Right Bundle Branch Block
Criteria
- QRS > 120 ms in adults (>100 ms in children 4-16yo, and > 90 ms <4yo
- 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.
- Leads 1 and V6: S > R in duration OR >40 ms in leads I and V6 in adults.
- 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
Examples
Left Bundle Branch Block
Criteria
- QRS ≥ 120ms in adults (>100ms children 4-16, >90ms children <4yo)
- Lateral Leads (I, aVL, V5, V6)
- 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)
- Absent q-waves in LATERAL LEADS (I, V5, V6) (aVL may have q)
- R-wave peak-time WIDE in LATERAL > 60ms in V5-6 (Normal in V1-3)
- 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)
- Axis Deviation can be RIGHT, LEFT, or SUPERIOR
Examples
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.Left Anterior Fascicular Block
Criteria
- Left Axis Deviation (-45° and -90°)
- qR pattern in lead aVL.
- R-peak time in lead aVL ≥45 ms.
- QRS < 120 ms.
Examples
Left Posterior Fascicular Block
Criteria
- Axis 90° to 180°
- rS pattern in leads I and aVL.
- qR pattern in leads III and aVF.
- QRS duration < 120 ms
Examples
Incomplete Left Bundle Branch Block
Criteria
- Same criteria as RBBB except: QRS 110-120ms (adultsL
Nonspecific Intraventricular Conduction Delay
Criteria
- 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
Further Reading
- Surawicz B, Childers R, Deal BJ, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Journal of the American College of Cardiology. 2009; 53(11):976-81.