ACLS – TACHYCARDIA ALGORITHM
Tachycardia is defined as a heart rate >100 bpm. In ACLS, management depends on whether the tachycardia is stable or unstable, and whether the QRS complex is narrow (<0.12 sec) or wide (>0.12 sec).
The ACLS Tachycardia Algorithm provides a structured approach to identify and treat tachyarrhythmias appropriately. Early recognition and timely intervention are critical to prevent deterioration into cardiac arrest.
WHY IT’S IMPORTANT
Ensures a systematic approach to managing tachyarrhythmias. Helps differentiate between stable vs. unstable tachycardia. Guides appropriate treatment (cardioversion, medications, or observation). Prevents progression to life-threatening conditions, including ventricular fibrillation (VF) or pulseless VT.
INITIAL ASSESSMENT – IS THE PATIENT STABLE OR UNSTABLE?
Tachycardia is clinically significant when it causes:
Hypotension (SBP <90 mmHg). Altered mental status (confusion, dizziness, syncope). Signs of shock (cool extremities, weak pulses, delayed cap refill). Chest pain (ischemia or poor coronary perfusion). Acute heart failure (pulmonary congestion, dyspnea).
KEY DECISION POINT:
Unstable Tachycardia? → Immediate Synchronized Cardioversion!
Stable Tachycardia? → Proceed with QRS assessment (narrow vs. wide).
Signs of UNSTABLE Tachycardia Immediate Action
Hypotension (SBP <90 mmHg) Synchronized Cardioversion
Acute altered mental status Synchronized Cardioversion
Signs of shock Synchronized Cardioversion
Chest pain (ischemia) Synchronized Cardioversion
Acute heart failure Synchronized Cardioversion
If the patient is STABLE, determine whether the QRS is narrow or wide.
MANAGEMENT OF UNSTABLE TACHYCARDIA
Immediate Synchronized Cardioversion!
Perform synchronized cardioversion according to the type of tachycardia:
Rhythm Type Initial Shock Energy
Narrow regular (SVT, atrial flutter) 50-100 J
Narrow irregular (AFib) 120-200 J
Wide regular (VT with pulse) 100 J
Wide irregular (Polymorphic VT, Torsades de Pointes) Defibrillation (NOT synchronized!)
Consider Sedation if time permits before cardioversion.
MANAGEMENT OF STABLE TACHYCARDIA (QRS ASSESSMENT)
Once you confirm the patient is stable, determine if the QRS complex is narrow (<0.12 sec) or wide (>0.12 sec).
NARROW QRS TACHYCARDIA (QRS <0.12 sec)
Likely Supraventricular Tachycardia (SVT) or Atrial Flutter.
Try Vagal Maneuvers (e.g., Valsalva maneuver, carotid massage if no contraindications). Administer Adenosine:
- 6 mg IV push (followed by 20 mL saline flush).
- If ineffective → Repeat with 12 mg IV push. If SVT persists, consider:
- Beta-blockers (e.g., Metoprolol 5 mg IV over 5 min) OR
- Calcium channel blockers (e.g., Diltiazem 0.25 mg/kg IV over 2 min).
DO NOT give adenosine for atrial fibrillation or flutter!
WIDE QRS TACHYCARDIA (QRS ≥0.12 sec)
Likely Ventricular Tachycardia (VT) or SVT with aberrancy.
Consider Adenosine 6 mg IV (ONLY if regular & monomorphic). Administer Antiarrhythmic Therapy:
- Amiodarone: 150 mg IV over 10 min, repeat as needed.
- OR Procainamide: 20-50 mg/min IV until arrhythmia resolves.
- OR Sotalol: 100 mg IV over 5 min (Avoid if prolonged QT). Consult an expert if uncertain or if rhythm persists.
DO NOT give calcium channel blockers or beta-blockers for irregular wide-complex tachycardia!
IDENTIFYING & TREATING UNDERLYING CAUSES
Tachycardia is often a symptom of an underlying problem. Identifying and treating reversible causes is critical.
Common Causes of Tachycardia (Mnemonic: “The 5 Hs & 5 Ts”)
| H Causes (Metabolic & Circulatory Issues) | T Causes (Structural or Toxic Issues) |
|---|---|
| Hypovolemia → Fluid loss leading to compensatory tachycardia. | Toxins (e.g., stimulants, beta-agonists) → Drug-induced tachycardia. |
| Hypoxia → Low oxygen triggers increased heart rate. | Tamponade (Cardiac) → Fluid in the pericardium restricting heart function. |
| Hydrogen ion (Acidosis) → Acid-base imbalance affecting heart function. | Tension Pneumothorax → Compressed lung affects circulation. |
| Hyperkalemia/Hypokalemia → Potassium imbalances affect conduction. | Thrombosis (Coronary or Pulmonary) → Heart attack (MI) or Pulmonary Embolism (PE). |
| Hypothermia → Low temperatures affect conduction & contractility. | Trauma (Head Injury, Increased ICP) → Neurologic causes of tachyarrhythmias. |
Key Takeaway: If tachycardia is caused by an underlying condition, treating that condition is essential for stabilization.
SUMMARY – ACLS TACHYCARDIA ALGORITHM
If the patient is UNSTABLE: Immediate synchronized cardioversion based on rhythm type. Consider sedation if time permits.
If the patient is STABLE: Assess QRS width to determine treatment approach. Narrow QRS (<0.12 sec, likely SVT or AFlutter):
- Vagal maneuvers → Adenosine → Beta-blockers or Calcium channel blockers. Wide QRS (>0.12 sec, likely VT or SVT with aberrancy):
- Adenosine (ONLY if monomorphic & regular).
- Amiodarone / Procainamide / Sotalol as antiarrhythmics.
COMMON TACHYCARDIA MISTAKES & HOW TO AVOID THEM
| Mistake | Impact | Prevention |
|---|---|---|
| Not performing cardioversion in unstable patients | Progression to cardiac arrest | Shock immediately if unstable |
| Giving adenosine for AFib/flutter | Ineffective & may cause hypotension | Use rate control (BB or CCBs) instead |
| Misinterpreting polymorphic VT (Torsades) as monomorphic VT | Incorrect treatment (amiodarone worsens torsades) | Use magnesium sulfate for Torsades |
| Not addressing the underlying cause | Tachycardia persists | Treat Hs & Ts |