BRADYCARDIA ALGORITHM (ACLS)
The Bradycardia Algorithm provides a structured approach to managing patients with symptomatic bradycardia (slow heart rate). Bradycardia is clinically significant when it causes symptoms such as hypotension, altered mental status, chest pain, shortness of breath, or signs of shock.
Why It’s Important:
Ensures a systematic response to life-threatening bradycardia. Guides treatment with medications, pacing, and infusion therapy. Helps identify and correct reversible causes of bradycardia.
INITIAL ASSESSMENT: RECOGNIZING BRADYCARDIA
Bradycardia is defined as a heart rate <60 bpm. However, not all cases require treatment. The key decision point: Is the patient symptomatic and unstable?
Step 1: Assess for Symptoms of Unstable Bradycardia
| Sign/Symptom | Clinical Significance |
|---|---|
| Hypotension (SBP <90 mmHg) | Low cardiac output |
| Altered Mental Status | Reduced brain perfusion |
| Chest Pain | Myocardial ischemia |
| Signs of Shock | Organ hypoperfusion |
| Shortness of Breath | Pulmonary congestion |
If symptomatic, immediate intervention is required!
Step 2: Identify & Monitor the Rhythm
- Attach a cardiac monitor (ECG) and pulse oximeter.
- Obtain blood pressure and IV access.
- Determine if the bradycardia is causing instability.
IS THE BRADYCARDIA CAUSING SYMPTOMS?
If NO symptoms → Monitor & Observe. If YES → Immediate treatment is required.
Key Takeaway: Symptomatic bradycardia requires urgent intervention!
TREATMENT OF SYMPTOMATIC BRADYCARDIA
First-line drug: ATROPINE If Atropine is ineffective → Pacing, Dopamine, or Epinephrine
Step 1: Administer Atropine (First-Line Treatment)
Atropine Dose: 0.5 mg IV every 3-5 minutes (MAX: 3 mg). Atropine increases heart rate by blocking the vagus nerve.
Atropine is NOT effective in:
- Second-degree Type II AV block
- Third-degree (Complete) AV block
- Patients post-cardiac transplant
If Atropine is ineffective, IMMEDIATE pacing or infusion therapy is required!
Step 2: If Atropine Fails → Consider These Options:
Transcutaneous Pacing (TCP) – Immediate Action
- Apply pacing pads to the chest and start external pacing.
- Set pacing rate to ~60 bpm and increase energy until capture is achieved.
Dopamine Infusion – If Pacing Not Available
- Dose: 2-20 mcg/kg/min IV drip
- Titrate to maintain adequate blood pressure and perfusion.
Epinephrine Infusion – Alternative to Dopamine
- Dose: 2-10 mcg/min IV infusion
- Increases heart rate and contractility.
Key Takeaway: If Atropine does not work, pacing or infusion therapy is required immediately!
WHEN TO CONSIDER TRANSVENOUS PACING?
Transvenous pacing is indicated for persistent unstable bradycardia despite transcutaneous pacing and medications. A pacing wire is inserted into a central vein and guided into the right ventricle.
Use transvenous pacing in high-degree AV blocks!
ASYMPTOMATIC BRADYCARDIA: MONITOR & OBSERVE
If the patient is bradycardic but has NO symptoms, NO immediate intervention is needed. Continue monitoring for deterioration and identify underlying causes.
IDENTIFYING & TREATING UNDERLYING CAUSES
Bradycardia can be caused by reversible conditions that must be corrected.
Common Causes of Bradycardia (Mnemonic: “The 5 Hs & 5 Ts”)
H Causes (Metabolic & Circulatory Issues)
| H Cause | Description |
|---|---|
| Hypoxia | Low oxygen levels slow heart rate |
| Hypothermia | Core body temperature <30°C (86°F) |
| Hypovolemia | Low blood volume (shock) |
| Hydrogen ion (Acidosis) | Metabolic or respiratory acidosis |
| Hyperkalemia/Hypokalemia | Potassium imbalances affect heart conduction |
T Causes (Structural or Toxic Issues)
| T Cause | Description |
|---|---|
| Toxins (e.g., beta-blockers, calcium channel blockers, digoxin overdose) | Drug-induced bradycardia |
| Tamponade (Cardiac) | Fluid buildup restricts heart movement |
| Tension Pneumothorax | Increased pressure on the heart |
| Thrombosis (Coronary or Pulmonary) | Heart attack (MI) or Pulmonary Embolism (PE) |
| Trauma (Head Injury, Increased ICP) | Increased intracranial pressure slows the heart |
Key Takeaway: If bradycardia is caused by an underlying condition, treating that condition is critical!
BRADYCARDIA TREATMENT SUMMARY
If the patient is UNSTABLE (symptomatic bradycardia):
Give Atropine 0.5 mg IV every 3-5 min (Max 3 mg). If Atropine fails:
- Begin Transcutaneous Pacing (TCP).
- Start Dopamine (2-20 mcg/kg/min) OR Epinephrine (2-10 mcg/min) infusion. If the patient remains unstable, prepare for transvenous pacing. Search for and treat underlying causes (Hs & Ts).
If the patient is STABLE (asymptomatic bradycardia):
Monitor & observe. Identify & treat underlying causes (Hs & Ts).
Key Takeaway: Unstable bradycardia requires immediate intervention with Atropine, pacing, or infusion therapy.
COMMON BRADYCARDIA MISTAKES & HOW TO AVOID THEM
Mistake Impact Prevention
Delaying Treatment in Unstable Patients Worsening perfusion, possible cardiac arrest Immediately give Atropine, start pacing if needed
Not Recognizing High-Degree AV Blocks Atropine is ineffective Go directly to pacing for Type II or 3rd-degree blocks
Failure to Identify Reversible Causes Persistent bradycardia despite treatment Always assess Hs & Ts
Using Dopamine/Epinephrine as First-Line Therapy Slower onset of action compared to Atropine Atropine is first-line, unless high-degree block present
Key Takeaway: Early intervention and correct pacing strategies improve patient outcomes!
SUMMARY: MASTERING THE BRADYCARDIA ALGORITHM
Bradycardia is treated ONLY if symptomatic (unstable). Atropine (0.5 mg IV every 3-5 min, max 3 mg) is first-line. If Atropine fails, initiate pacing OR start a Dopamine/Epinephrine infusion. Transcutaneous pacing is needed for high-degree AV blocks. Identify and treat reversible causes (Hs & Ts).
Takeaway: Bradycardia management requires rapid recognition, appropriate interventions, and treating underlying causes. Early pacing can be life-saving!