ECG in RBBB

QRS duration	≥0.12 sec
Intrinsicoid deflection	>0.035 in V1 and V2 due to delayed R'
Common pattern: Posterior mid-temporal forces	qRS or qrS in I, V6; rsR' or qR in V1 - Reflects anterior initial forces, anterior and rightward terminal forces
Atypical pattern: Anterior mid-temporal forces	qRS, qrS, or RS in I, V6; rsR' or qR in V1 - Reflects anterior mid-temporal right ventricular enlargement and left anterior fascicular block
ST-T waves	ST depression and T inversion in right precordial leads, upright in left precordial and limb leads - ST-T vectors are discordant to terminal mean QRS spatial vector

Major electrocardiographic characteristics of right bundle branch block.

Data from Willems JL, Demedina EO, Bernard R, et al. J Am Coll Cardiol 1985; 5:1261.

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