Neonatal Arrhythmia Management

Initial Assessment

flowchart TD
    A[Neonate with<br/>Arrhythmia] --> B{Hemodynamically<br/>Stable?}

    B -->|No - Shock/HF| C[EMERGENCY<br/>Immediate Intervention]
    B -->|Yes| D{Rate?}

    C --> C1{Tachycardia<br/>or Bradycardia?}
    C1 -->|Tachy| C2[Synchronized<br/>Cardioversion 0.5-1 J/kg]
    C1 -->|Brady| C3[Atropine 0.02 mg/kg<br/>Epinephrine 0.01 mg/kg<br/>Pacing]

    D -->|Fast >180| E[Tachycardia<br/>Workup]
    D -->|Slow <100| F[Bradycardia<br/>Workup]
    D -->|Normal 100-180| G[Ectopy<br/>Evaluation]

    E --> E1{Narrow or<br/>Wide QRS?}
    E1 -->|Narrow| E2[SVT vs<br/>Sinus Tach]
    E1 -->|Wide| E3[VT vs SVT<br/>with aberrancy]

    F --> F1{AV Block?}
    F1 -->|Yes| F2[Degree of<br/>Block]
    F1 -->|No| F3[Sinus Brady<br/>or Sinus Node Dysfx]

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**Neonatal Arrhythmia Initial Assessment** 1. **Hemodynamically Stable?** - **NO (Shock/HF)** → EMERGENCY: Tachy → Cardioversion 0.5-1 J/kg; Brady → Atropine/Epi/Pacing - **YES** → Check rate 2. **Rate Assessment:** - Fast >180 → Tachycardia workup → Narrow (SVT vs Sinus) or Wide (VT vs aberrant) - Slow <100 → Bradycardia workup → AV block? Degree or Sinus dysfunction - Normal 100-180 → Ectopy evaluation

Neonatal SVT

Recognition

ECG Features: - Rate typically 220-300 bpm (can be lower in sick neonates) - Narrow QRS (unless aberrancy or WPW) - Regular rhythm - No beat-to-beat variability - P waves may be hidden or retrograde

Differentiation from Sinus Tachycardia:

Feature	SVT	Sinus Tachycardia
Rate	Usually >220	Usually <220
Onset	Abrupt	Gradual
Rate variability	None (fixed rate)	Beat-to-beat variation
P waves	Absent/retrograde	Normal P before each QRS
Cause	Accessory pathway	Fever, pain, hypovolemia

Acute Management Algorithm

flowchart TD
    A[Confirmed SVT<br/>in Neonate] --> B{Hemodynamically<br/>Stable?}

    B -->|No| C[Synchronized Cardioversion<br/>0.5-1 J/kg → 2 J/kg]
    B -->|Yes| D[Vagal Maneuvers]

    D --> D1[Ice to face<br/>15-20 seconds]
    D1 --> E{Converted?}

    E -->|Yes| F[12-lead ECG<br/>Look for WPW]
    E -->|No| G[Adenosine]

    G --> G1[First dose: 0.1 mg/kg<br/>Rapid IV push + flush]
    G1 --> H{Converted?}

    H -->|Yes| F
    H -->|No| I[Adenosine 0.2 mg/kg<br/>Max 0.3 mg/kg]

    I --> J{Converted?}
    J -->|Yes| F
    J -->|No| K[Consider:<br/>Amiodarone or Procainamide<br/>or Cardioversion]

    F --> L[Start Maintenance<br/>Prophylaxis]

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**Neonatal SVT Acute Management** 1. **Hemodynamically Stable?** - **NO** → Synchronized Cardioversion 0.5-1 J/kg → 2 J/kg - **YES** → Vagal maneuvers (ice to face 15-20 sec) 2. **If Vagal Fails:** Adenosine 0.1 mg/kg rapid IV push - Converted? → 12-lead ECG (look for WPW) → Start maintenance - Not converted → Adenosine 0.2 mg/kg (max 0.3) → Still not → Amiodarone/Procainamide/Cardioversion

Adenosine Dosing

Attempt	Dose	Notes
First	0.1 mg/kg	Rapid push, closest port to heart
Second	0.2 mg/kg	If first fails
Third	0.3 mg/kg	Maximum dose

Key Points: - Must be given FAST (half-life 10 seconds) - Use two-syringe technique (adenosine + flush) - Ensure good IV access (central or proximal peripheral) - Record rhythm strip during administration

Maintenance Therapy

flowchart TD
    A[SVT Converted<br/>Start Prophylaxis] --> B{WPW on baseline<br/>ECG?}

    B -->|Yes - WPW| C[Avoid AV nodal blockers alone]
    B -->|No WPW| D[First-line Options]

    C --> C1[Flecainide preferred<br/>or Propranolol + Flecainide]

    D --> D1[Propranolol<br/>1-4 mg/kg/day divided TID-QID]
    D --> D2[Nadolol<br/>1-2 mg/kg/day once daily]
    D --> D3[Digoxin<br/>8-10 mcg/kg/day divided BID]

    D1 & D2 & D3 --> E[Continue until age 1 year]
    E --> F[Trial off medication<br/>~80% don't recur]

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**Neonatal SVT Maintenance Therapy** 1. **Check baseline ECG for WPW:** - **WPW present** → Avoid AV nodal blockers alone → Flecainide preferred - **No WPW** → First-line: Propranolol (1-4 mg/kg/day TID-QID), Nadolol (1-2 mg/kg/day), or Digoxin (8-10 mcg/kg/day BID) 2. **Duration:** Continue until age 1 year → Trial off (~80% don't recur)

Drug Selection:

Drug	Dose	Pros	Cons
Propranolol	1-4 mg/kg/day TID-QID	First-line, effective	TID-QID dosing
Nadolol	1-2 mg/kg/day daily	Once daily	Less data in neonates
Digoxin	8-10 mcg/kg/day BID	Effective	Contraindicated in WPW
Flecainide	2-4 mg/kg/day BID	Good for WPW	Need level monitoring
Sotalol	2-4 mg/kg/day BID	Effective	QT prolongation

Neonatal Bradycardia

Congenital Complete Heart Block (CCHB)

When to Suspect: - Fetal bradycardia (often detected in utero) - Maternal lupus or Sjögren's syndrome (anti-Ro/La antibodies) - Structural CHD (L-TGA, AV canal defects) - Persistent neonatal HR <60-80 bpm

ECG Features: - AV dissociation (P waves and QRS independent) - Regular P-P interval - Regular R-R interval (usually) - P rate > QRS rate

Etiology:

Type	Cause	Associated
Immune-mediated	Anti-Ro/La antibodies	Maternal SLE, Sjögren's
Structural	CHD with AV node abnormality	L-TGA, AVSD
Idiopathic	Unknown	Normal heart

CCHB Management

flowchart TD
    A[Neonatal CCHB<br/>Diagnosed] --> B{Symptomatic/<br/>Hemodynamically<br/>Compromised?}

    B -->|Yes| C[Emergency Pacing]
    B -->|No| D[Close Monitoring]

    C --> C1[Isoproterenol drip<br/>0.01-0.1 mcg/kg/min]
    C --> C2[Temporary pacing wire<br/>or Transcutaneous pacing]
    C --> C3[Permanent Pacemaker]

    D --> D1{Criteria for<br/>Pacemaker?}

    D1 -->|Yes| C3
    D1 -->|No| E[Continue Monitoring<br/>Weekly/Biweekly]

    C3 --> F[Epicardial leads<br/>in neonates/infants]

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**CCHB Management** 1. **Symptomatic/Compromised?** - **YES** → Emergency pacing: Isoproterenol 0.01-0.1 mcg/kg/min + Temp pacing → Permanent pacemaker (epicardial) - **NO** → Close monitoring → Meet pacemaker criteria? → Permanent pacemaker or continue monitoring

Indications for Pacemaker (Class I):

• Ventricular rate <55 bpm (OR <70 if CHD)
• Symptoms (poor feeding, HF, fatigue)
• Wide QRS escape rhythm
• Ventricular dysfunction
• QTc prolongation
• Complex ventricular ectopy

Indications for Pacemaker (Class IIa):

• Asymptomatic but rate <50 bpm
• Resting HR <70 even if asymptomatic

Sinus Bradycardia in Neonates

Causes: - Vagal stimulation (suctioning, feeding) - Hypoxia - Hypothermia - Hypoglycemia - Increased ICP - Medications (maternal beta-blockers) - Sick sinus syndrome (rare in neonates)

Approach: 1. Identify and treat underlying cause 2. Ensure adequate oxygenation 3. Most cases self-resolve 4. Symptomatic treatment if needed (atropine)

Neonatal Ectopy

Premature Atrial Contractions (PACs)

Characteristics: - Very common in neonates - Early P wave with different morphology - Conducted (followed by QRS) or blocked - Often bigeminal pattern

Management: - Benign - no treatment needed - Resolve spontaneously by 1 month in most - Avoid caffeine exposure - Follow-up in 4-6 weeks - Echo if frequent/persistent (exclude structural disease)

When to Worry: - Triggering SVT - Associated structural heart disease - Very frequent with hemodynamic compromise

Premature Ventricular Contractions (PVCs)

Less Common than PACs in Neonates

Characteristics: - Wide QRS, different morphology - No preceding P wave - Full compensatory pause

Concerning Features: - Frequent (>10% burden) - Multiform (multiple morphologies) - Couplets, triplets, or runs of VT - Associated with structural heart disease

Workup: - 12-lead ECG - Echocardiogram (rule out structural disease, tumor) - Holter monitor (quantify burden)

Management: - Isolated, infrequent PVCs: Observe - Frequent PVCs without heart disease: Usually benign, observe - With structural disease or significant burden: Consider treatment (beta-blocker)

Drug Dosing Reference

Drug	Indication	Neonatal Dose
Adenosine	Acute SVT	0.1-0.3 mg/kg IV push
Propranolol	SVT prophylaxis	1-4 mg/kg/day divided TID-QID
Nadolol	SVT prophylaxis	1-2 mg/kg/day daily
Digoxin	SVT prophylaxis (not WPW)	8-10 mcg/kg/day divided BID
Flecainide	SVT (especially WPW)	2-4 mg/kg/day divided BID
Amiodarone	Refractory SVT/VT	Load 5 mg/kg IV; 5-15 mg/kg/day
Isoproterenol	Bradycardia	0.01-0.1 mcg/kg/min
Atropine	Bradycardia	0.02 mg/kg IV

Key Teaching Points

1. SVT in neonates typically presents at HR 220-300 bpm
2. Ice to face is the preferred vagal maneuver in neonates
3. Adenosine must be given rapidly - use two-syringe technique
4. Digoxin is contraindicated in WPW - can cause VF
5. Most neonatal SVT resolves by age 1 year (~80%)
6. CCHB + maternal lupus = anti-Ro/La mediated damage
7. CCHB with HR <55 or symptoms requires pacemaker
8. PACs are benign and resolve spontaneously in most neonates