neonatal Supraventricular Tachycardia05
03
Section 03

Epidemiology

How often, and when, it presents
Section 03 · Epidemiology

How common is it?

Incidence
1–4
per 1,000 live births
Prevalence
0.1–0.4%
of all newborns
Sex
~60%
male predominance
Most common age
Days–weeks
of life at presentation
The most common arrhythmia requiring treatment in infancy.
Neonatal Supraventricular Tachycardia06
Section 03 · Epidemiology

Two peaks of presentation

Birth
Peak 1
24–48 hours
First presentation window
Peak 2
1–2 months
Second presentation window
Most infants present in the first days to weeks of life.
Neonatal Supraventricular Tachycardia07
04
Section 04

Types of Neonatal SVT

Five mechanisms, one presentation
Section 04 · Types

Five mechanisms, ranked by frequency

Reported frequency ranges in neonatal SVT. Bar length is proportional to the midpoint of each range.
AVRT
Atrioventricular re-entrant tachycardia
60–70%
AT
Atrial tachycardia
15–25%
AVNRT
AV nodal re-entrant tachycardia
10–15%
JET
Junctional ectopic tachycardia
<5%
AFL
Atrial flutter
<2%
AVRT due to an accessory pathway is the most common neonatal SVT.
Neonatal Supraventricular Tachycardia08
Section 04 · Types

Atrioventricular re-entrant tachycardia

AVRT60–70%
Mechanism

An accessory pathway connects atrium and ventricle outside the AV node.

Atrium → AV node → Ventricle → Accessory pathway → Atrium.

Associations
  • Wolff-Parkinson-White syndrome
  • Concealed accessory pathways
The most common neonatal SVT.
1 2 3 4 Accessorypathway
Neonatal Supraventricular Tachycardia09
Section 04 · Types

Atrial tachycardia

AT15–25%
Mechanism

An automatic ectopic focus within the atrium fires independently.

Features
  • Often incessant
  • Can cause cardiomyopathy
  • Less responsive to adenosine
Automaticectopic focus
Neonatal Supraventricular Tachycardia10
Section 04 · Types

AV nodal re-entrant tachycardia

AVNRT10–15%
Mechanism

Re-entry using a fast and a slow AV nodal pathway — the whole circuit sits within the AV node.

Uncommon in neonates.
FAST SLOW AV node
Neonatal Supraventricular Tachycardia11
Section 04 · Types

Junctional ectopic tachycardia

JET<5%
Mechanism

Arises near the AV junction.

Features
  • Often postoperative
  • Can be difficult to control
Focus at theAV junction
Neonatal Supraventricular Tachycardia12
Section 04 · Types

Atrial flutter

AFL<2%
Mechanism

Macro re-entry within the atrium.

Features
  • Atrial rate 300–500 bpm
  • Saw-tooth flutter waves
  • Often associated with congenital heart disease
300–500 bpm Macro re-entrywithin the atrium
Neonatal Supraventricular Tachycardia13
Section 04 · Types

Atrial flutter on the ECG

Atrial flutteratrial rate 300 bpm · 2:1 conduction · schematic
Saw-tooth flutter waves with 2:1 atrioventricular conduction — schematic
Neonatal Supraventricular Tachycardia14
05
Section 05

Causes & Associations

Idiopathic in most — but look for the exceptions
Section 05 · Causes

Most cases have no structural cause

Idiopathic
70%
No structural abnormality identified
IDIOPATHIC · 70%OTHER · 30%
The remaining causes
BCongenital heart disease
CPerinatal conditions
DElectrolyte disturbances
ERare genetic causes
Neonatal Supraventricular Tachycardia15
Section 05 · Causes · B

Congenital heart disease

Atrialised RVDisplaced tricuspid valveEnlarged right atrium
Ebstein anomaly — schematic
Ebstein anomaly
Hypertrophic cardiomyopathy
Tricuspid atresia
Congenitally corrected transposition
Important association
Ebstein anomaly has the strongest association with WPW.
Neonatal Supraventricular Tachycardia16
Section 05 · Causes · C – E

Perinatal, metabolic and genetic

C

Perinatal conditions

  • Birth asphyxia
  • Hypoxia
  • Sepsis
  • Respiratory distress
D

Electrolyte disturbances

  • Hypokalemia
  • Hyperkalemia
  • Hypocalcemia
  • Hypomagnesemia
E

Rare genetic causes

  • Long QT syndrome
  • Other channelopathies
Neonatal Supraventricular Tachycardia17
06
Section 06

ECG Recognition

Reading the rhythm at the bedside
Section 06 · ECG recognition

The typical SVT tracing

Supraventricular tachycardia280 bpm · schematic · 25 mm/s, 10 mV/mm
01

Heart rate 220–300 bpm

02

Regular rhythm

03

Narrow QRS complexes

04

No visible P waves

05

Fixed RR interval

06

Sudden onset

07

Sudden termination

Neonatal Supraventricular Tachycardia18
Section 06 · ECG recognition

Normal sinus rhythm

Normal sinus rhythm — neonate140 bpm · schematic · 25 mm/s, 10 mV/mm
Neonatal sinus rhythm at 140 bpm — schematic
Characteristics
01

Visible P wave before every QRS

02

Rate usually 120–160 bpm

03

Slight RR variability

Neonatal Supraventricular Tachycardia19
Section 06 · ECG recognition

A real 12-lead in sinus rhythm

Reference 12-lead — labelled age 5 years
The rate range quoted is for the neonate; the reference tracing shown is labelled age 5 years.
Neonatal Supraventricular Tachycardia20
Section 06 · ECG recognition

Neonatal SVT

Supraventricular tachycardia280 bpm · schematic · 25 mm/s, 10 mV/mm
Supraventricular tachycardia at 280 bpm — schematic
Characteristics
01

Rate 250–300 bpm

02

Very regular rhythm

03

P waves absent or buried

04

Narrow QRS complexes

Neonatal Supraventricular Tachycardia21
Section 06 · ECG recognition

SVT — 12-lead example

12-lead ECG in supraventricular tachycardia
Neonatal Supraventricular Tachycardia22
Section 06 · ECG recognition

SVT — a further example

12-lead ECG in supraventricular tachycardia
Neonatal Supraventricular Tachycardia23
Section 06 · ECG recognition

Where the P wave sits in AVNRT

P-wave position relative to the QRS in AVNRT
Neonatal Supraventricular Tachycardia24
Section 06 · ECG recognition

WPW pattern after conversion

Pre-excitation after conversionschematicNormalPre-excitedshort PRwide QRSnormal PRnormal QRSdelta wave
Normal versus pre-excited complex — schematic
Look for
01

Short PR interval

02

Delta wave

03

Wide QRS

Neonatal Supraventricular Tachycardia25
Section 06 · ECG recognition

Delta wave — clinical example

Delta wave, short PR interval and broad QRS
Neonatal Supraventricular Tachycardia26
Section 06 · ECG recognition

The post-conversion 12-lead

12-lead ECG recorded after conversion to sinus rhythm
Always obtain a post-conversion ECG — this is where pre-excitation is found.
Neonatal Supraventricular Tachycardia27
07
Section 07

Sinus Tachycardia vs SVT

The discrimination that changes management
Section 07 · Discrimination

Sinus tachycardia vs SVT

Sinus tachycardiavisible P wave · variable RRSVTno visible P wave · fixed RR
Sinus tachycardia
SVT
Usually 160–200 bpm
Rate
>220 bpm
Gradual
Onset
Sudden
Gradual
Offset
Sudden
Visible
P waves
Absent / retrograde
Variable
RR interval
Fixed
Slows rate
Vagal maneuver
May terminate rhythm
Neonatal Supraventricular Tachycardia28
08
Section 08

Clinical Presentation

A spectrum from irritability to shock
Section 08 · Clinical presentation

A spectrum of severity

Mild

01
  • Irritability
  • Poor feeding
  • Sweating
  • Pallor

Moderate

02
  • Tachypnea
  • Respiratory distress
  • Hepatomegaly

Severe

03
  • Heart failure
  • Hypotension
  • Cardiogenic shock
  • Altered consciousness
Escalating severity →
Neonatal Supraventricular Tachycardia29
09
Section 09

Management

Stability first, then the treatment ladder
Section 09 · Management

The treatment pathway at a glance

Neonate with SVT
Assess haemodynamic stability
Unstable
Immediate synchronized cardioversion
0.5–1 J/kg → 2 J/kg
Do not delay for medications
Stable
1
Vagal maneuvers
Ice-to-face
2
Adenosine
0.1 → 0.2 mg/kg
3
Amiodarone or procainamide
if adenosine fails
Neonatal Supraventricular Tachycardia30
Section 09 · Management · Step 1

Assess stability first

Signs of instability
01

Shock

02

Poor perfusion

03

Hypotension

04

Heart failure

05

Altered mental status

Any sign present
Immediate cardioversion
No signs present
Stepwise medical treatment
Neonatal Supraventricular Tachycardia31
Section 09 · Management · Unstable

Synchronized cardioversion

Unstable neonate
Immediate synchronized cardioversion
Do not delay cardioversion for medications.
+−Right upperchestApexSYNCHRONISED — shock delivered on the R waveFIRST SHOCK0.5–1 J/kgIF UNSUCCESSFUL2 J/kg
Pad position and synchronised delivery — schematic
Neonatal Supraventricular Tachycardia32
Section 09 · Management · Stable · First line

Vagal maneuvers

Preferred method
Ice-to-face (diving reflex)
Technique
  • Ice bag or ice-cold saline bag
  • Cover nose and eyes
  • Duration 5–10 seconds
Success rate
50–70%
Never use
✕  Ocular pressure
✕  Carotid massage
ICE · 5–10 SECONDSCovernose and eyesIce bag orice-cold salineSUCCESS RATE50–70%
Ice-to-face technique — schematic
Neonatal Supraventricular Tachycardia33
Section 09 · Management · Stable · Second line

Adenosine

Initial dose
0.1 mg/kg
rapid IV push
Maximum 3 mg
Repeat dose
0.2 mg/kg
rapid IV push
Maximum 6 mg
Immediately followed by
5–10 mL saline flush
Neonatal Supraventricular Tachycardia34
Section 09 · Management · Adenosine

The expected response

Expected response to adenosineschematic — not a patient tracingADENOSINESVTPause · 3–6 s asystole is normalSinus rhythm
SVT → pause → sinus rhythm
Sequence
SVT → Pause → Sinus rhythm
Important
A short period of asystole (3–6 seconds) is normal.
Neonatal Supraventricular Tachycardia35
Section 09 · Management · Third line

If adenosine fails

Amiodarone

Loading dose
5 mg/kg
IV over 30–60 minutes

Procainamide

Loading dose
15 mg/kg
IV over 30–60 minutes
Neonatal Supraventricular Tachycardia36
10
Section 10

Medications to Avoid

Two agents that can cause harm
Section 10 · Safety

Medications to avoid

Contraindicated

Verapamil

in infants under 1 year of age
May cause
Severe hypotension
Cardiovascular collapse
Asystole
Caution

Digoxin

Use cautiously in WPW syndrome.
Neonatal Supraventricular Tachycardia37
11
Section 11

Post-Conversion Evaluation

What must be done once sinus rhythm returns
Section 11 · After conversion

What must be done next

1

12-lead ECG

  • Delta wave
  • Short PR interval
  • WPW syndrome
2

Echocardiography

  • Structural abnormalities
  • Ventricular function
3

Laboratory tests

  • Potassium
  • Calcium
  • Magnesium
  • Glucose
Neonatal Supraventricular Tachycardia38
12
Section 12

Long-Term Management

Prophylaxis and definitive therapy
Section 12 · Long-term management

Prophylaxis and definitive therapy

Prophylaxis

Most commonly
Propranolol
Alternative agents
Flecainide
Sotalol
Digoxin (selected cases)

Catheter ablation

Reserved for
  • Drug-resistant SVT
  • Life-threatening episodes
  • Older infants and children
Neonatal Supraventricular Tachycardia39
13
Section 13

Prognosis

Excellent — with prompt treatment
Section 13 · Prognosis

Overall outcome is excellent

Spontaneous resolution
50–80%
of infants, usually by 6–12 months of age
Mortality
<1%
with prompt diagnosis and treatment
Recurrence risk
30–40%
Most recurrences occur within the first 2–3 months, and within the first year of life.
Overall outcome
Excellent.Most neonatal SVT resolves spontaneously during infancy.
Neonatal Supraventricular Tachycardia40
Section 13 · Prognosis

Poor prognostic factors

01

Structural heart disease

02

Fetal hydrops

03

Incessant tachycardia

04

Tachycardia-induced cardiomyopathy

05

Delayed diagnosis

Early recognition and treatment prevent heart failure and tachycardia-induced cardiomyopathy.
Neonatal Supraventricular Tachycardia41
14
Section 14

Key Messages

Ten points to carry out of this room
Section 14 · Key messages

Ten points to take away

01

Any neonate with a heart rate >220 bpm should be evaluated for SVT.

02

AVRT due to an accessory pathway is the most common neonatal SVT.

03

ECG usually shows a regular narrow-complex tachycardia with absent P waves.

04

The preferred vagal maneuver in neonates is the ice-to-face (diving reflex) technique.

05

Adenosine is the first-line medication for stable SVT.

Neonatal Supraventricular Tachycardia42
Section 14 · Key messages

Ten points to take away (continued)

06

Verapamil is contraindicated in infants younger than 1 year.

07

Unstable patients require immediate synchronized cardioversion.

08

Always obtain a post-conversion ECG to identify WPW syndrome.

09

Most neonatal SVT resolves spontaneously during infancy.

10

Early recognition and treatment prevent heart failure and tachycardia-induced cardiomyopathy.

Neonatal Supraventricular Tachycardia43

Thank you

Questions and discussion
Presented by
Dr. Amr Alashmawy

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