What are the treatment options for tachycardia?

Treatment of Tachycardia

The treatment of tachycardia depends primarily on the type of tachycardia and the hemodynamic stability of the patient, with electrical cardioversion being the first-line treatment for any hemodynamically unstable tachycardia regardless of the specific type. 1

Initial Assessment and Classification

Hemodynamic Stability

• Unstable signs (require immediate intervention):
  • Systolic BP ≤ 90 mm Hg
  • Chest pain
  • Heart failure
  • Heart rate ≥ 150 beats/min with symptoms

Classification by QRS Complex

1. Narrow-complex tachycardia (QRS < 120 ms)

   • Sinus tachycardia
   • Atrial tachycardia
   • Atrial flutter
   • Atrial fibrillation
   • AV nodal reentrant tachycardia (AVNRT)
   • AV reentrant tachycardia (AVRT)

2. Wide-complex tachycardia (QRS ≥ 120 ms)

   • Ventricular tachycardia (VT)
   • SVT with aberrancy
   • Pre-excited tachycardias

Treatment Algorithm

Hemodynamically Unstable Patients (Any Tachycardia)

• Immediate synchronized electrical cardioversion (100J, 200J, 360J as needed) 1
• Consider sedation if time permits
• Prepare for advanced cardiac life support if deterioration occurs

Hemodynamically Stable Narrow-Complex Tachycardia

1. First-line approaches:

   • Vagal maneuvers (Valsalva, carotid sinus massage after confirming absence of carotid bruit) 1
   • IV adenosine (6mg rapid bolus, may repeat with 12mg if ineffective) 1
   • IV verapamil or diltiazem (calcium channel blockers) 1

2. Second-line approaches:

   • IV beta-blockers (esmolol, metoprolol) 1
   • Synchronized cardioversion if pharmacological therapy fails 1

3. For atrial fibrillation specifically:

   • Rate control: Beta-blockers or diltiazem are first-line 1
   • Rhythm control: Consider ibutilide, dofetilide, flecainide, or amiodarone 1
   • Digoxin and amiodarone may be used in patients with heart failure 1

Hemodynamically Stable Wide-Complex Tachycardia

1. Monomorphic VT:

   • Without heart failure or AMI: IV procainamide (10 mg/kg) 1, 2
   • With heart failure or AMI: IV amiodarone (150 mg over 10 min, followed by infusion) 1, 2, 3
   • Sotalol may be considered for stable sustained monomorphic VT 1

2. Polymorphic VT:

   • With long QT syndrome: IV magnesium, pacing, beta-blockers 1
   • Without long QT syndrome: IV beta-blockers (for ischemic or catecholaminergic VT) 1
   • With acquired long QT: IV magnesium, consider pacing or isoproterenol if bradycardia present 1

3. Undifferentiated stable wide-complex tachycardia:

   • IV adenosine may help diagnose the underlying rhythm 1
   • If diagnosis remains unclear, treat as VT 2

Special Considerations

Ventricular Tachycardia Storm

• Correct reversible causes (electrolyte abnormalities, ischemia, drug toxicity) 2
• High-dose beta-blockers (propranolol more effective than metoprolol) 2
• Consider combining beta-blockers with amiodarone for recurrent episodes 2
• Maintain potassium >4.0 mEq/L and magnesium >2.0 mg/dL 2
• Consider urgent coronary revascularization if evidence of acute ischemia 2
• For refractory cases, consider catheter ablation 2, 4

Pregnancy

• Electrical cardioversion is safe at all stages of pregnancy for unstable patients 5
• For stable SVT, vagal maneuvers followed by adenosine are preferred 5
• For stable VT, ajmaline, procainamide, or lidocaine can be used 5

Long-term Management

• Implantable cardioverter-defibrillator (ICD) for patients with structural heart disease and sustained VT/VF 6
• Radiofrequency catheter ablation for:
  • Idiopathic VT (structurally normal heart) 6
  • Atrial tachycardia (success rates 80-95%) 7
  • Refractory cases of SVT 1
• Antiarrhythmic drugs for long-term suppression based on underlying cardiac substrate 6

Common Pitfalls to Avoid

1. Failing to identify and treat underlying causes (ischemia, electrolyte abnormalities, thyroid disorders)
2. Administering verapamil or diltiazem in wide-complex tachycardias of uncertain origin (can precipitate hemodynamic collapse in VT)
3. Using digoxin for chemical cardioversion of atrial fibrillation (ineffective)
4. Delaying electrical cardioversion in unstable patients
5. Not maintaining adequate electrolyte levels during treatment (especially potassium and magnesium)
6. Failing to consider expert consultation for complex or refractory cases

Remember that the specific treatment approach should be guided by the type of tachycardia, hemodynamic status, and underlying cardiac condition, with immediate electrical cardioversion being essential for any unstable patient.