Conduction abnormalities
Left bundle branch block
ECG criteria
QRS ≥120 ms, broad monophasic R in I, V5-V6, deep S in V1-V2.
Related: conduction abnormalities
- 1st degree AV blockPR interval >200 ms, every P followed by QRS.
- 2nd degree AV block Mobitz I (Wenckebach)Progressive PR prolongation until a non-conducted P wave.
- 2nd degree AV block Mobitz IIConstant PR with intermittent non-conducted P waves; often wide QRS.
- Complete AV blockAtrial and ventricular activity completely dissociated.
- Right bundle branch blockQRS ≥120 ms, rsR' in V1-V2, wide S in I and V6.
- Left anterior fascicular blockLeft axis deviation (-45 to -90), qR in I and aVL, rS in II/III/aVF.