Trifascicular Block

Background

• Conduction disease of all three fascicles: fight bundle branch, and left posterior and left anterior fascicles
• Trifascicular blocks can deteriorate into high grade blocks

Clinical Features

• ECG will show a bifascicular block and a prolonged PR interval

Differential Diagnosis

Differential includes ischemic events, electrolyte abnormalities, and medication overdoses in addition to rheumatologic conditions

• Anterior MI
• Rheumatic fever
• Myocarditis
• Lyme disease
• Lenegre's disease
• Lev's disease
• SLE
• Systemic sclerosis
• Amyloidosis
• Hemochromatosis
• Sarcoidosis
• Hyperkalemia
• Toxicology
  • Beta blocker toxicity
  • Calcium channel blocker toxicity
  • Digoxin toxicity
  • Amiodarone

Types of second degree AV block

AV blocks

• First degree AV block
• Second degree
  • Second degree AV block type I (Wenkebach)
  • Second degree AV block type II
• Third degree AV block
• AV dissociation without complete heart block

Bundle and Fascicular Blocks

• Right Bundle Branch Block
• Left Bundle Branch Block
• Left Anterior Fascicular Block
• Left Posterior Fascicular Block
• Trifascicular Block

Premature Beats

• Premature atrial contraction
• Premature junctional complex
• Premature ventricular contraction

Disposition

• Symptomatic patients should be admitted for monitoring and evaluation for a permanent pacemaker
• Cardiology consult