17 BBB

  • AP can only go from SA to ventricle from AV node
  • PR: electrical activity pass through all these things before ventricular depolarize

  • severe block: does not generate QRS, does not conduct to ventricle

  • symptoms: low CO

  • can be caused by any portion of AV conduction system
  • clinically divided into two causes

  • AV node: fewer dropped beats, less bradycardia, improve with exertion (increased sympathetic activity)

  • type 1: no dropped beats

1st Degree

  • should be under 1 box
  • all followed by QRS
  • AV node: good prognosis
  • atheletes: high parasympathetic tone
  • no symptoms for condition. All P conducted, no bradycardia

  • fibrosis: occurs with aging. Older pts have advanced types of AV block, pacemaker

2nd Degree

Mobitz 1

  • like 1st degree, but gets worse with each beat until no conduction
  • find non-conducted P, find one before and one after, see length differences

  • BB, CCB, atheletes
  • regularly irregular pulse, different from afib
  • asymptomatic, goes away with exertion

  • different lengthed PR
  • grouped beating
  • irregular RR interval

  • fibrosis: occurs with aging. Older pts have advanced types of AV block, pacemaker

Mobitz II

  • no progressive prolongation: 2 conducted P, same length, then 2 non conducted P
  • HIS purkinje: hanging on barely, can conduct 2, then can't conduct for next 2
  • high risk to complete heart block
  • often with BBB: HIS purkinje includes BB, wide QRS

3rd Degree

  • no conduction from A to V
  • some lower rate pacemaker in AV or V depolarizing the V at slower rate
  • may look similar to Mobitz type 1, difference: RR interval completely regular

stage 2:

  • heart shield: Heart block caused by Myocarditis
  • bells on both side: Bilateral Bell's palsy

AV Dissociation

  • AV dissociation but still has P, not caused by AV block

  • escape rhythm generated by lower pacemaker
  • lower pacemaker cannot increase rate like SA

Pacemaker

BBB

  • when AP reach BB, one is not blocked, starts QRS on time (normal PR) but take longer to depolarize (wide QRS)

  • RBBB: V1 pointing up
  • LBBB: V1 pointing down

  • RBBB: impulse travels to left, depolarize, then send electricity slowly to RV, takes longer, thus prolonged QRS

  • LBBB: electrical activity go towards left, away from V1, negative V1
  • RBBB: go towards right, towards V1, positive V1
  • result: different QRS

  • rSR': rabbit ears

  • underlying structural problems that may cause problems
  • biggest problem: interfere with ischemia detection

  • underlying diseases that can result in BBB