EKG Rounds

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EKG Rounds

• Rebecca Burton-MacLeod
• R4, Emerg Med
• July 20th, 2006

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EKG Case
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Conduction anatomy

• AV node
• Bundle of His
• Branching bundle
• Bundle branches
• Purkinje fibers
• Myocardial cells

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Bundle branch blocks

• RBBBtransmission is delayed or fails to conduct
  along right bundle branch
• LBBBtransmission is delayed or fails to conduct
  along left bundle branch
• LAFBmost common type of intraventricular
  conduction defect
• LPFBvery rare!

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Terminology

• Bifascicular blockconduction defect in RBB and
  either LAF or LPF
• Does not include RBBB and LBBB combination, as
  this is termed 3rd degree AV block
• Trifascicular blockas above, with 1st degree AV
  block (prolonged PR)

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Conduction

• Consequence of BBB is that ventricle must await
  depolarization by opposite ventricle
• Activation proceeds on cell-to-cell basis
• Results in much slower activation along normal
  pathways

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RBBB

• Causes
• In childrensurgical repair of VSDs is most
  common cause cardiomyopathy, myocarditis, CHF,
  hereditary causes (Brugada syndrome), muscular
  dystrophy
• In adultsnormal variant, RVH or strain (ex
  PE), CAD

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RBBB PE

• What will you hear on physical examination?
• Persistently split S2

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RBBB EKG findings
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RBBB
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EKG criteria

• QRS gt0.1sec
• rSR or rR pattern in V1-3
• Wide S in leads I, V6
• May have normal axis, or right or left deviation
• Usually inverted T in V1-2, in other leads T is
  directed opposite to terminal portion of QRS

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LBBB causes

• CAD
• Cardiomyopathy
• Myocarditis
• LVH
• Anatomic malformations
• Neuromuscular disease

• Hemochromatosis
• Aortic valve endocarditis
• RHD
• Perinatal exposure to HIV-I

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LBBB PE

• What heart sound changes will you hear on
  auscultation?
• Absent or diminished S1, reverse split S2

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LBBB EKG findings
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LBBB EKG
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EKG findings

• QRS gt0.12sec
• No Q in I, aVL, V6
• Prominent QS pattern in V1 (/- small R wave)
• Tall, wide, notched R in I, aVL, V6

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LAFB

• EKG findings
• Normal QRS width
• QRS axis is from 30 to 90degrees
• Q present in I, aVL
• Major QRS direction in aVF is negative
• Slurred S wave in left precordial leads
• Late R wave in aVR (gt0.045sec)
• Terminal R in aVL is slurred

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EKG
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LPFB Ddx

• Must first exclude other causes of right axis!!!
• Cor pulmonale
• Pulmonary heart disease
• Pulmonary hypertension, etc.

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LPFB

• EKG findings
• Duration of QRS is usually normal
• Q wave present in II, III, aVF
• QRS axis is 120 to 180degrees
• S wave present at end of QRS in I and aVF

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EKG
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Tough scenarios with BBB

• RVH
• LVH
• MI

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MI ?
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MI ?
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MI ?
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Sgarbossa criteria

• STE gt1mm concordant with QRS (5pts)
• STD gt1mm in V1-3 (3pts)
• STE gt5mm discordant with QRS (2pts)
• gt3pts AMI
• Sgarbossa et al. NEJM. 1996

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EKG smorgasbord
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EKG smorgasbord contd
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EKG smorgasbord contd
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EKG smorgasbord contd
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EKG smorgasbord contd
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EKG smorgasbord contd
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Questions?