see also: [[Left Bundle Branch Block|LBBB]] see: [EM Cases | ECG cases 12: RBBB + Occlusion MI](cubox://card?id=7240317145312134460) > [!key points] > - Do not need to use sgarbossa for evaluating STEMI in RBBB > - ST elevation is NOT normal in RBBB > [!tip]+ RBBB Diagnostic criteria > - **QRS duration > 120ms** > - **RSR’ pattern in V1-3** (“M-shaped” QRS complex) with (appropriate) discordant T wave changes > - **Wide, slurred S wave in lateral leads** (I, aVL, V5-6) > ![[Pasted image 20230516182606.png]] Associated features: - Appropriate discordance with ST depression and/or T-wave inversion in right precordial leads (V1-3). # Causes - right ventricular hypertrophy / cor pulmonale from COPD - [[Pulmonary Embolism]] - ischaemic heart disease - ==new RBBB and LAFB associated with proximal LAD occlusion== - myocarditis - cardiomyopathy - atrial septal defect # electrophysiology **Sequence of conduction in RBBB:** 1) Left ventricular activation via the left bundle (black arrow) occurs normally 2) Septal depolarisation (yellow arrows) is thus unaffected, producing a normal early QRS complex 3) Activation of the RV originates across the septum. The resultant depolarisation vector (red arrow) produces delayed R waves in leads V1-3, and S waves in lateral leads ![[Pasted image 20230516183045.png]]