What is the management plan for a patient with Right Bundle Branch Block (RBBB) and an episode of tachycardia?

Management of Right Bundle Branch Block with an Episode of Tachycardia

Patients with Right Bundle Branch Block (RBBB) and an episode of tachycardia should undergo urgent cardiac evaluation including echocardiography to assess for structural heart disease, followed by appropriate management based on the type of tachycardia identified. 1

Initial Evaluation

Diagnostic Approach

• Determine if the tachycardia is a narrow or wide QRS complex tachycardia
• For wide QRS tachycardia with RBBB pattern:
  • Assess for VA dissociation (visible in only 30% of ventricular tachycardias) 2
  • Look for fusion complexes (pathognomonic of ventricular tachycardia) 2
  • Measure QRS width (>0.14 seconds with RBBB favors ventricular tachycardia) 2
  • Evaluate for structural heart disease with echocardiography 1

Key Diagnostic Tests

• 12-lead ECG during tachycardia and in sinus rhythm
• Echocardiography to assess for structural heart disease
• 24-48 hour continuous cardiac monitoring 1
• Laboratory evaluation including CBC and CMP with attention to electrolytes 1

Management Algorithm

1. Hemodynamically Unstable Tachycardia

• Immediate DC cardioversion regardless of QRS morphology 2

2. Hemodynamically Stable Narrow QRS Tachycardia with RBBB

• First-line: Vagal maneuvers (Valsalva, carotid massage)
• Second-line: IV adenosine (preferred due to rapid onset and short half-life)
• Alternative: Non-dihydropyridine calcium channel blockers 2

3. Hemodynamically Stable Wide QRS Tachycardia with RBBB

• If diagnosis uncertain, treat as ventricular tachycardia 2
• Consider the possibility of:
  • Supraventricular tachycardia with pre-existing RBBB
  • Bundle-branch reentry ventricular tachycardia (BBRVT) 3
  • Ventricular tachycardia from right ventricle (most common) or left ventricle 4

4. Follow-up Management

• Annual clinical evaluation with ECG for asymptomatic patients with isolated RBBB 1
• More frequent follow-up (every 3-6 months) for patients with RBBB and other conduction abnormalities 1
• Consider electrophysiology study (EPS) if:
  • Syncope and bundle branch block are present
  • Structural heart disease is identified
  • Initial workup doesn't reveal a clear cause of tachycardia 1

Special Considerations

RBBB with Structural Heart Disease

• RBBB may be a marker of underlying cardiovascular disease 1
• Consider cardiac MRI if echocardiography is inconclusive 1
• Evaluate for potential heart block in symptomatic patients 1
• Consider permanent pacing if:
  • HV interval ≥70 ms on EPS
  • Evidence of infranodal block during EPS
  • Documented intermittent high-degree AV block 1

RBBB with Pulmonary Embolism

• RBBB with a QR pattern in V1 has high positive predictive value for high-risk pulmonary embolism 5
• Consider pulmonary embolism as a cause of tachycardia, especially with sudden onset and risk factors 5

Pitfalls and Caveats

• Adenosine should be used with caution when diagnosis is unclear as it may produce VF in patients with coronary artery disease 2
• Calcium channel blockers may be effective for certain types of RBBB tachycardias but should be used cautiously as they can cause hemodynamic deterioration in ventricular tachycardia 6
• Alternating bundle branch block is a high-risk feature that may indicate underlying severe conduction system disease 1
• RBBB tachycardia may originate from either ventricle - do not assume left ventricular origin based solely on RBBB morphology 4
• Even in structurally normal hearts, BBRVT should be suspected in patients with extensive underlying His-Purkinje conduction disorders 3