Second degree AV block classification: Difference between revisions
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==Classification== | ==Classification== | ||
<ref name="KusumotoSchoenfeld2019">{{cite journal|last1=Kusumoto|first1=Fred M.|last2=Schoenfeld|first2=Mark H.|last3=Barrett|first3=Coletta|last4=Edgerton|first4=James R.|last5=Ellenbogen|first5=Kenneth A.|last6=Gold|first6=Michael R.|last7=Goldschlager|first7=Nora F.|last8=Hamilton|first8=Robert M.|last9=Joglar|first9=José A.|last10=Kim|first10=Robert J.|last11=Lee|first11=Richard|last12=Marine|first12=Joseph E.|last13=McLeod|first13=Christopher J.|last14=Oken|first14=Keith R.|last15=Patton|first15=Kristen K.|last16=Pellegrini|first16=Cara N.|last17=Selzman|first17=Kimberly A.|last18=Thompson|first18=Annemarie|last19=Varosy|first19=Paul D.|title=2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society|journal=Circulation|volume=140|issue=8|year=2019|issn=0009-7322|doi=10.1161/CIR.0000000000000628}}</ref> | |||
{| class="wikitable" | |||
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Term | |||
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Classification | |||
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Definition | |||
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| rowspan="3" |[[Atrioventricular block]] | |||
| [[First-degree atrioventricular block]] | |||
| | |||
* P waves associated with 1:1 [[atrioventricular ]] conduction | |||
* PR interval >200 ms | |||
* [[atrioventricular delay]] because no P waves are blocked | |||
|- | |||
| [[Second- degree atrioventricular block]] | |||
| | |||
* P waves with a constant rate (<100 bpm) | |||
* [[Atrioventricular conduction]] is present but not 1:1 | |||
*''' [[Mobitz type I]]''' | |||
:*P waves with a constant rate (<100 bpm) | |||
:* Presence of periodic single non conducted P wave associated with P waves before and after the non conducted P wave with inconstant PR intervals | |||
*'''[[Mobitz type II]]''' | |||
:* Presence of P waves with a constant rate (< 100 bpm) with a periodic single non conducted P wave associated with other P waves before and after the non conducted P wave with constant PR intervals (excluding 2:1 atrioventricular block) | |||
*'''2:1 [[atrioventricular block]]''' | |||
:* P waves with a constant rate (or near-constant rate because of [[ventriculophasic sinus arrhythmia]]) rate (<100 bpm), every other P wave conducts to the [[ventricles]] | |||
*'''[[Advanced]], [[high-grade]] or high-degree [[atrioventricular block]]''' | |||
:* ≥2 consecutive P waves at a constant physiologic rate that do not conduct to the [[ventricles ]] with evidence for some [[atrioventricular conduction]] | |||
|- | |||
|[[Third-degree]] [[atrioventricular block]] ([[complete heart block]]) | |||
| | |||
*No evidence of [[atrioventricular conduction]] | |||
* '''[[Vagally mediated atrioventricular block]]''' | |||
:*Any type of atrioventricular block due to increased [[parasympathetic]] tone | |||
*'''[[Infranodal block]]''' | |||
:* [[Atrioventricular conduction block]] with evidence of conduction block distal to the [[atrioventricular node]] | |||
| | |||
|} | |||
===Type 1 (Mobitz I / Wenckebach)=== | ===Type 1 (Mobitz I / Wenckebach)=== | ||
*Type 1 second degree AV block, also known as Mobitz I or Wenckebach periodicity, is almost always a disease of the [[AV node]]<ref name="pmid29493981">{{cite journal |vauthors=Mangi MA, Jones WM, Napier L |title= |journal= |volume= |issue= |pages= |date= |pmid=29493981 |doi= |url=}}</ref><ref name="pmid29083636">{{cite journal |vauthors=Kashou AH, Goyal A, Nguyen T, Chhabra L |title= |journal= |volume= |issue= |pages= |date= |pmid=29083636 |doi= |url=}}</ref>. | *Type 1 second degree AV block, also known as Mobitz I or Wenckebach periodicity, is almost always a disease of the [[AV node]]<ref name="pmid29493981">{{cite journal |vauthors=Mangi MA, Jones WM, Napier L |title= |journal= |volume= |issue= |pages= |date= |pmid=29493981 |doi= |url=}}</ref><ref name="pmid29083636">{{cite journal |vauthors=Kashou AH, Goyal A, Nguyen T, Chhabra L |title= |journal= |volume= |issue= |pages= |date= |pmid=29083636 |doi= |url=}}</ref>. | ||
Revision as of 06:47, 8 July 2021
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Second degree AV block Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Second degree AV block classification On the Web |
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American Roentgen Ray Society Images of Second degree AV block classification |
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Risk calculators and risk factors for Second degree AV block classification |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Salih, M.D., Cafer Zorkun, M.D., Ph.D. [2], Raviteja Guddeti, M.B.B.S. [3]
Overview
There are two distinct types of second degree AV block, called type 1 and type 2. The distinction is made between them because type 1 second degree heart block is considered a more benign entity than type 2 second degree heart block. The distinction between Mobitz I and II can be made only when the ratio of atrial to ventricular conduction is not 2:1, because in 2:1 conduction every other beat is conducted to the ventricle and there is no opportunity to observe the PR prolongation that defines type I and II second degree AV block.
Classification
| Term | Classification | Definition | |
|---|---|---|---|
| Atrioventricular block | First-degree atrioventricular block |
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| Second- degree atrioventricular block |
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| Third-degree atrioventricular block (complete heart block) |
|
Type 1 (Mobitz I / Wenckebach)
- Type 1 second degree AV block, also known as Mobitz I or Wenckebach periodicity, is almost always a disease of the AV node[2][3].
- Mobitz I heart block is characterized by progressive prolongation of the PR interval on the electrocardiogram (EKG) on consecutive beats followed by a blocked P wave (i.e. a 'dropped' QRS complex). After the dropped QRS complex, the PR interval resets and the cycle repeats.
- One of the baseline assumptions when determining if an individual has Mobitz I heart block is that the atrial rhythm has to be regular. If the atrial rhythm is not regular, there could be alternative explanations as to why certain P waves do not conduct to the ventricles.
- This is almost always a benign condition for which no specific treatment is needed.
Type 2 (Mobitz II)
- Type 2 second degree AV block, also known as Mobitz II is almost always a disease of the distal conduction system (His-Purkinje System).
- Although the terms infranodal block or infrahisian block are often applied to this disorder, they are not synonymous with it.
- Infranodal block and infra-Hisian block are terms which refer to the anatomic location of the block, whereas
- Mobitz II refers to an electrocardiographic pattern associated with block at these levels[4].
- Mobitz II heart block is characterized on a surface ECG by intermittently non-conducted P waves not preceded by PR prolongation and not followed by PR shortening. The medical significance of this type of AV block is that it may progress rapidly to complete heart block, in which no escape rhythm may emerge. In this case, the person may experience a Stokes-Adams attack, cardiac arrest, or sudden cardiac death. The definitive treatment for this form of AV Block is an implanted pacemaker[5][6].
Differentiating Mobitz I from Mobitz II in the Presence of a 2:1 Conduction
Likely EKG findings that help differentiate Mobitz type I from type II in the presence of a 2:1 conduction ratio include:
- Very long PR interval (> 300 msec) or narrow QRS complex - indicates the block is at the level of AV node
- Administration of atropine enhances AV nodal conduction resulting in less frequent nonconducted beats - this confirms type I Mobitz
- Mobitz I is worsened by carotid sinus massage which slows AV nodal conduction, unlike Mobitz II. Carotid sinus massage paradoxically eliminates infranodal block by slowing the sinus rate[7].
Another type of classification used to classify second degree AV block is 2:1 block and high grade block (not third degree AV block). In 2:1 block every other atrial impulse is conducted down the ventricle. Higher grade blocks (eg., 3:1) unlike third degree AV block conduct few beats down the ventricle.
References
- ↑ Kusumoto, Fred M.; Schoenfeld, Mark H.; Barrett, Coletta; Edgerton, James R.; Ellenbogen, Kenneth A.; Gold, Michael R.; Goldschlager, Nora F.; Hamilton, Robert M.; Joglar, José A.; Kim, Robert J.; Lee, Richard; Marine, Joseph E.; McLeod, Christopher J.; Oken, Keith R.; Patton, Kristen K.; Pellegrini, Cara N.; Selzman, Kimberly A.; Thompson, Annemarie; Varosy, Paul D. (2019). "2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society". Circulation. 140 (8). doi:10.1161/CIR.0000000000000628. ISSN 0009-7322.
- ↑ Mangi MA, Jones WM, Napier L. PMID 29493981. Missing or empty
|title=(help) - ↑ Kashou AH, Goyal A, Nguyen T, Chhabra L. PMID 29083636. Missing or empty
|title=(help) - ↑ Li X, Xue Y, Wu H (2018). "A Case of Atrioventricular Block Potentially Associated with Right Coronary Artery Lesion and Ticagrelor Therapy Mediated by the Increasing Adenosine Plasma Concentration". Case Rep Vasc Med. 2018: 9385017. doi:10.1155/2018/9385017. PMC 5933017. PMID 29850368.
- ↑ Fu Md J, Bhatta L (2018). "Lyme carditis: Early occurrence and prolonged recovery". J Electrocardiol. 51 (3): 516–518. doi:10.1016/j.jelectrocard.2017.12.035. PMID 29275956.
- ↑ Tuohy S, Saliba W, Pai M, Tchou P (January 2018). "Catheter ablation as a treatment of atrioventricular block". Heart Rhythm. 15 (1): 90–96. doi:10.1016/j.hrthm.2017.08.015. PMID 28823599.
- ↑ Schernthaner C, Kraus J, Danmayr F, Hammerer M, Schneider J, Hoppe UC, Strohmer B (March 2016). "Short-term pacemaker dependency after transcatheter aortic valve implantation". Wien. Klin. Wochenschr. 128 (5–6): 198–203. doi:10.1007/s00508-015-0906-4. PMID 26745972.