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

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

Differential diagnosis:

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

Differential diagnosis:

With preexisting bundle branch block:

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

Differential diagnosis:

With preexisting bundle branch block:

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

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

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

Differential diagnosis:

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

Differential diagnosis:

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

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)

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)

Differential diagnosis:

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