1️⃣ Bradyarrhythmias (Slow Rhythms)

Definition: HR <60 bpm with poor perfusion = treat immediately.

🌡️ Causes

Hypoxia (MOST COMMON), heart block, vagal stimulation, hypothermia, drugs.

🫀 Sinus Bradycardia

• Recognition: P waves present, regular rhythm, slow rate.
• Peds Tip: Normal in athletes/sleeping; NOT normal with poor perfusion.

🟪 AV Blocks

1° AV Block:

• PR prolonged (>0.20s adult-equivalent), but every P → QRS.
• Usually benign; watch for progression.

2° Type I (Wenckebach):

• PR progressively lengthens → dropped QRS.
• “Longer, longer, longer, drop ▶️ Wenckebach.”
• Usually transient, often vagal.

2° Type II:

• Normal PR intervals with random dropped QRS.
• Bad. Can progress to complete block.

3° Complete Heart Block:

• Atria + ventricles beat independently.
• Regular P waves, regular QRS—but no relationship.
• Often bradycardic, poor perfusion.

2️⃣ Tachyarrhythmias (Fast Rhythms)

Definition: Above age-appropriate range (often >180 infants, >160 children).

⚡ Supraventricular Tachycardia (SVT)

• Rate: 180–300 bpm
• P waves: Absent or hidden
• QRS: Narrow
• Onset: Abrupt
• Key Tip: Infant may just appear irritable, poor feeding, or pale.

⚡ Atrial Flutter

• Sawtooth F-waves
• Rate often 250–350
• Rare in kids (post-op congenital heart disease)

⚡ Ventricular Tachycardia (VT)

With Pulse:

• Wide QRS, regular rhythm
• Rate usually 120–250
• May have poor perfusion

Pulseless VT:

• Treat like VF (defibrillate)

💥 Ventricular Fibrillation (VF)

• Chaotic, no identifiable waves
• No pulse → CPR + defibrillate immediately

😵 Asystole (Flatline)

• No electrical activity
• Confirm in 2 leads
• CPR + epinephrine only (NO shock)

🌪️ PEA (Pulseless Electrical Activity)

• Organized electrical rhythm without a pulse
• Causes = H’s & T’s (hypoxia, hypovolemia, hypothermia, H+ acidosis, hypo/hyperK, tension pneumo, tamponade, toxins, thrombosis)

3️⃣ How to Rapidly Recognize Rhythms (PALS Algorithm)

Step 1: Pulse Check

• Present? → Rhythm with pulse
• Absent? → Treat as cardiac arrest rhythm

Step 2: Narrow vs. Wide QRS

• Narrow (<0.08s): SVT, sinus tach, atrial flutter/fib
• Wide (>0.08–0.12s): VT, aberrancy

Step 3: Regular vs. Irregular

• Regular: SVT, VT, sinus tach
• Irregular: Atrial fibrillation/flutter with variable block, polymorphic VT

Step 4: P Waves Present?

• Yes → sinus or atrial rhythm
• No → SVT or VT