AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the ECG: Part III: Intraventricular Conduction Disturbances

Authors, Journal, Affiliations, Type, DOI

• Authors: Borys Surawicz, Rory Childers, Barbara J. Deal, Leonard S. Gettes
• Journal: Journal of the American College of Cardiology, Vol. 53, No. 11, 2009:976–81
• Affiliations: CARE Group, University of Chicago, Northwestern, University of North Carolina
• Type: Multi-society scientific statement (AHA/ACCF/HRS)
• DOI: https://doi.org/10.1016/j.jacc.2008.12.013

Overview

Part III of the AHA/ACCF/HRS ECG Standardization series, providing definitive 2009 criteria for all intraventricular conduction disturbances including complete and incomplete RBBB and LBBB, left anterior and posterior fascicular blocks, nonspecific IVCD, and WPW ventricular preexcitation — with pediatric adaptations for each. The document formally establishes that concordant negative ST-T changes in LBBB are abnormal (the AHA-endorsed basis for Sgarbossa criterion 2), standardizes frontal plane axis nomenclature, and deprecates several commonly used ECG terms including "bifascicular block," "trifascicular block," and "Brugada pattern" for automated ECG reports.

Keywords

Bundle-branch block, LBBB, RBBB, left anterior fascicular block, left posterior fascicular block, ventricular preexcitation, WPW, bifascicular block, Brugada pattern, nonspecific IVCD, QRS duration, frontal plane axis

Key Takeaways

Normal QRS Duration

• QRS duration depends on method of measurement, age, gender, and lead location
• Global intervals (earliest onset to latest offset across all leads; from spatial vector magnitude or superimposed complexes) are the preferred standard — longer than single-lead measurements
• QRS complex is wider in precordial than limb leads; may increase with increasing heart size
• Adult males: range 74–114 ms, average 95 ms; up to 110 ms considered normal
• Adults and children >16 years: QRS duration >110 ms = abnormal
• Children 4–16 years: ≥100 ms = prolonged
• Children <4 years: ≥90 ms = prolonged

Mean Frontal Plane QRS Axis

• Marked LAD (−45° to −90°) often associated with left anterior fascicular block
• Marked RAD (120°–180°) often associated with left posterior fascicular block
• In children: normal rightward axis at birth shifts gradually leftward throughout childhood
• Leftward axis shifts in CHD with underdeveloped RV (tricuspid atresia) or abnormal conduction system location (complete AV septal defect)

Complete RBBB

Four criteria; first three must be present; criterion 4 required only when pure dominant R wave (±notch) is present in V1:

1. QRS ≥120 ms (adults); >100 ms (children 4–16 yr); >90 ms (children <4 yr)
2. rsr', rsR', or rSR' in V1 or V2 — R' or r' usually wider than initial R wave; in minority, wide notched R wave in V1/V2
3. S wave of longer duration than R wave, or >40 ms, in leads I and V6
4. Normal R-peak time in V5 and V6 but >50 ms in V1

Incomplete RBBB

• QRS 110–120 ms (adults); 90–100 ms (children 4–16 yr); 86–90 ms (children <8 yr)
• All other morphologic criteria same as complete RBBB
• In children: incomplete RBBB diagnosed when terminal rightward deflection is 20–40 ms
• rsr' in V1/V2 with normal QRS duration is a normal variant in children
• Terms "rsr'" and "normal rsr'" are not recommended (variable interpretation)

Complete LBBB

Eight criteria — first six are core morphologic/duration criteria; criteria 7 and 8 address ST-T changes and axis:

1. QRS ≥120 ms (adults); >100 ms (children 4–16 yr); >90 ms (<4 yr)
2. Broad notched or slurred R wave in leads I, aVL, V5, V6 — occasional RS pattern in V5/V6 attributed to displaced QRS transition
3. Absent q waves in I, V5, V6 — narrow q wave in aVL may be present without myocardial pathology
4. R-peak time >60 ms in V5 and V6, but normal in V1/V2/V3 when small initial r waves can be discerned
5. ST and T waves usually opposite in direction to QRS (secondary ST-T changes)
6. Positive T wave in leads with upright QRS may be normal (positive concordance is acceptable)
7. Depressed ST segment and/or negative T wave in leads with negative QRS (negative concordance) are ABNORMAL — this is the AHA-endorsed basis for Sgarbossa concordant criteria (criteria 1 and 2); discussed further in Part VI of this series
8. LBBB may change mean QRS axis in frontal plane to right, left, or superior — sometimes rate-dependent

Incomplete LBBB

1. QRS 110–119 ms (adults); 90–100 ms (children 8–16 yr); 80–90 ms (<8 yr)
2. Presence of LVH pattern
3. R-peak time >60 ms in V4, V5, V6
4. Absence of q waves in I, V5, V6

Nonspecific Intraventricular Conduction Disturbance (IVCD)

• QRS >110 ms (adults); >90 ms (children 8–16 yr); >80 ms (<8 yr) without criteria for RBBB or LBBB
• May also be applied to a pattern with RBBB criteria in precordial leads and LBBB criteria in limb leads, or vice versa

Left Anterior Fascicular Block (LAFB)

1. Frontal plane axis −45° to −90°
2. qR pattern in lead aVL
3. R-peak time in aVL ≥45 ms
4. QRS duration <120 ms

• These criteria do not apply to CHD patients with congenital left axis deviation in infancy

Left Posterior Fascicular Block (LPFB)

1. Frontal plane axis +90° to +180° (adults); in children, only 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

Ventricular Preexcitation — WPW Type

Four criteria (whether preexcitation is full cannot be confirmed from surface ECG; these suggest full preexcitation):

1. PR interval <120 ms in adults; <90 ms in children (assuming no intra-atrial or interatrial conduction block)
2. Delta wave — slurring of initial QRS portion, either interrupting or immediately following P-wave termination
3. QRS >120 ms (adults); >90 ms (children)
4. Secondary ST and T-wave changes

Terms Not Recommended by AHA 2009

Additional Terms Recommended

• "Possible peri-infarction block": When an abnormal Q wave from MI in inferior/lateral leads is accompanied by a wide terminal QRS deflection directed opposite to the Q wave (i.e., QR complex in inferior/lateral leads)
• "Peri-ischemic block": A transient increase in QRS duration that accompanies ST-segment deviation in the setting of acute ischemic injury

Limitations of the Document

• Published 2009; QRS normal-range data described as "still evolving" at time of publication; values may require revision as global race/age/sex data accumulate
• Pediatric criteria for QRS duration based on 1980 Davignon standards; higher digital sampling rates (500–1200 samples/sec) may alter normal limits
• WPW criteria specify "suggestive of full preexcitation" — degree of preexcitation cannot be determined from surface ECG
• Deprecation of "bifascicular" and "trifascicular" terminology has not been universally adopted in clinical practice despite this AHA recommendation

Key Concepts Mentioned

• concepts/ECG-Conduction-Disturbances — formal IVCD criteria; all block definitions; deprecated terms
• concepts/Sgarbossa-Criteria — AHA 2009 LBBB criterion 7 is the explicit basis for Sgarbossa concordant criteria
• concepts/ST-T-Changes — secondary ST-T changes in LBBB; concordance principles
• concepts/ECG-Ventricular-Hypertrophy — incomplete LBBB criterion 2 requires LVH pattern

Key Entities Mentioned

• entities/Brugada-Syndrome — "Brugada pattern" deprecated in automated algorithms; 3 distinct ECG subtypes

Wiki Pages Updated

• wiki/sources/ecg-bbb-aha-2009.md — created
• wiki/concepts/ECG-Conduction-Disturbances.md — created
• wiki/concepts/Sgarbossa-Criteria.md — AHA 2009 LBBB criterion 7 as formal basis added; source count 1→2
• wiki/concepts/ST-T-Changes.md — cross-reference to ECG-Conduction-Disturbances added; source count 6→7
• wiki/sourceindex.md — new entry added
• wiki/wikiindex.md — ECG-Conduction-Disturbances entry added; Sgarbossa-Criteria description updated