A Practical Step-by-Step Guide
Based on RECAPEM Article by Dr. Shahriar Lahouti
🧠 INTRO: The “Slow HR” That Can Crash Fast
Bradycardia is common. But some kill.
The challenge? Separating the benign from the dangerous, while time-treating the unstable ones.
This isn’t just about rate — it’s about perfusion, pathology, and pace of deterioration.
🚦 Step 1: Diagnosis — It’s More Than the ECG
1. Is the patient unstable?
Look for:
- 🧠 AMS
- ❤️ Chest pain
- 💨 Dyspnea
- 📉 Hypotension or poor pulses
- 😰 Shock or impending arrest
👉 If YES → skip to treatment while working up cause.
2. Start with the ECG — but don’t get stuck in block types
Focus on these diagnostic clues:
| Clue | Implication |
|---|---|
| Narrow QRS + regular rhythm | Likely nodal — may respond to atropine |
| Wide QRS + brady | Infranodal block — may not respond to atropine, pacing often needed |
| High-degree AV block | Often unstable, consider pacing early |
| Sinus brady + hypotension | Search for underlying cause (e.g., MI, drugs, vagal) |
3. Bedside Ultrasound = Rapid Differentiator
Use POCUS to rule in/out:
- 💧 Pericardial tamponade (RV collapse, IVC plethora)
- ❤️ RWMA (posterior/inferior MI with brady)
- 🩺 Volume status, IVC collapsibility
- 🫁 Tension pneumothorax (lung slide, absence)
4. Ask: What’s Causing This?
Mnemonic: DIE HARD
- Drugs: BBs, CCBs, digoxin, opioids
- Ischemia: esp. inferior MI (RCA → SA/AV node)
- Electrolytes: hyperkalemia
- Hypoxia, H+ (acidosis)
- Autonomic (vasovagal, high vagal tone in athletes)
- Reflexes: carotid massage, suctioning
- Degenerative/conduction system disease
⚠️ Pitfalls to Avoid
❌ Assuming sinus brady is always benign
— In elderly, it can precede asystole.
— In trauma, may signal increased ICP or impending herniation.
❌ Waiting for atropine to fail before prepping pacing
— In high-grade AV blocks, atropine often doesn’t work.
— Pads on early saves lives.
❌ Treating only the heart rate
— Bradycardia may be compensatory: e.g., beta-blocker toxicity, hypothermia, hypothyroid → slow and hypotensive.
❌ Missing brady from MI
— Especially inferior MI or RV infarcts: look for ST elevation in II, III, aVF ± V1 (RV leads)
💊 Step 2: Treat the Unstable — Pharmacologic Management
🟥 ATROPINE — 1st line
- Dose: 0.5 mg IV q3–5 min (max 3 mg)
- Works for vagal or nodal causes
- Unreliable in Mobitz II, 3rd degree block, transplant
🟪 Epinephrine — 2–10 mcg/min infusion
- For hypotensive bradycardia
- α + β agonist = HR + BP support
🟩 Dopamine — 2–20 mcg/kg/min
- Similar to epi; use in patients needing pressor + HR support
🟦 Isoproterenol — 2–10 mcg/min
- Transplant patients, β-blocker overdose
- Pure β agonist → caution in hypotension
🟨 Glucagon — 3–10 mg IV bolus + infusion
- For BB/CCB OD
🟧 Calcium Gluconate/Chloride — 1–2 g
- For hyperK or CCB toxicity
🟫 High-dose insulin (HDI) + Dextrose
- For BB/CCB OD; improves inotropy via metabolic pathway
🔵 Magnesium — 1–2 g IV
- For torsades / long QT
⚡ Step 3: If Drugs Fail — Start Pacing
Transcutaneous Pacing (TCP)
- Place early — often underused
- Start at 60–80 bpm, increase mA until capture
Transvenous Pacing (TVP)
- Indicated for high-degree AV block or refractory unstable brady
🧠 Pro Tip: If ECG shows wide QRS with long pauses or HR <30 → prepare to pace before full arrest hits.
🔧 Pacemaker Malfunction? Know the Patterns
| Problem | Clue |
|---|---|
| No pacer spikes | Failure to pace |
| Spikes but no QRS | Failure to capture |
| Random spikes | Failure to sense |
| Post-MRI or magnet use | Reset mode may cause unexpected brady |
🧲 Use a magnet to force asynchronous pacing (VOO/DOO) if needed urgently.
✅ Final Checklist for the Crashing Bradycardia
🔲 Assess for perfusion, not just rate
🔲 Start atropine if appropriate
🔲 Prep epinephrine/dopamine drip early
🔲 Identify reversible causes
🔲 Use POCUS for diagnosis
🔲 Initiate pacing early if needed
🔲 Call cardiology/ICU early if transvenous pacing or further workup needed
🔲 Monitor for sudden deterioration (wide QRS, pauses, blocks)
📌 Reference: Full article at recapem.com
#EmergencyMedicine #Bradycardia #ResusMindset #CriticalCare #EDPharmacology #Pacing #ECG #Toxicology #RECAPEM #EMMasteryAcademy #OwnTheResusRoom
