Step	Adult Bradycardia Algorithm
1	🚨 Assess for adverse features: Shock, syncope, MI/ischaemia, acute HF → treat as unstable
2	📞 Call help + monitor + pads on. Get ECG/SpO₂/BP; apply pacing pads early
3	🩺 ABCDE + IV access + 12-lead ECG. Consider Bloods: U&E/Mg/glucose ± ABG/VBG if unwell
4	💉 Atropine 500 micrograms IV every 3-5 mins as needed (repeat) . Max 3 mg
5	⚡ If no response / high-grade block → pacing. Transcutaneous now → prepare transvenous. Call cardiology. Move to CCU or pacing room if needed
6	💧 Bridge infusion if needed. Adrenaline 2–10 mcg/min OR isoprenaline (local protocol)
7	🧩 Treat reversible causes: Stop AV-nodal drugs; treat MI, hyperkalaemia, hypoxia

📖 About

Common causes: Acute MI, ageing conduction tissue, endocarditis, rate-slowing drugs.
Physiological bradycardia: athletes, during sleep (Mobitz I/Wenckebach).
Pacemaker failure: suspect if dizzy/faints; check ECG + pacing clinic review.

🩺 Causes at Different Levels

Sinus node: sick sinus, hypothyroidism.
AV node: complete heart block, slow AF.
His–Purkinje: bifascicular block (LAD + RBBB).
Acute MI:
- RCA infarct → AVN block (may resolve with reperfusion).
- LAD infarct → CHB or LBBB (often persistent).

🔍 Investigations

FBC, U&E (esp. K⁺, Mg²⁺), TFTs, troponin.
CXR (cardiomegaly, pulmonary oedema).
24-h ECG if intermittent symptoms.
Echocardiography if structural heart disease suspected.

⚠️ High Risk of Asystole

Recent asystole.
Mobitz II AV block.
Complete heart block with broad QRS.
Ventricular pause > 3 seconds.

💊 Management

Move to CCU/monitored bed if significant.
Atropine 500 mcg IV stat, repeat up to 3 mg.
Transcutaneous pacing if atropine ineffective.
Isoprenaline 5 mcg/min IV, or Adrenaline 2–10 mcg/min IV, or Dopamine 2–10 mcg/kg/min.
Glucagon IV (50–150 mcg/kg in 5% glucose) for β-blocker toxicity (protect airway).
If refractory ➝ transvenous pacing.

🧩 Temporary Pacing Indications

Acute MI + CHB (esp. anterior infarct).
Bundle branch block + trifascicular disease ➝ prophylactic pacing.
Sinoatrial disease with serious symptoms not responsive to atropine.
Pre-op if Type II or CHB + surgery planned.
Drug poisoning (β-blockers, digoxin, verapamil).
Symptomatic bradycardia unresponsive to meds.
Overdrive pacing: refractory VT/SVT (ICU only).
Asystolic arrest with P-wave activity (“ventricular standstill”).
Peri-cardiac surgery conduction block.

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Resuscitation - Adult Bradycardia Algorithm