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===Anatomy===
===Anatomy===
* The [[Conduction System|conduction system]] of [[heart]] consists of [[Specialize|specialized]] [[Cells (biology)|cells]] designed to [[Conductance|conduct]] [[electrical]] [[Impulse (psychology)|impulse]] faster than the surrounding [[myocardial]] [[Cells (biology)|cells]].
* The [[Conduction System|conduction system]] of [[heart]] consists of [[Specialize|specialized]] [[Cells (biology)|cells]] designed to [[Conductance|conduct]] [[electrical]] [[Impulse (psychology)|impulse]] faster than the surrounding [[myocardial]] [[Cells (biology)|cells]].
*[[Anatomical|Anatomically]], the [[Atrioventricular node|AV node]] is [[Division (biology)|divided]] into three regions as follows:
*[[Anatomical|Anatomically]], the [[Atrioventricular node|AV node]] is [[Division (biology)|divided]] into three [[Region of interest|regions]] as follows:
** Transitional cell zone: This is the region where the internodal atrial pathways merge with the compact AV node.
**'''[[Transitional cell]] zone''': This is the [[Region of interest|region]] where the [[Internodal segment|internodal]] [[atrial]] pathways merge with the [[Compact tissue|compact]] [[Atrioventricular node|AV node]].
** Compact AV node: This region is located at the apex of the [[triangle of Koch]], which is formed by the [[ostium]] of [[coronary sinus]], tricuspid annulus and the [[tendon of Todaro]].
**'''[[Compact tissue|Compact]] [[Atrioventricular node|AV node]]''': This [[Region of interest|region]] is [[Location parameter|located]] at the [[apex]] of the [[triangle of Koch]], which is formed by the [[ostium]] of [[coronary sinus]], [[tricuspid]] [[Annulus (mycology)|annulus]] and the [[tendon of Todaro]].
** Penetrating portion of the AV bundle: This region enters the [[tendon of Todaro]] and runs within the fibrous body of the [[interventricular septum|membranous interventricular septum]] and eventually divides at the crest of the [[interventricular septum|muscular interventricular septum]] into right and left branches.
**'''[[Penetration|Penetrating]] portion of the [[Atrioventricular|AV]] [[Bundle branch|bundle]]''': This [[Region of interest|region]] enters the [[tendon of Todaro]] and runs within the [[fibrous]] [[body]] of the [[interventricular septum|membranous interventricular septum]] and eventually [[Division (biology)|divides]] at the crest of the [[interventricular septum|muscular interventricular septum]] into right and left branches.
* The left bundle branch penetrates the membranous portion of the interventricular septum and divides into several smaller branches. Parts of the left bundle branch include a pre-divisional segment, anterior fascicle/hemibundle and posterior fascicle/hemibundle. Rarely a [[median]] fascicle is present in some hearts.
* The [[Left bundle branch block|left bundle branch]] [[Penetrance|penetrates]] the [[Membrane|membranous]] portion of the [[interventricular septum]] and [[Division (biology)|divides]] into several smaller branches. Parts of the [[Left bundle branch block|left bundle branch]] include a pre-[[Division (biology)|divisional]] [[Segment (linguistics)|segment]], [[anterior]] [[fascicle]]/hemibundle and [[posterior]] [[fascicle]]/hemibundle. Rarely a [[median]] [[fascicle]] is [[Presenting symptom|present]] in some [[Heart|hearts]].
** The anterior fascicle supplies the anterior [[papillary muscle]] and the [[Purkinje System|Purkinje network]] of the antero-lateral surface of the [[left ventricle]].
** The [[anterior]] [[fascicle]] supplies the [[anterior]] [[papillary muscle]] and the [[Purkinje System|Purkinje network]] of the [[Anterior|antero]]-[[lateral]] [[Surface anatomy|surface]] of the [[left ventricle]].
** The posterior fascicle supplies the posterior papillary muscle and the [[Purkinje System|Purkinje network]] of the postero-inferior surface of the [[left ventricle]].
** The [[posterior]] [[fascicle]] supplies the [[posterior]] [[papillary muscle]] and the [[Purkinje System|Purkinje network]] of the [[Posterior|postero]]-inferior [[Surface anatomy|surface]] of the [[left ventricle]].
** Left bundle branch receives its blood supply from [[left anterior descending artery]].
**[[Left bundle branch block|Left bundle branch]] receives its [[blood]] supply from [[left anterior descending artery]].
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===Pathophysiology of LBBB===
* Unlike [[right bundle branch block]] ([[RBBB]]), left bundle branch block completely modifies the way of depolarization of the conduction system of the heart.  In LBBB the activation of the [[interventricular septum]] is from right to left due to uninterrupted conduction in the RBB.
* Then the electrical impulse propagates inferiorly to the left resulting in delayed depolarization and activation of the [[left ventricle]] especially the left lateral wall.<ref name="pmid17385703">{{cite journal |author=Francia P, Balla C, Paneni F, Volpe M |title=Left bundle-branch block--pathophysiology, prognosis, and clinical management |journal=Clinical Cardiology |volume=30 |issue=3 |pages=110–5 |year=2007 |month=March |pmid=17385703 |doi=10.1002/clc.20034 |url=}}</ref>
* In LBBB the right to left  activation of the septum causes a small negative deflection ([[Q wave]]) in lead V<sub>1</sub> and a positive deflection ([[R wave]]) in lead V<sub>6</sub>. Right ventricle depolarizes earlier than the left ventricle giving an R wave in lead V<sub>1</sub> and an S wave in lead V<sub>6</sub>.  Subsequent delayed depolarization of the left ventricle results in an [[S wave]] in lead V<sub>1</sub> and another R wave in lead V<sub>6</sub>.


===Pathophysiology of Mobitz type II second degree AV block===
===Pathophysiology of Mobitz type II second degree AV block===
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:*[[Infranodal Wenkebach-type block|Infranodal]] [[Heart block|block]] and [[infra-Hisian block]] are [[Term logic|terms]] which [[Reference|refer]] to the [[anatomic]] [[Location parameter|location]] of the [[Heart block|block]], whereas
:*[[Infranodal Wenkebach-type block|Infranodal]] [[Heart block|block]] and [[infra-Hisian block]] are [[Term logic|terms]] which [[Reference|refer]] to the [[anatomic]] [[Location parameter|location]] of the [[Heart block|block]], whereas
:*[[Mobitz II]] [[Reference|refers]] to an [[electrocardiographic]] [[pattern]] [[Association (statistics)|associated]] with [[Heart block|block]] at these [[Leveling effect|levels]].<ref name="pmid29850368">{{cite journal |vauthors=Li X, Xue Y, Wu H |title=A Case of Atrioventricular Block Potentially Associated with Right Coronary Artery Lesion and Ticagrelor Therapy Mediated by the Increasing Adenosine Plasma Concentration |journal=Case Rep Vasc Med |volume=2018 |issue= |pages=9385017 |date=2018 |pmid=29850368 |pmc=5933017 |doi=10.1155/2018/9385017 |url=}}</ref>
:*[[Mobitz II]] [[Reference|refers]] to an [[electrocardiographic]] [[pattern]] [[Association (statistics)|associated]] with [[Heart block|block]] at these [[Leveling effect|levels]].<ref name="pmid29850368">{{cite journal |vauthors=Li X, Xue Y, Wu H |title=A Case of Atrioventricular Block Potentially Associated with Right Coronary Artery Lesion and Ticagrelor Therapy Mediated by the Increasing Adenosine Plasma Concentration |journal=Case Rep Vasc Med |volume=2018 |issue= |pages=9385017 |date=2018 |pmid=29850368 |pmc=5933017 |doi=10.1155/2018/9385017 |url=}}</ref>
===Pathophysiology of LBBB===
* Unlike [[right bundle branch block]] ([[RBBB]]), [[left bundle branch block]] completely modifies the way of [[depolarization]] of the [[Electrical conduction system of the heart|conduction system of the heart]].
*In [[Left bundle branch block|LBBB]] the [[Activation energy|activation]] of [[interventricular septum]] is from right to left due to uninterrupted [[Conductance|conduction]] in the [[Right bundle branch block|RBB]].
* Then the [[electrical]] [[Impulse (psychology)|impulse]] propagates [[inferiorly]] to the left [[Result|resulting]] in delayed [[depolarization]] and [[Activation energy|activation]] of the [[left ventricle]] especially the left [[lateral]] wall.<ref name="pmid17385703">{{cite journal |author=Francia P, Balla C, Paneni F, Volpe M |title=Left bundle-branch block--pathophysiology, prognosis, and clinical management |journal=Clinical Cardiology |volume=30 |issue=3 |pages=110–5 |year=2007 |month=March |pmid=17385703 |doi=10.1002/clc.20034 |url=}}</ref>
* In [[Left bundle branch block|LBBB]], the right to left [[Activation energy|activation]] of the [[septum]] [[causes]] a small negative deflection ([[Q wave]]) in [[lead]] [[V1-morph|V<sub>1</sub>]] and a [[positive]] deflection ([[R wave]]) in [[lead]] V<sub>6</sub>.
*The [[right ventricle]] [[Depolarization|depolarizes]] earlier than the [[left ventricle]] giving an [[R wave]] in [[lead]] [[V1-morph|V<sub>1</sub>]] and an [[S wave]] in [[lead]] V<sub>6</sub>.
*Subsequent delayed [[depolarization]] of the [[left ventricle]] [[Result|results]] in an [[S wave]] in [[lead]] [[V1-morph|V<sub>1</sub>]] and another [[R wave]] in [[lead]] V<sub>6</sub>.
===Pathophysiology of RBBB===
*[[Right bundle branch block]] occurs when the [[electrical]] [[Impulse (psychology)|impulse]] is not [[Conductance|conducted]] along the [[Right bundle branch block|right bundle branch]].
* As the [[Conduction System|conduction]] along the [[Left bundle branch block|left bundle branch]] remains unaffected, the [[electrical]] [[Impulse (psychology)|impulse]] [[Travel medicine|travels]] [[Normal|normally]] within the [[septum]] from left to right.
* However, the [[right ventricular]] [[contraction]] occurs [[Comparability|comparatively]] [[Slow|slowly]] giving the [[Characteristic impedance|characteristic]] 'M' [[pattern]] on the [[electrocardiogram]].
====Genetics====
*[[Familial]] [[Case-based reasoning|cases]] of [[right bundle branch block]] have been [[Observation|observed]] in 4 Lebanese [[Family|families]] and the [[Abnormality (behavior)|abnormality]] was mapped to [[chromosome 19]].
* There is a [[subset]] of [[patients]] with [[Brugada syndrome]] who have [[mutations]] in [[SCN5A]], the [[gene]] [[Encoding (memory)|encoding]] for the [[Voltage-gated sodium channel|voltage-gated cardiac sodium channel]].
====Associated Syndromes====
*[[Duchenne muscular dystrophy]]
*[[Myotonic dystrophy]]: Other [[EKG]] findings include:
**[[First-degree AV block]]
**[[Left anterior fascicular block]]
**[[Intraventricular conduction delay]]
**[[Arrhythmias]]
*[[Stokes-Adams attacks]]
*[[Kearns-Sayre Syndrome]]
*[[Brugada syndrome]]
====Pseudo Right Bundle Branch Block====
'''[[Brugada syndrome]]:'''
*[[Brugada syndrome]] is due to a [[channelopathy]] [[Mediated transport|mediated]] by the [[SCN5A]] [[gene]].
* The [[Right bundle branch block|RBBB]] [[pattern]] seen in [[patients]] of [[Brugada syndrome]] is not actually [[Right bundle branch block|RBBB]] but instead it is due to a [[repolarization]] [[Abnormality (behavior)|abnormality]]. Therefore, the [[Right bundle branch block|RBBB]] like [[pattern]] seen in [[Brugada syndrome]] is [[Reference|referred]] to as a 'pseudo [[right bundle branch block]]'.
*[[EKG]] findings include [[ST-segment elevation]] in [[Lead|leads]] [[V1-morph|V1]]-[[V3 loop|V3]].
*[[Cocaine]] [[Consumer/Survivor/Ex-Patient Movement|consumption]] and/or the [[Usage analysis|use]] of the [[antiarrhythmic]] [[propafenone]] may unmask the [[EKG]] findings seen in [[Brugada syndrome]].<ref name="pmid23613002">{{cite journal |author=Yildiz BS, Gungor H, Gul I, Bilgin M, Zoghi M, Akilli A |title=Is a drug-challenge test with propafenone adequate to exclude Brugada syndrome? |journal=Cardiovascular Journal of Africa |volume=24 |issue=2 |pages=e4–6 |year=2013 |pmid=23613002 |doi=10.5830/CVJA-2012-068 |url=}}</ref>


==Causes==
==Causes==
===Mobitz type II second degree AV block causes===
===Mobitz type II second degree AV block causes===
The potential etiologies of Mobitz type II second degree AV block include reversible (both pathologic and iatrogenic) and idiopathic causes that are similar to other degrees of AV block (table 1). Common potentially reversible causes include


Mobitz type II second degree AV block is rarely seen in patients without underlying heart disease. When identifiable, the reversible causes most commonly associated with Mobitz type II second degree AV block are myocardial infarction with ischemia of the AV node and medications that alter conduction through the AV node (eg, digoxin, beta blockers, calcium channel blockers). When no specific reversible cause is identified, the block is often felt to be related to idiopathic progressive cardiac conduction disease with myocardial fibrosis and/or sclerosis that affects the conduction system.
*[[Mobitz type II AV block|Mobitz type II]] [[second degree AV block]] is [[Rare|rarely]] seen in the [[patients]] without any [[Underlying representation|underlying]] [[heart disease]].
*The most common [[causes]] of [[Mobitz type II]] [[second degree AV block]] include:
** Reversible [[causes]] (both [[Pathological|pathologic]] and [[iatrogenic]])
**[[Idiopathic]] [[causes]] similar to other [[Degree (angle)|degrees]] of [[Atrioventricular block|AV block]] such as [[idiopathic]] progressive [[Cardiac conduction disorder|cardiac conduction disease]] with [[myocardial]] [[fibrosis]] and/or [[sclerosis]] [[Affect|affecting]] the [[Conduction system disease|conduction system]].
 
* Details of all the possible [[etiologies]] are given in the table below:


{| class="wikitable"
{| class="wikitable"
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* [[sex linkage|X-linked inherited  conditions]]
* [[sex linkage|X-linked inherited  conditions]]
{{col-end}}
{{col-end}}
*'''For causes of [[Left bundle branch block]], click [[Left bundle branch block causes|here]].'''
*'''For causes of [[Right bundle branch block]], click [[Right bundle branch block causes|here]].'''


==Epidemiology and Demographics==
==Epidemiology and Demographics==

Latest revision as of 20:59, 19 August 2020

Infra-Hisian Block Microchapters

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

Treatment

Prevention

Differentiating Infra-Hisian Block from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Sara Mohsin, M.D.[2]

Overview

Infra-Hisian block is defined as an impaired conduction in the electrical system of the heart that occurs below the atrioventricular node.

Historical Perspective

Classification

Classification of Infra-Hisian Block
Types of Infra-Hisian Block Sub-type
Type 2 second degree heart block (Mobitz II) _
Left bundle branch block Left anterior fascicular block
Left posterior fascicular block
Right bundle branch block _

Pathophysiology

Normal Cardiac Conduction

  1. The normal cardiac conduction proceeds in a way so as to allow time for the atrium to relax during atrial diastole.
  2. The electrical impulse generated in the SA node travels through the internodal pathways towards the AV node.
  3. The conduction through the AV node is slowed down as it travels through it. This decrease in velocity of conduction allows time for the atrium to contract ahead of the ventricle so that the blood from the atria can fill up the ventricles through the atrioventricular valves.
  4. As the impulse flows through the compact AV node, it rapidly conducts through the ventricular myocardial cells. Once the depolarization is complete, the ventricle relaxes during diastole in preparation for the next impulse.

Anatomy

Conduction system of the heart
Structure of the heart's conduction system

Pathophysiology of Mobitz type II second degree AV block

Pathophysiology of LBBB

Pathophysiology of RBBB

Genetics

Associated Syndromes

Pseudo Right Bundle Branch Block

Brugada syndrome:

Causes

Mobitz type II second degree AV block causes

  • Details of all the possible etiologies are given in the table below:
Major reversible causes of atrioventricular (AV) block
Physiologic and pathophysiologic
Increased vagal tone
  • Also known as hypervagotonia
Ischemic heart disease
Progressive cardiac conduction system disease Associated with:
Infections
Cardiomyopathy Infiltrative processes such as:

Other non-ischemic cardiomyopathies include:

Congenital AV block
Other reversible causes
Iatrogenic
Drugs (altering conduction through AV node)
Cardiac surgery
Catheter ablation of arrhythmias
Alcohol septal ablation for hypertrophic cardiomyopathy
Transcatheter closure of ventricular septal defect
Post-transcatheter aortic valve implantation

Life Threatening Causes

Life-threatening conditions can result in death or permanent disability within 24 hours if left untreated.[7]

Common Causes

Causes by Organ System

Cardiovascular Acute myocardial infarction, acute rheumatic fever, ASD, dilated cardiomyopathy, Ebstein's anomaly, hypersensitive carotid sinus syndrome, hypertension, hypertrophic cardiomyopathy, Lev's disease, myocardial bridging, myocarditis, normal variants, post aortic valve replacement, post catheter ablation for arrhythmias, post closure of a ventricular septal defect, post mitral valve replacement, tetralogy of Fallot, endocardial cushion defect, transposition of the great vessels, valvular heart disease, VSD
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug Side Effect Amiodarone, beta-blockers, digitalis, calcium channel blockers, cholinesterase inhibitors, disopyramide, dofetilide, dolasetron, donepezil, eslicarbazepine acetate, fesoterodine, fingolimod, flecainide, ibutilide, lacosamide, magnesium, paliperidone, pramipexole, procainamide, propafenone, propoxyphene, quinidine, sotalol, terodiline
Ear Nose Throat No underlying causes
Endocrine Hyperthyroidism, myxedema, thyrotoxic periodic paralysis
Environmental Hypothermia
Gastroenterologic Hemochromatosis
Genetic Emery-Dreifuss muscular dystrophy, Fabry disease, glycogenosis type 2b, hereditary neuromuscular disease, Kearns-Sayre syndrome
Hematologic Multiple myeloma Lymphoma[11]
Iatrogenic Post aortic valve replacement, post catheter ablation for arrhythmias, post closure of a ventricular septal defect, post mitral valve replacement
Infectious Disease Acute rheumatic fever, Chagas disease, diphtheria, Lyme disease, myocarditis, neonatal lupus erythematosus, protozoal infection, sarcoidosis, SLE, tuberculosis
Musculoskeletal / Ortho Ankylosing spondylitis, hereditary neuromuscular disease, Kearns-Sayre syndrome, mitochondrial genome inherited conditions, muscular dystrophy
Neurologic Enhanced vagal tone
Nutritional / Metabolic Fabry disease, glycogenosis type 2b
Obstetric/Gynecologic No underlying causes
Oncologic Multiple myeloma
Opthalmologic No underlying causes
Overdose / Toxicity No underlying causes
Psychiatric No underlying causes
Pulmonary Sarcoidosis
Renal / Electrolyte Hyperkalemia, hypokalemia
Rheum / Immune / Allergy Ankylosing spondylitis, dermatomyositis, rheumatoid arthritis, scleroderma, SLE
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Dental No underlying causes
Miscellaneous Amyloidosis, degenerative diseases

Causes in Alphabetical Order

Epidemiology and Demographics

Prevalence

Gender

Risk Factors

Natural History, Complications and Prognosis

Natural History

Complications

Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Patients with second degree AV block should be checked for the following laboratory tests:[27]

Electrocardiogram


Shown below is an electrocardiogram of a 12 lead EKG with a 2:1 AV block.

Copyleft image obtained, courtesy of ECGpedia, http://en.ecgpedia.org/wiki/Main_Page


Shown below is an electrocardiogram of a type II second degree AV block (Mobitz type II).

Copyleft image obtained, courtesy of ECGpedia, http://en.ecgpedia.org/wiki/Main_Page


Treatment

Medical therapy for Mobitz II

Contraindicated medications

Second degree AV block(except in patients with a functioning artificial pacemaker)[30][31] is considered an absolute contraindication to the use of the following medications:

Surgery for Mobitz II

Definitive treatment-Pacemaker insertion

Prevention

Primary Prevention

Differentiating Infra-Hisian Block from other Diseases


Arrhythmia Rhythm Rate P wave PR Interval QRS Complex Response to Maneuvers Epidemiology Co-existing Conditions
Atrioventricular block[36] First degree [37][38]
  • Regular



Second degree[12][39] QRS is normal but dropped as the following:
Third degree[40][41]
  • Regular
Atrial Fibrillation (AFib)[42][43]
  • Absent
Atrial Flutter[44]
Atrioventricular nodal reentry tachycardia (AVNRT)[45][46][47][48]
  • Regular
Multifocal Atrial Tachycardia[49][50]
Paroxysmal Supraventricular Tachycardia
  • Regular
  • 150 and 240 bpm
  • Absent
  • Hidden in QRS
  • Absent
Premature Atrial Contractrions (PAC)[51][52]
  • Upright
  • Usually narrow (< 0.12 s)
Wolff-Parkinson-White Syndrome[53][54]
  • Regular
Ventricular Fibrillation (VF)[55][56][57]
  • Absent
  • Absent
Ventricular Tachycardia[58][59]
  • Regular
  • > 100 bpm (150-200 bpm common)
  • Absent

References

  1. Upshaw CB, Silverman ME (2000). "John Hay: discoverer of type II atrioventricular block". Clin Cardiol. 23 (11): 869–71. doi:10.1002/clc.4960231118. PMC 6655013 Check |pmc= value (help). PMID 11097138.
  2. Puech P, Wainwright RJ (1983). "Clinical electrophysiology of atrioventricular block". Cardiol Clin. 1 (2): 209–24. PMID 6544636.
  3. 3.0 3.1 3.2 3.3 Wogan JM, Lowenstein SR, Gordon GS (1993). "Second-degree atrioventricular block: Mobitz type II". J Emerg Med. 11 (1): 47–54. doi:10.1016/0736-4679(93)90009-v. PMID 8445186.
  4. 4.0 4.1 4.2 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.
  5. Francia P, Balla C, Paneni F, Volpe M (2007). "Left bundle-branch block--pathophysiology, prognosis, and clinical management". Clinical Cardiology. 30 (3): 110–5. doi:10.1002/clc.20034. PMID 17385703. Unknown parameter |month= ignored (help)
  6. Yildiz BS, Gungor H, Gul I, Bilgin M, Zoghi M, Akilli A (2013). "Is a drug-challenge test with propafenone adequate to exclude Brugada syndrome?". Cardiovascular Journal of Africa. 24 (2): e4–6. doi:10.5830/CVJA-2012-068. PMID 23613002.
  7. 7.0 7.1 7.2 7.3 Mangi MA, Jones WM, Napier L. PMID 29493981. Missing or empty |title= (help)
  8. Misumida N, Ogunbayo GO, Kim SM, Abdel-Latif A, Ziada KM, Elayi CS (November 2018). "Frequency and Significance of High-Degree Atrioventricular Block and Sinoatrial Node Dysfunction in Patients With Non-ST-Elevation Myocardial Infarction". Am. J. Cardiol. 122 (10): 1598–1603. doi:10.1016/j.amjcard.2018.08.001. PMID 30227965.
  9. 9.0 9.1 9.2 Barold SS, Herweg B (December 2012). "Second-degree atrioventricular block revisited". Herzschrittmacherther Elektrophysiol. 23 (4): 296–304. doi:10.1007/s00399-012-0240-8. PMID 23224264.
  10. Kamatani T, Akizuki A, Kondo S, Shirota T (Fall 2016). "Second-Degree Atrioventricular Block Occurring After Tooth Extraction". Anesth Prog. 63 (3): 156–9. doi:10.2344/15-00042.1. PMC 5011958. PMID 27585419.
  11. Menicagli F, Lanza A, Sbrocca F, Baldi A, Spugnini EP (2016). "A case of advanced second-degree atrioventricular block in a ferret secondary to lymphoma". Open Vet J. 6 (1): 68–70. doi:10.4314/ovj.v6i1.10. PMC 4833871. PMID 27200273.
  12. 12.0 12.1 Zehender M, Meinertz T, Keul J, Just H (1990). "ECG variants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance". Am Heart J. 119 (6): 1378–91. doi:10.1016/s0002-8703(05)80189-9. PMID 2191578.
  13. 13.0 13.1 13.2 Meimoun P, Zeghdi R, D'Attelis N, Berrebi A, Braunberger E, Deloche A; et al. (2002). "Frequency, predictors, and consequences of atrioventricular block after mitral valve repair". Am J Cardiol. 89 (9): 1062–6. doi:10.1016/s0002-9149(02)02276-2. PMID 11988196.
  14. Meimoun P, Zeghdi R, D'Attelis N, Berrebi A, Braunberger E, Deloche A; et al. (2002). "Frequency, predictors, and consequences of atrioventricular block after mitral valve repair". Am J Cardiol. 89 (9): 1062–6. doi:10.1016/s0002-9149(02)02276-2. PMID 11988196.
  15. Kerola T, Eranti A, Aro AL, Haukilahti MA, Holkeri A, Junttila MJ, Kenttä TV, Rissanen H, Vittinghoff E, Knekt P, Heliövaara M, Huikuri HV, Marcus GM (May 2019). "Risk Factors Associated With Atrioventricular Block". JAMA Netw Open. 2 (5): e194176. doi:10.1001/jamanetworkopen.2019.4176. PMC 6632153 Check |pmc= value (help). PMID 31125096.
  16. Schoeller R, Andresen D, Büttner P, Oezcelik K, Vey G, Schröder R (March 1993). "First- or second-degree atrioventricular block as a risk factor in idiopathic dilated cardiomyopathy". Am. J. Cardiol. 71 (8): 720–6. doi:10.1016/0002-9149(93)91017-c. PMID 8447272.
  17. Rodstein M, Wolloch L, Iuster Z (1979). "The natural history intraventricular conduction disturbances in the aged: an analysis of the developing second and third degree heart block with clinical pathological correlations". Am. J. Med. Sci. 277 (2): 179–88. doi:10.1097/00000441-197903000-00006. PMID 463945.
  18. 18.0 18.1 Bexton RS, Camm AJ (March 1984). "Second degree atrioventricular block". Eur. Heart J. 5 Suppl A: 111–4. doi:10.1093/eurheartj/5.suppl_a.111. PMID 6373268.
  19. Thiruganasambandamoorthy V, Hess EP, Turko E, Tran ML, Wells GA, Stiell IG (July 2012). "Defining abnormal electrocardiography in adult emergency department syncope patients: the Ottawa Electrocardiographic Criteria". CJEM. 14 (4): 248–58. PMID 22813399.
  20. Barold SS, Van Heuverswyn FE, Timmers L, Stroobandt RX (August 2014). "Mobitz type II second-degree atrioventricular block during dobutamine stress echocardiography. True or false?". Echocardiography. 31 (7): 799–801. doi:10.1111/echo.12577. PMID 25080840.
  21. 21.0 21.1 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.
  22. 22.0 22.1 Kashou AH, Goyal A, Nguyen T, Chhabra L. PMID 29083636. Missing or empty |title= (help)
  23. Zeppilli P, Fenici R, Sassara M, Pirrami MM, Caselli G (September 1980). "Wenckebach second-degree A-V block in top-ranking athletes: an old problem revisited". Am. Heart J. 100 (3): 281–94. doi:10.1016/0002-8703(80)90140-4. PMID 7405798.
  24. Rosen KM, Dhingra RC, Loeb HS, Rahimtoola SH (1973). "Chronic heart block in adults. Clinical and electrophysiological observations". Arch Intern Med. 131 (5): 663–72. PMID 4701376.
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