If only the diagnostic criteria are used, it is: V 1 is RSR‘' type, r' >; The time limit of R and qrS is > 0.12s, and the leads V5, V6, I and AVL are QRS-type, S-wide, and ST-T is a secondary change.

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First of all, we know that the right bundle branch is much thinner than the left bundle branch, and it is easier to block, while the part of the right bundle branch responsible for excitement is located on the right side of the ventricular septum. Therefore, when the right bundle branch is blocked, the ventricle is still depolarized from left to right from the left side of the interventricular septum at 1/3, and the resultant vector is the right front, so the first R wave is formed at V 1. Then the left ventricular wall and interventricular septum began to depolarize, because the left ventricular wall was more dominant, so a vector was formed after cancellation, which was S wave on V 1 and R wave on V5. Finally, the right ventricular wall and the upper part of interventricular septum were excited, forming a comprehensive vector to the front right, R' wave on V 1 and S wave on V5, because the right bundle branch was blocked. The excitement transmitted by the sinoatrial node cannot or cannot be transmitted from the right bundle branch, but only through the ventricular muscle itself. We know that the conduction of ventricular muscle is the slowest, so it takes the longest time, so there will be the width of R' wave and the width of S wave.