Ventricular Conduction Disturbances

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Ventricular Conduction Disturbances

• Chapter 7

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Bundle Branches

• Normal conduction speed through the bundles is
  about 0.1 seconds.

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Bundle Branch Block

• Consider a blocked or slowed branch or bundle

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Right Bundle Branch Block
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Right Bundle Branch Block
First Phase - Normal
Second Phase - Normal
Third Phase - ?
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Right Bundle Branch Block
V1 rSR
V6 qRS
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Right Bundle Branch Block
V1 rSR?
V6 qRS
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Right Bundle Branch Block

• V1 or V2 rSR
• M or rabbit ear shape
• V5 or V6 qRS
• Right chest leads T wave inversion (secondary
  changes since they reflect a delay in
  depolarization not an actual change in
  depolarization).
• Complete RBBB QRS gt 0.12 sec.
• Incomplete RBBB QRS 0.10 to 0.12 sec.

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Right Bundle Branch Block

• Clinical Significance
• Normal
• Organic heart disease
• atrial septal defect
• pulmonary disease
• valvular lesions
• degenerative changes in conduction system
• chronic coronary artery disease
• pulmonary embolism
• after bypass graft surgery
• Permanent or transient
• RBBB by itself requires no treatment

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Left Bundle Branch Block

• RBBB affects mainly the terminal phase of
  depolarization
• LBBB affects also affects the early phase of
  depolarization

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Left Bundle Branch Block
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Left Bundle Branch Block

• Wide QRS
• Note loss of septal R in V1 and septal Q in V6.

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Left Bundle Branch Block

• Wide QRS complex
• V1 may have a W shape to it.
• V6 may show a M shape or rabbit ears
• Secondary T wave inversion
• Secondary if in lead with tall R waves
• Primary is in right precordial leads

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Left Bundle Branch Block
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RBBB versus LBBB
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Interventricular Delay
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Left Bundle Branch Block

• Organic disease
• long standing hypertension
• valvular lesion
• cardiomyopathy
• coronary artery disease

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Pacemaker Pattern
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Trifascicular Conduction System
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Trifascicular Conduction System

• Block in right bundle
• Block in left bundle
• block in the left anterior fascicle
• block in the left posterior fascicle
• Hemiblock or Fascicular block

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Left Anterior Fascicular Block

• Limb leads
• QRS less width less than 0.12 sec.
• QRS axis -45 or more

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Left Posterior Fascicular Block

• QRS axis 120 or more
• Need to rule out other causes of RAD
• Rare

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