What is the management of ventricular tachycardia (VT) with a right bundle branch block (RBBB) morphology?

Management of Ventricular Tachycardia with RBBB Morphology

For ventricular tachycardia with RBBB morphology, direct current cardioversion is recommended as first-line treatment in hemodynamically unstable patients, while intravenous verapamil or beta-blockers should be administered in hemodynamically stable patients with LV fascicular VT. 1

Diagnosis and Classification

Before initiating treatment, it's crucial to correctly identify VT with RBBB morphology:

• RBBB morphology in VT is characterized by a QRS width >0.14 seconds 1
• VT with RBBB morphology can originate from:
  • Left ventricle (most common)
  • Right ventricle (particularly in ARVC where 62% of RBBB VTs actually originate from RV) 2
  • His-Purkinje system (bundle branch reentrant VT)
  • Left ventricular fascicles (fascicular VT)

Key Diagnostic Features

• QRS duration >0.14 seconds with RBBB pattern
• RS interval >100 ms in any precordial lead (highly suggestive of VT)
• Presence of fusion beats or AV dissociation strongly indicates VT
• In fascicular VT: RBBB morphology with left axis deviation 1

Management Algorithm

1. Assess Hemodynamic Stability

If Hemodynamically Unstable:

• Immediate direct current cardioversion (Class I recommendation) 1
• For patients who are hypotensive but conscious, provide sedation before cardioversion

If Hemodynamically Stable:

A. For LV Fascicular VT (RBBB with left axis deviation):

• First-line: IV verapamil or beta-blockers 1

B. For other RBBB morphology VTs:

• First-line: Electrical cardioversion 1
• Alternative pharmacological options:
  • IV amiodarone (preferred in patients with heart failure or suspected ischemia) 1, 3
  • IV procainamide or flecainide (for patients without severe heart failure or acute MI) 1
  • IV lidocaine (only moderately effective) 1

2. Post-Acute Management

• For bundle branch reentrant VT:

  • Catheter ablation of the right bundle branch (highly effective) 4

• For scar-related VT:

  • Urgent catheter ablation is recommended for incessant VT or electrical storm (Class I) 1
  • Catheter ablation is recommended for recurrent ICD shocks due to sustained VT (Class I) 1
  • Consider catheter ablation after first episode of sustained VT in patients with ICD (Class IIa) 1

• For idiopathic VT:

  • Catheter ablation is first-line for symptomatic idiopathic left VTs 1
  • Beta-blockers, verapamil, or sodium channel blockers for symptomatic patients when ablation is unavailable 1

Special Considerations

1. RBBB VT in ARVC: Contrary to traditional teaching, RBBB morphology VT in ARVC more commonly originates from the RV (62%) rather than LV 2. Early precordial transition (V2 or V3) with superior axis suggests RV origin.

2. Bundle Branch Reentrant VT: Can present with either LBBB or RBBB morphology, and rarely both morphologies can occur in the same patient 5. Usually occurs in patients with structural heart disease and conduction system disease.

3. Bidirectional VT: Can occur with RBBB or LBBB configuration and is characterized by beat-to-beat alternans in QRS frontal plane axis 1, 6.

Pitfalls to Avoid

1. Misdiagnosis: Wide-complex tachycardias are often misdiagnosed. When in doubt, treat as VT.

2. Assuming chamber of origin based solely on morphology: RBBB morphology doesn't always indicate LV origin, especially in ARVC 2.

3. Inappropriate medication use: Avoid verapamil in patients with VT unless certain it's fascicular VT, as it can cause hemodynamic collapse in other forms of VT.

4. Delayed cardioversion: In hemodynamically unstable patients, immediate cardioversion is essential rather than attempting pharmacological conversion.

By following this approach, you can effectively manage patients with VT demonstrating RBBB morphology while minimizing morbidity and mortality.