AV Conduction Disorders

3.2 AV Conduction Disorders

1st Degree AV Block

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Mechanism:

  • Delay in impulse conduction at the AV node without interruption of this impulse

ECG characteristics:

  • No pause
  • Prolongation of the PQ interval > 200 ms

Etiology:

  • CHD, acute posterior myocardial infarction
  • Heart defects, hypertension, medications, CMP
  • Increased vagal tone

Treatment:

  • No treatment as a rule
  • Cessation of medications that may cause delayed conduction if applicable

1st Degree AV Block

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image

Differential diagnosis:

  • Atrial flutter with 2:1 or 3 :1 conduction
  • AV conduction delay with SVES
  • 2nd degree AV block, Mobitz type
  • Prolonged P wave with interatrial block

1st Degree AV Block

image
image

Differential diagnosis:

  • AV conduction delay with SVES
  • 2nd degree AV block, Mobitz type
  • Prolonged P wave with interatrial block

1st Degree AV Block with Complete Left Bundle Branch Block

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image

Differential diagnosis:

With preexisting bundle branch block:

  • AV conduction delay with SVES
  • 2nd or 3rd degree AV block
  • Prolonged P wave with interatrial block

1st Degree AV Block with Complete Left Bundle Branch Block

image
image

Differential diagnosis:

With preexisting bundle branch block:

  • AV conduction delay with SVES
  • 2nd or 3rd degree AV block
  • Prolonged P wave with interatrial block

2nd Degree AV Block, Wenckebach Type

image

Mechanism:

  • Single intermittent interruption of impulse conduction at the AV node
  • Blockade above the level of the bundle of His

ECG characteristics:

  • “Pause with P wave”
  • Absence of QRS complex with prolongation of the PQ interval
  • Length of pause < 2 × RR interval

Etiology:

  • CHD, acute posterior myocardial infarction
  • Heart defects, hypertension, medications, CMP
  • vagal tone

Treatment:

  • Cessation of medications that may cause delayed conduction
  • Insertion of pacemaker in symptomatic patients
  • Conservative in the event of a lack of clinics

2nd Degree AV Block, Wenckebach Type

image

Mechanism:

  • Single intermittent interruption of impulse conduction at the AV node
  • Blockade above the level of the bundle of His

ECG characteristics:

  • “Pause with P wave”
  • Absence of QRS complex with prolongation of the PQ interval
  • Length of pause < 2 × RR interval

Etiology:

  • CHD, acute posterior myocardial infarction
  • Heart defects, hypertension, medications, CMP
  • Increased vagal tone

Treatment:

  • Cessation of medications that may cause delayed conduction
  • Insertion of pacemaker in symptomatic patients
  • Conservative in the event of a lack of clinics

2nd Degree AV Block, Wenckebach Type

image
image

Differential diagnosis:

  • AV blocked SVES
  • 2nd degree AV block, Mobitz type
  • 3rd degree AV block
  • 2nd degree SA block
  • Sinus arrhythmia

2nd Degree AV Block, Wenckebach Type

image
image

Differential diagnosis:

  • AV blocked SVES
  • 2nd degree AV block, Mobitz type
  • 3rd degree AV block
  • 2nd degree SA block
  • Sinus arrhythmia

2nd Degree AV Block, 2:1 Block

image

Mechanism:

  • Intermittent interruption of impulse conduction at the AV node
  • Both blockade above and below the level of the bundle of His

ECG characteristics:

  • “Bradycardia with P waves”–only every second atrial beat is conducted to the ventricles with prolongation of the PQ interval

Etiology:

  • Heart defects, hypertension, CMP, inflammatory
  • Medications
  • CHD, acute posterior myocardial infarction

Treatment:

  • Insertion of pacemaker in the majority of patients (relative indication in asymptomatic patients)

2nd Degree AV Block, Mobitz Type

image

Mechanism:

  • Intermittent interruption of impulse conduction at the AV node
  • Blockade below the level of the bundle of His

ECG characteristics:

  • “Pause with P wave”

Single failure of conduction via the AV node without prolongation of the PQ interval

Pause = 2 × RR interval

Etiology:

  • Heart defects, hypertension, CMP, inflammatory, medications
  • CHD, acute posterior myocardial infarction

Treatment:

  • Insertion of pacemaker in the majority of patients (relative indication in asymptomatic patients)

2nd Degree AV Block, 2:1 Block

image
image

Differential diagnosis:

  • AV blocked SVES
  • 3rd degree AV block
  • 2nd degree SA block
  • Sinus arrhythmia

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Aug 29, 2016 | Posted by in CARDIOLOGY | Comments Off on AV Conduction Disorders

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