View source for Second degree AV block type I

==Background==
[[File:Second degree heart block.png|thumb|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==
*Usually asymptomatic
*Those who are symptomatic may present with:
**[[Dizziness|Lightheadedness/dizziness]]
**Presyncope or [[syncope]]

==Differential Diagnosis==
{{AV block types}}

==Evaluation==
===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==
*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==
*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==
*[[AV blocks]]

==External Links==


==References==
<references/>

[[Category:Cardiology]]