Second degree AV block type II: Difference between revisions

 
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==Background==
==Background==
[[File:Second degree type 2.JPG|thumbnail|2nd degree AV Block Type 2 (4:3 conduction)]]
[[File:Second degree heart block.png|thumb|Types of second degree AV block]]
*A disturbance of atrial impulse conduction through the AV node
*A disturbance of atrial impulse conduction, usually in the distal conduction system<ref>Jones, W., and Napier, L. Atrioventricular block second-degree. Statpearls. Jan 2019</ref>
*Significant risk of hemodynamic instability, symptomatic bradycardia, and decompensation into [[Third Degree AV Block]]
*Often associated with structural heart disease
*Risk of asystole 35% per year<ref>Burns E. AV Block: 2nd degree, Mobitz II. Life in the Fast Lane. http://lifeinthefastlane.com/ecg-library/basics/mobitz-2/.</ref>
*Significant risk of hemodynamic instability, symptomatic bradycardia, and decompensation into [[Third Degree AV Block]] and subsequent cardiac arrest
**Risk of asystole 35% per year<ref>Burns E. AV Block: 2nd degree, Mobitz II. Life in the Fast Lane. http://lifeinthefastlane.com/ecg-library/basics/mobitz-2/.</ref>


==Clinical Features==
==Clinical Features==
*Most patients are asymptomatic
*Most patients are asymptomatic
*[[Chest pain]]
*Symptomatic patients may present with:
*[[Hypotension]]
**[[Chest pain]]
*[[Bradycardia]]
**[[Hypotension]]
*[[Altered mental status]]
**[[Bradycardia]]
*[[Syncope]], weakness
**[[Altered mental status]]
**[[Syncope]], [[weakness]]


==Differential Diagnosis<ref>Hampton, JR. The ECG in Practice (5th edition), Churchill Livingstone 2008.</ref><ref>Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.</ref>==
==Differential Diagnosis==
*Anterior [[MI]]
{{Heart block DDX}}
*[[Rheumatic fever]]
*[[Myocarditis]]
*[[Lyme disease]]
*[[Lenegre's disease]]
*[[Lev's disease]]
*[[SLE]]
*[[Systemic sclerosis]]
*[[Amyloidosis]]
*[[Hemachromatosis]]
*[[Sarcoidosis]]
*[[Hyperkalemia]]
*[[Toxicology]]
**[[Beta blocker toxicity]]
**[[Calcium channel blocker toxicity]]
**[[Digoxin toxicity]]
**[[Amiodarone]]
 
{{AV block types}}


==Evaluation==
==Evaluation==
[[File:Type 2 - buried p wave.JPG|thumbnail|2nd degree AVB, 2:1 conduction, LBBB with buried p-waves in t-waves]]
{{Heart block evaluation workup}}
*[[ECG]] findings
===Diagnosis===
*[[ECG]] findings:
**Fixed PR interval for conducted QRS complexes
**Fixed PR interval for conducted QRS complexes
**Intermittent non-conducted P-waves
**Intermittent non-conducted P-waves
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==Management==
==Management==
*Standard [[ACLS guidelines for bradycardia]] to include<ref name="Sovari">Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014. http://emedicine.medscape.com/article/161919-treatment#showall.</ref>
*If symptomatic, standard [[ACLS guidelines for symptomatic bradycardia]] includes<ref name="Sovari">Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014. http://emedicine.medscape.com/article/161919-treatment#showall.</ref>
**[[Atropine]] 0.5mg IV q3-5min prn
**[[Atropine]] 0.5mg IV q3-5min PRN
**[[Transcutaneous pacing]], followed by [[transvenous pacing]]
**[[Transcutaneous pacing]], followed by [[transvenous pacing]]
*Treat underlying etiology
*Treat underlying etiology
*Avoid AV nodal blocking agents (e.g. [[beta blockers]])
*Avoid AV nodal blocking agents (e.g. [[β-blockers]])


==Disposition==
==Disposition==

Latest revision as of 15:21, 21 December 2020

Background

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

Evaluation

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

Workup

  • Evaluate for underlying pathology
  • ECG
  • Labs

Diagnosis

  • 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)

Management

Disposition

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

See Also

References

  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. http://lifeinthefastlane.com/ecg-library/basics/mobitz-2/.
  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. http://emedicine.medscape.com/article/161919-treatment#showall.