Bundle Branch Blocks

    .

    Right Bundle Branch Block

    • Criteria:
      • AHA Criteria for RBBB (2009):  

        (MANDATORY #1-3.  #4 is conditional)

         

        1.  QRS > 120 ms in adults (>100 ms in children  4-16yo, and > 90 ms <4yo

        2.  Leads V1 or V2:

        • rsr' , rsR' , or rSR' pattern
        • The R  or r  deflection is usually wider than the initial R wave.
        • A wide and notched R wave pattern may be seen in lead V1 and/or V2.

        3.  Leads 1 and V6:

        • S > R in duration OR >40 ms in leads I and V6 in adults.

        4.  R-wave Peak Time
        (
        When a pure dominant R wave with or without a notch is present in V1)

        • Normal in V5/6, but >50 ms in V1
    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

     

    RBBB_Display4.png

     

    Incomplete Right Bundle Branch Block 

    • Criteria:
      • AHA Criteria for Incomplete RBBB (2009):  

         

        1.  Same criteria as RBBB except:

             QRS 110-120ms (adults)

         

    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

    Left Bundle Branch Block

     

    • AHA 2009 Guidelines for Left Bundle Branch Block:

       

      1.  QRS ≥ 120ms in adults (>100ms children 4-16, >90ms children <4yo)

      2.  Lateral Leads (I, aVL, V5, V6)

          a.)  Broad notched/slurred R-wave in LATERAL leads (I, aVL, V5, V6)

           (Sometimes V5-6 can have RS pattern, due to displaced transition of QRS)

          b.) Absent q-waves in LATERAL LEADS (I, V5, V6)   (aVL may have q)

          c.) R-wave peak-time WIDE in LATERAL  > 60ms in V5-6 (Normal in V1-3)

      3.  ST and T-waves usually opposite direction of QRS

            - Positive concordance can be normal (Positive T-wave in leads with upright QRS)

            - NOTE: Negative concordance is abnormal.  (Depressed ST or T-waves in leads with negative QRS)

      4.  Axis Deviation can be RIGHT, LEFT, or SUPERIOR

     

    • NOTE: Usually lateral Q-waves represent fast (L-->R) septal depolarization (which is reversed in a LBBB)
    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

     

    LBBB3.png

     

    Incomplete Left Bundle Branch Block

    • AHA Criteria for Incomlpete RBBB
      1.  QRS 110 - 119ms  (90 - 100ms in children 8-16yo, and 80-90ms in children <8yo)
      2.  LVH Criteria Met
      3.  R-wave Peak Time > 60ms
      4.  No Q-waves in lateral leads: I, V5, and V6
    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

     

    • Example of Incomplete LBBB:
    • incompleteLBBB.png

    Left Anterior Fascicular Block

     

    • lafbAxis.png

      AHA 2009 Guidelines for Left Anterior Fascicular Block

       

      1.  Left Axis Deviation (-45° and -90°)

      2.  qR pattern in lead aVL.
      3.  R-peak time in lead aVL ≥45 ms.

      4.  QRS < 120 ms.

      Do not apply to patients with congenital heart disease with LAD since infancy. 

     

     

    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

     

     

     

    LAFB-Example.png

     

    Left Posterior Fascicular Block

     

    • Left Posterior Fascicular Block Criteria (AHA 2009)

       

      1.  Axis 90° to 180°  

      (Children up to 16 have more rightward axis, this criterion should only be applied to them when a distinct rightward change in axis is documented)

      2. rS pattern in leads I and aVL.

      3. qR pattern in leads III and aVF.

      4. QRS duration < 120 ms

       

    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC53(11)

     

    Nonspecific Intraventricular Conduction Delay

    • Nonspecific or Unspecified Intraventricular Conduction Disturbance DEFINITION:

      • QRS > 110ms
      • Does not meet criteria for LBBB or RBBB
        OR
      • Limb leads have LBBB pattern and precordial limbs have RBBB pattern (or vice versa)

       

     

    • Reference: Surawicz (2009) "AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram", JACC, 53(11)
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