16 February 2025
: Case report 
Right Bundle Branch Block on ECG as a Predictor of Sudden Cardiac Arrest Due to Pulmonary Embolism
Unusual clinical course, Challenging differential diagnosis, Management of emergency care
Chunliang Wang
ACE 1*, Yuzhu Fan BDE 2, Guiting Liang BC 2, Yu Chen BC 3, Ping Wang BE 4
DOI: 10.12659/AJCR.946074
Am J Case Rep 2025; 26:e946074
Figure 4. (A) Normal QRS complex in the horizontal plane. (B) When the RV becomes dilated due to pulmonary embolism, the horizontal plane QRS axis rotates clockwise and the terminal vector points to the right. As a result, a second R wave arises in V1, which indicates RBBB. (C) When RV dilation worsens significantly, the horizontal plane QRS axis further rotates and the initial vector moves away from the position of V1. As a result, the first R wave of RBBB disappears in V1, and eventually a QR pattern presents in V1. RV – right ventricle; RBBB – right bundle branch block; Vi – initial vector; Vm – main vector; Vt – terminal vector.