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3.21

Novacode 3.2: complete right bundle branch block — QRS ≥ 120 ms, rSR′ in V1–V2, wide S in I and V6; when it is benign and when it needs evaluation.

Code 3.21 (Novacode NC-3.2) — complete right bundle branch block (RBBB). In RBBB the impulse does not pass down the right bundle branch. The left ventricle is activated normally and the right ventricle is activated late, through the muscle. This produces a wide QRS (≥ 120 ms) with a characteristic rSR′ ("M") pattern in V1–V2 and a broad S wave in leads I and V6. In the Minnesota Code the same finding is coded 7-2-1.

Novacode 3Ventricular conductionRight bundle branch block

QRS duration≥ 120 ms

V1–V2rsr′, rsR′ or rSR′

I and V6S wave > R or > 40 ms

Minnesota Code7-2-1

ECG criteria (AHA/ACCF/HRS)

QRS duration ≥ 120 ms in adults
rsr′, rsR′ or rSR′ in V1 or V2; the R′ is usually wider than the initial R wave. Sometimes a wide, notched R wave is seen instead
S wave in leads I and V6 of longer duration than the R wave or > 40 ms
R-peak time > 50 ms in V1, normal R-peak time in V5 and V6
Secondary ST depression and T-wave inversion in V1–V3 are expected

When the morphology is the same but the QRS is 110–119 ms, the finding is called incomplete RBBB; it is common in healthy people and usually harmless.

Figure 1. Left: normal V1 (rS). Right: complete RBBB — QRS ≥ 120 ms, rSR′ ('rabbit ears') pattern in V1 and secondary T inversion.

Causes

Often found in healthy people without heart disease, and its frequency increases with age
Coronary artery disease, hypertension, cardiomyopathy, myocarditis
Right ventricular pressure or volume overload: pulmonary embolism, pulmonary hypertension, atrial septal defect
Degenerative disease of the conduction system; after heart surgery or catheter procedures
Brugada pattern can resemble RBBB (coved ST elevation in V1–V2) and needs specialist assessment

Clinical significance

Isolated RBBB in a person without symptoms and with a normal heart usually has a good prognosis. Its importance increases when it is new, when it occurs together with left anterior or posterior fascicular block (bifascicular block) or a long PR interval, or when there are signs of heart disease. A new RBBB with sudden breathlessness or chest pain may indicate acute pulmonary embolism or myocardial infarction.

Usually benign

Long-standing, isolated RBBB, no symptoms, normal echocardiogram.

Needs evaluation

New RBBB, combination with fascicular block or AV block, fainting, breathlessness, family history of sudden death.

Seek urgent care

if RBBB appears together with chest pain, sudden breathlessness, fainting or a very slow pulse.

References

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Circulation. 2009;119(10):e235–e240. doi:10.1161/CIRCULATIONAHA.108.191095
Rautaharju PM, Park LP, Chaitman BR, Rautaharju F, Zhang ZM. The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression. J Electrocardiol. 1998;31(3):157–187.
Prineas RJ, Crow RS, Zhang ZM. The Minnesota Code Manual of Electrocardiographic Findings. 2nd ed. London: Springer; 2010. doi:10.1007/978-1-84882-778-3

This article is for general information and does not replace a consultation with a doctor. ECG findings must be interpreted by a physician together with symptoms and other tests.

Published on 14 May 2019

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