RBBB

Again, watch V1. In right bundle branch block (RBBB) the conduction in the bundle to the right ventricle is slow. As the right ventricles depolarizes, the left ventricle is often halfway finished and few counteracting electrical activity is left. The last electrical activity is thus to the right, or towards lead V1. In RBBB the QRS complex in V1 is allways markedly positive.

Right bundle branch block (RBBB) in lead V1

A 12 lead ECG with right bundle branch block (and left atrial enlargement)

Criteria for right bundle branch block (RBBB) [1]

QRS >0,12 sec

Slurred S wave in lead I and V6

RSR'-pattern in V1 where R' > R

Diagnosing myocardial infarction in RBBB is not as difficult as in LBBB.