Second degree AV block type II

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Types of second degree AV block
  • A disturbance of atrial impulse conduction, usually in the distal conduction system[1]
  • Often associated with structural heart disease
  • Significant risk of hemodynamic instability, symptomatic bradycardia, and decompensation into Third Degree AV Block and subsequent cardiac arrest
    • Risk of asystole 35% per year[2]

Clinical Features

Differential Diagnosis

Differential includes ischemic events, electrolyte abnormalities, and medication overdoses in addition to rheumatologic conditions[3][4]

Types of second degree AV block

AV blocks

Bundle and Fascicular Blocks

Premature Beats


2nd degree AV Block Type 2 (4:3 conduction)
2nd degree AVB, 2:1 conduction, LBBB with buried p-waves in t-waves


  • Evaluate for underlying pathology
  • ECG
  • Labs


  • ECG findings:
    • Fixed PR interval for conducted QRS complexes
    • Intermittent non-conducted P-waves
    • P waves march through (beware of p-waves consistently buried in T-waves)



  • Admission for pacing and monitoring
  • Subsequent permanent pacemaker
  • 2:1[5] and 3:1 blocks

See Also


  1. Jones, W., and Napier, L. Atrioventricular block second-degree. Statpearls. Jan 2019
  2. Burns E. AV Block: 2nd degree, Mobitz II. Life in the Fast Lane.
  3. Hampton, JR. The ECG in Practice (5th edition), Churchill Livingstone 2008.
  4. Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.
  5. 5.0 5.1 Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014.