Second degree AV block type I: Difference between revisions

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==Background==
==Background==
[[File:Second degree heart block.png|thumb|Types of second degree AV block]]
*Also known as a Mobitz I or Wenkebach AV block
*Also known as a Mobitz I or Wenkebach AV block
*Disturbance of atrial impulse conducting through the AV node
*Disturbance of atrial impulse conducting through the AV node
*Considered more benign than Mobitz II as it is not associated with histological changes


==Clinical Features==
==Clinical Features==
 
*Usually asymptomatic
*Those who are symptomatic may present with:
**[[Dizziness|Lightheadedness/dizziness]]
**Presyncope or [[syncope]]


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
*[[ECG]]: ''progressive prolongation of PR interval'' with subsequent beat not reaching the ventricle
===Workup===
*[[ECG]]
 
===Diagnosis===
[[File:Type I A-V block 5-to-4 Wenckebach periods.png|thumb|Type I A-V block (5:4) with acute inferior infarction]]
*[[ECG]] with:
**Progressive prolongation of PR interval on consecutive beats
**Dropped QRS beat not conducted to ventricle after maximal PR prolongation
**After dropped QRS complex, PR interval resets and again begins the cycle of progressive prolongation


==Management==
==Management==
 
*Generally benign condition that does not require management after ruling out [[MI]], [[drug overdose|drug toxicity]], [[electrolyte imbalance]] and other unusual causes
*Symptomatic patients can be treated with [[atropine]] or [[isoproterenol]] to transiently improve conduction or with transcutaneous or transvenous pacing if there is associated hypotension<ref> Jones, W., and Napier, L. Atrioventricular block second-degree. Statpearls. Jan 2019</ref>


==Disposition==
==Disposition==
*Generally outpatient
*Generally outpatient
*2:1 block<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>
**May be unable to determine if Type I or Type II
**If so, assume [[Second Degree AV Block Type II|type II]] and admit with cardiology consult


==See Also==
==See Also==

Latest revision as of 16:05, 26 September 2019

Background

Types of second degree AV block
  • Also known as a Mobitz I or Wenkebach AV block
  • Disturbance of atrial impulse conducting through the AV node
  • Considered more benign than Mobitz II as it is not associated with histological changes

Clinical Features

Differential Diagnosis

AV blocks

Evaluation

Workup

Diagnosis

Type I A-V block (5:4) with acute inferior infarction
  • ECG with:
    • Progressive prolongation of PR interval on consecutive beats
    • Dropped QRS beat not conducted to ventricle after maximal PR prolongation
    • After dropped QRS complex, PR interval resets and again begins the cycle of progressive prolongation

Management

  • Generally benign condition that does not require management after ruling out MI, drug toxicity, electrolyte imbalance and other unusual causes
  • Symptomatic patients can be treated with atropine or isoproterenol to transiently improve conduction or with transcutaneous or transvenous pacing if there is associated hypotension[1]

Disposition

  • Generally outpatient
  • 2:1 block[2]
    • May be unable to determine if Type I or Type II
    • If so, assume type II and admit with cardiology consult

See Also

External Links

References

  1. Jones, W., and Napier, L. Atrioventricular block second-degree. Statpearls. Jan 2019
  2. Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014. http://emedicine.medscape.com/article/161919-treatment#showall.