Third degree AV block medical therapy: Difference between revisions

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__NOTOC__
__NOTOC__
{{Third degree AV block}}
{{Third degree AV block}}
{{CMG}}; {{AE}} {{CZ}} {{RT}} {{Soroush}} [[User:Qasim Khurshid|Qasim Khurshid, M.B.B.S. [5]]]
{{CMG}}; {{AE}} {{Sara.Zand}} {{CZ}} {{RT}} {{Soroush}} [[User:Qasim Khurshid|Qasim Khurshid, M.B.B.S. [5]]]


== Overview ==
== Overview ==
The management of third-degree heart block varies widely from observation to the placement of a pacemaker. The new onset of third-degree heart block is a medical emergency.  
The management of third-degree [[AV block]] depends on the severity of signs, [[symptoms]], and the underlying cause. In symptomatic [[patients]] and with [[hemodynamic]] distress, [[pharmacological]] therapy should be initiated immediately to increase [[heart rate]] and [[cardiac output]]. Most of the [[patients]] who do not respond to [[pharmacologic]] therapy require a [[temporary pacemaker]]. After stabilizing the [[patients]], assessment and treatment of potentially [[reversible ]] causes should be done. Some [[patients]] without reversible cause or unidentified [[etiology]] require a [[permanent pacemaker]].


==Medical Therapy==
==Medical Therapy==
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{|
{|
! colspan="2" style="background: PapayaWhip;" align="center" + |The above table adopted from 2018 AHA/ACC/HRS Guideline
! colspan="2" style="background: PapayaWhip;" align="center" + |The above table adopted from 2018 AHA/ACC/HRS Guideline<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>
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| Colspan="2" style="text-align:center; background:LemonChiffon"|[[ACC AHA guidelines classification scheme#Classification of Recommendations|Class III]]
| Colspan="2" style="text-align:center; background:LemonChiffon"|[[ACC AHA guidelines classification scheme#Classification of Recommendations|Class III]]
|-
|-
| Bgcolor="LemonChiffon"|<nowiki>"</nowiki>'''1''' [[Dialysis]] is not benefit in [[patients]] presented with [[bradycardia]] associated [[digoxin]] toxicity'' ([[ACC AHA guidelines classification scheme#Level of Evidence|Level of Evidence C]])<nowiki>"</nowiki>''
| Bgcolor="LemonChiffon"|<nowiki>"</nowiki>'''2''' [[Dialysis]] is not benefit in [[patients]] presented with [[bradycardia]] associated [[digoxin]] toxicity'' ([[ACC AHA guidelines classification scheme#Level of Evidence|Level of Evidence C]])<nowiki>"</nowiki>''
|}
|}


 
* [[Digoxin]]-specific antibody ([[Fab]]) is a monovalent [[immunoglobulin]] that rapidly binds to [[intravascular]] [[digoxin]].<ref name="pmid25089630">{{cite journal |vauthors=Chan BS, Buckley NA |title=Digoxin-specific antibody fragments in the treatment of digoxin toxicity |journal=Clin Toxicol (Phila) |volume=52 |issue=8 |pages=824–36 |date=2014 |pmid=25089630 |doi=10.3109/15563650.2014.943907 |url=}}</ref>
* Each vial of 40 mg of [[digoxin]] Fab binds  0.5 mg of [[digoxin]] and dosage is dependent on the estimated amount of ingested [[digoxin]].<ref name="pmid25089630">{{cite journal |vauthors=Chan BS, Buckley NA |title=Digoxin-specific antibody fragments in the treatment of digoxin toxicity |journal=Clin Toxicol (Phila) |volume=52 |issue=8 |pages=824–36 |date=2014 |pmid=25089630 |doi=10.3109/15563650.2014.943907 |url=}}</ref>
* [[Hyperkalemia]] or [[arrhythmias]] in the setting of [[digoxin]] [[serum]] levels of >2 mcg/L  put  the [[patients]] at increased risk of [[death]].
* [[Signs]] and [[symptoms]] of [[toxicity]] can present at lower [[serum]] levels leading to [[sinus node dysfunction]] or [[atrioventricular block]].




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<br>
<br>
{|
{|
! colspan="2" style="background: PapayaWhip;" align="center" + |The above table adopted from 2018 AHA/ACC/HRS Guideline
! colspan="2" style="background: PapayaWhip;" align="center" + |The above table adopted from 2018 AHA/ACC/HRS Guideline<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>
|-  
|-  
|}
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==Notes==
==Notes==
* In the presence of new [[atrioventricular block]], evaluation about reversible causes is recommended.
* In the presence of new [[atrioventricular block]], evaluation about reversible causes is recommended.
* [[Complete heart block]] is the most common manifestation of [[lyme]] [[carditis]] and reversible with appropriate [[antibiotic]] therapy.<ref name="ForresterMead2014">{{cite journal|last1=Forrester|first1=J. D.|last2=Mead|first2=P.|title=Third-Degree Heart Block Associated With Lyme Carditis: Review of Published Cases|journal=Clinical Infectious Diseases|volume=59|issue=7|year=2014|pages=996–1000|issn=1058-4838|doi=10.1093/cid/ciu411}}</ref>
* [[Complete heart block]] is the most common manifestation of [[lyme]] [[carditis]], commonly is reversible with appropriate [[antibiotic]] therapy.<ref name="ForresterMead2014">{{cite journal|last1=Forrester|first1=J. D.|last2=Mead|first2=P.|title=Third-Degree Heart Block Associated With Lyme Carditis: Review of Published Cases|journal=Clinical Infectious Diseases|volume=59|issue=7|year=2014|pages=996–1000|issn=1058-4838|doi=10.1093/cid/ciu411}}</ref>
* [[Atrioventricular block]] due to  [[digoxin toxicity]] may be reversible after drug washout or using a neutralized antibody.<ref name="AntmanWenger1990">{{cite journal|last1=Antman|first1=E M|last2=Wenger|first2=T L|last3=Butler|first3=V P|last4=Haber|first4=E|last5=Smith|first5=T W|title=Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments. Final report of a multicenter study.|journal=Circulation|volume=81|issue=6|year=1990|pages=1744–1752|issn=0009-7322|doi=10.1161/01.CIR.81.6.1744}}</ref>
* [[Atrioventricular block]] due to  [[digoxin toxicity]] may be reversible after drug washout or using a neutralized antibody.<ref name="AntmanWenger1990">{{cite journal|last1=Antman|first1=E M|last2=Wenger|first2=T L|last3=Butler|first3=V P|last4=Haber|first4=E|last5=Smith|first5=T W|title=Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments. Final report of a multicenter study.|journal=Circulation|volume=81|issue=6|year=1990|pages=1744–1752|issn=0009-7322|doi=10.1161/01.CIR.81.6.1744}}</ref>
* Commonly, [[atrioventricular block]] due to [[overdose]] of  [[antiarrhythmic]] drugs, [[calcium channel blocker]] or [[betablocker]] is reversible. <ref name="KennebäckTabrizi2007">{{cite journal|last1=Kennebäck|first1=Göran|last2=Tabrizi|first2=Fariborz|last3=Lindell|first3=Peter|last4=Nordlander|first4=Rolf|title=High-degree atrioventricular block during anti-arrhythmic drug treatment: use of a pacemaker with a bradycardia-detection algorithm to study the time course after drug withdrawal|journal=EP Europace|volume=9|issue=3|year=2007|pages=186–191|issn=1532-2092|doi=10.1093/europace/eul185}}</ref>
* Commonly, [[atrioventricular block]] due to [[overdose]] of  [[antiarrhythmic]] drugs, [[calcium channel blocker]] or [[betablocker]] are reversible. <ref name="KennebäckTabrizi2007">{{cite journal|last1=Kennebäck|first1=Göran|last2=Tabrizi|first2=Fariborz|last3=Lindell|first3=Peter|last4=Nordlander|first4=Rolf|title=High-degree atrioventricular block during anti-arrhythmic drug treatment: use of a pacemaker with a bradycardia-detection algorithm to study the time course after drug withdrawal|journal=EP Europace|volume=9|issue=3|year=2007|pages=186–191|issn=1532-2092|doi=10.1093/europace/eul185}}</ref>
* [[Atrioventricular bliock]] in the setting of the therapeutic dose of [[calcium channel blocker]] or [[betablocker]] was irreversible and insertion of [[permanent pacemaker]] was needed in some cases.  
* [[Atrioventricular block]] in the setting of therapeutic dose of [[calcium channel blocker]] or [[betablocker]], [[antiarrhythmic]] drugs class 1,3 in [[patients]] with [[heart failure]] or [[ischemic heart disease]] may be irreversible even after cessation of [[drugs]] and insertion of [[permanent pacemaker]] was needed in some cases.<ref name="OsmonovErdinler2012">{{cite journal|last1=Osmonov|first1=Damirbek|last2=Erdinler|first2=Izzet|last3=Ozcan|first3=Kazim Serhan|last4=Altay|first4=Servet|last5=Turkkan|first5=Ceyhan|last6=Yildirim|first6=Ersin|last7=Hasdemir|first7=Hakan|last8=Alper|first8=Ahmet Taha|last9=Cakmak|first9=Nazmiye|last10=Satilmis|first10=Seckin|last11=Gurkan|first11=Kadir|title=Management of Patients with Drug-Induced Atrioventricular Block|journal=Pacing and Clinical Electrophysiology|volume=35|issue=7|year=2012|pages=804–810|issn=01478389|doi=10.1111/j.1540-8159.2012.03410.x}}</ref>
* Before making decision for [[ placement of permanent pacemakeker]] in [[atrioventricular block]] in the setting of [[cardiac sarcoidosis]] or [[hypothyroidism]] medical therapy is appropriate.<ref name="pmid21427276">{{cite journal |vauthors=Kandolin R, Lehtonen J, Kupari M |title=Cardiac sarcoidosis and giant cell myocarditis as causes of atrioventricular block in young and middle-aged adults |journal=Circ Arrhythm Electrophysiol |volume=4 |issue=3 |pages=303–9 |date=June 2011 |pmid=21427276 |doi=10.1161/CIRCEP.110.959254 |url=}}</ref><ref name="OzcanOsmonov2012">{{cite journal|last1=Ozcan|first1=Kazim Serhan|last2=Osmonov|first2=Damirbek|last3=Erdinler|first3=Izzet|last4=Altay|first4=Servet|last5=Yildirim|first5=Ersin|last6=Turkkan|first6=Ceyhan|last7=Hasdemir|first7=Hakan|last8=Cakmak|first8=Nazmiye|last9=Alper|first9=Ahmet Taha|last10=Satilmis|first10=Seckin|last11=Gurkan|first11=Kadir|title=Atrioventricular block in patients with thyroid dysfunction: Prognosis after treatment with hormone supplementation or antithyroid medication|journal=Journal of Cardiology|volume=60|issue=4|year=2012|pages=327–332|issn=09145087|doi=10.1016/j.jjcc.2012.05.012}}</ref>
* Before making decision for [[ placement of permanent pacemakeker]] in [[atrioventricular block]] in the setting of [[cardiac sarcoidosis]] or [[hypothyroidism]], medical therapy including [[hormone]] therapy for [[hypothyroidism]] and [[corticosteroid]] therapy for [[cardiac ]] [[sarcoidosis]] is appropriate.<ref name="pmid21427276">{{cite journal |vauthors=Kandolin R, Lehtonen J, Kupari M |title=Cardiac sarcoidosis and giant cell myocarditis as causes of atrioventricular block in young and middle-aged adults |journal=Circ Arrhythm Electrophysiol |volume=4 |issue=3 |pages=303–9 |date=June 2011 |pmid=21427276 |doi=10.1161/CIRCEP.110.959254 |url=}}</ref><ref name="OzcanOsmonov2012">{{cite journal|last1=Ozcan|first1=Kazim Serhan|last2=Osmonov|first2=Damirbek|last3=Erdinler|first3=Izzet|last4=Altay|first4=Servet|last5=Yildirim|first5=Ersin|last6=Turkkan|first6=Ceyhan|last7=Hasdemir|first7=Hakan|last8=Cakmak|first8=Nazmiye|last9=Alper|first9=Ahmet Taha|last10=Satilmis|first10=Seckin|last11=Gurkan|first11=Kadir|title=Atrioventricular block in patients with thyroid dysfunction: Prognosis after treatment with hormone supplementation or antithyroid medication|journal=Journal of Cardiology|volume=60|issue=4|year=2012|pages=327–332|issn=09145087|doi=10.1016/j.jjcc.2012.05.012}}</ref>






{| style="cellpadding=0; cellspacing= 0; width: 600px;"
|-
| style="padding: 0 5px; font-size: 100%; background: #4682B4; color: #FFFFFF;" align=center |'''Recommendations for acute medical therapy for bradycardia associated atrioventricular block'''
|-
|style="font-size: 100; padding: 0 5px; background: #B8B8B8" align=left |''' Medical therapy  ([[ACC AHA guidelines classification scheme|Class IIa, Level of Evidence C]]):'''
|-
|style="padding: 0 5px; font-size: 100%; background: #F5F5F5; width: 70%" align=left|
❑ [[ Atropine]] is reasonable for  [[patients]] with  [[symptomatic]] [[bradycardia ]] associated second-degree or [[third degree atrioventricular block]] at the [[atrioventricular]] nodal level <br>
|-
|style="font-size: 100; padding: 0 5px; background: #B8B8B8" align=left |''' Medical therapy  ([[ACC AHA guidelines classification scheme|Class IIb, Level of Evidence B]]):'''
|-
|style="padding: 0 5px; font-size: 100%; background: #F5F5F5; width: 70%" align=left|
❑ [[Beta adrenergic agonist]] such as [[isoproterenol]], [[dopamine]], [[dobutamine]] is recommended for symptomatic  [[bradycardia]] associated [[second degree]] or third degree [[atrioventricular block]] with low likehood of [[ischemia]]<br>
|-
|style="font-size: 100; padding: 0 5px; background: #B8B8B8" align=left |''' Medical therapy  ([[ACC AHA guidelines classification scheme|Class IIb, Level of Evidence C]]):'''
|-
|style="padding: 0 5px; font-size: 100%; background: #F5F5F5; width: 70%" align=left|
❑ [[Aminophylline]] is recommended for [[symptomatic]] [[bradycardia]] associated second or third degree [[atrioventricular block]] in the setting of [[acute]] [[inferior MI]]<br>
|}


==Comment==
*''' [[Atropine]]''' is a [[parasympatholytic]] [[drug]] that increase [[atrioventricular]] nodal conduction and [[automaticity]] when [[atrioventricular block]] is  at the atrioventricular nodal level or  [[bradycardia]] is related to excess [[vagal tone]].
* Dosage is 0.5- to 1.0-mg IV, may be repeated.
* [[Atropine]] may enhance [[atrioventricular]] conduction in the setting of [[inferior MI]].
* For [[atrioventricular block]] at the level of [[His bundle]] or [[His-Purkinje]], [[atropine]] may worsen [[atrioventricular conduction]] or compromise [[hemodynamic]].
* Common adver effects of [[atropine]] include [[dry mouth]], [[blurred vision]], [[anhidrosis]], [[urinary retention]], and [[delirium]] , increased [[heart rate]] in the setting of [[MI]].


*'''[[Beta-adrenergic agonists]]''' such as [[isoproterenol]], [[dopamine]], [[dobutamine]], and [[epinephrine]] may have direct effect to increase [[ atrioventricular]] nodal and, to a lesser degree, [[His-Purkinje]] conduction.
* The efficacy of [[dopamine]] was equal to [[transcutaneous pacing]] in 1 small randomized trial of [[patients]] with unstable [[bradycardia]] unresponsive to [[atropine]].<ref name="pmid5557475">{{cite journal |vauthors=Hatle L, Rokseth R |title=Conservative treatment of AV block in acute myocardial infarction. Results in 105 consecutive patients |journal=Br Heart J |volume=33 |issue=4 |pages=595–600 |date=July 1971 |pmid=5557475 |pmc=487219 |doi=10.1136/hrt.33.4.595 |url=}}</ref>


 
*Common adverse effects of [[beta-adrenergic agonists]] may include [[ventricular arrhythmias]] , induction of [[coronary ischemia]], particularly in the setting of acute [[MI]].
 
*[[Isoproterenol]] because of the [[vasodilatory]] effects may exacerbate [[hypotension]].
 
*'''[[Aminophylline]]''' is a nonselective [[adenosine]] receptor antagonist and [[phosphodiesterase inhibitor]].
 
* Safety and efficacy of [[aminophylline]] for reversing  [[bradycardia]] associated [[atrioventricular]] block in the setting of excess [[adnosine]] production in [[inferior MI]] was shown. <ref name="pmid17933452">{{cite journal |vauthors=Morrison LJ, Long J, Vermeulen M, Schwartz B, Sawadsky B, Frank J, Cameron B, Burgess R, Shield J, Bagley P, Mausz V, Brewer JE, Dorian P |title=A randomized controlled feasibility trial comparing safety and effectiveness of prehospital pacing versus conventional treatment: 'PrePACE' |journal=Resuscitation |volume=76 |issue=3 |pages=341–9 |date=March 2008 |pmid=17933452 |pmc=7126680 |doi=10.1016/j.resuscitation.2007.08.008 |url=}}</ref>
 
* There was no benefit for [[aminophylline]] in [[resuscitation]] for [[out-of-hospital]] brady-[[asystolic]] [[cardiac arrest]] based on a large randomized trial and a systematic review.<ref name="pmid26593309">{{cite journal |vauthors=Hurley KF, Magee K, Green R |title=Aminophylline for bradyasystolic cardiac arrest in adults |journal=Cochrane Database Syst Rev |volume= |issue=11 |pages=CD006781 |date=November 2015 |pmid=26593309 |doi=10.1002/14651858.CD006781.pub3 |url=}}</ref>
 
 
 
 
 
 
 
The management of third-degree [[AV block]] depends on the severity of signs, symptoms, and the underlying cause. In symptomatic patients and with hemodynamic distress, pharmacological therapy should be initiated immediately to increase heart rate and [[cardiac output]]. Most of the patients who do not respond to pharmacologic therapy require a [[temporary pacemaker]]. After stabilizing the patients, assessment and treatment of potentially reversible causes should be done. Some patients without reversible cause or unidentified etiology require a permanent pacemaker<ref name=":0">Kusumoto FM, Schoenfeld MH, Barrett C, et al. 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 [published correction appears in J Am Coll Cardiol. 2019 Aug 20;74(7):1016-1018]. ''J Am Coll Cardiol''. 2019;74(7):e51‐e156. doi:10.1016/j.jacc.2018.10.044</ref>. A new third degree [[Atrioventricular block|AV block]] is an emergency. Management is slightly different between unstable and stable patients. 
 
===Management of Unstable Patients===
The most critical factor in determining the management of [[third-degree AV block]] patients is hemodynamic stability. Patients of third-degree AV block with hemodynamic instability should be urgently treated with [[Atropine (Injection)|atropine]] and temporary cardiac pacemaker.
 
*[[Atropine]] should be given urgently with an initial dose of 0.5 mg IV and can be repeated every three to five minutes with a total dose of 3 mg.  Atropine is most effective if the AV block is due to abnormal conduction through the [[AV node]]. Atropine is not useful in wide complex [[bradyarrhythmias]] (block below the AV node). It is also not helpful in a denervated heart, like in patients who have undergone a [[Cardiac transplantation|cardiac transplant]] procedure. Treatment with atropine should be followed by [[transcutaneous pacing]] or a chronotropic agent.
* Hemodynamically unstable patients should be immediately provided with a temporary cardiac pacemaker. [[Transcutaneous pacing]] can be initiated more rapidly as compared to a [[transvenous pacemaker]], which requires more expertise. However, a transvenous pacemaker is more durable and comfortable for the patient. Transcutaneous pacing should be used temporarily until temporary transvenous pacing can be provided.
*In patients presenting with [[hypotension]] and third-degree AV block, [[dopamine]] should be given as IV infusion, starting at a dose of 3mcg/kg/min and can be titrated up to 20 mcg/kg/min for stabilization of blood pressure and heart rate.
*In patients presenting with heart failure symptoms and left ventricular dysfunction associated with third-degree  AV block,  [[Dobutamine dosage and administration|dobutamine]] is given via IV infusion, with a starting dose of 5 mcg/kg/minute and can be titrated up to 40 mcg/kg/minute if required.
 
After stabilizing the hemodynamically unstable patients, the approach to further management is the same as for initially stable patients.
 
====Management of Stable Patients ====
Hemodynamically stable patients of third-degree heart block do not require urgent treatment with atropine and pacemaker. However, many ventricular escape rhythms have the potential to become unstable, so patients should be monitored on the telemetry floor or ICU.
 
While monitoring patients, management should be as fellows.
 
* Reversible causes of third-degree heart block should be evaluated before [[implantation]] of the permanent pacemaker. Such causes include [[myocardial ischemia]], [[hyperkalemia]], increased vagal tone, and [[medications]] that depress the conduction through the AV node.
 
* Patients of third-degree AV block due to [[acute myocardial infarction]] can be managed with revascularization and temporary cardiac pacing. Most of the patients improve after [[Revascularization with CABG or PCI had no Difference on Outcomes of Death, non-fatal MI, or CVA for Diabetics with Multi-Vessel Coronary Disease: Results of the CARDia Trial|revascularization]] and do not require a permanent pacemaker.
 
* Many medications that are used to treat cardiovascular conditions such as [[Antihypertensive medication|antihypertensive]], antianginal, and [[antiarrhythmic drugs]] cause AV block that resolves after the removal of the offending agents. These medications can induce or aggravate a third-degree heart block. The most common drugs include [[beta-blockers]], [[calcium channel blockers]], [[antiarrhythmics]], and [[digoxin]]. Patients of third-degree heart block caused by drug toxicities should be managed in the same fashion(e.g., atropine and pacemaker) as caused by other etiologies. But these patients should also get treatment for respective drug toxicity. Most of the time, a permanent pacemaker is not required in these patients.
 
* Patients with [[third-degree (complete) AV block]] because of [[hyperkalemia]] should receive therapy to reduce serum potassium levels. If third-degree  AV block subsequently resolves, a permanent pacemaker is not usually needed.
* Third-degree (complete) AV block caused by [[Lyme carditis]] typically improves to lesser degrees of AV block within one week of treatment with antibiotics, and more minor conduction disturbances usually resolve within six weeks. These patients may initially require temporary cardiac pacing, but permanent cardiac pacing should be reserved for patients with a persistent third degree (complete) AV block following an adequate course of therapy for Lyme disease.
 
Most of the patients of third-degree AV block will require a permanent pacemaker if no reversible cause can be identified<ref>{{Cite journal|last=Task force members|first=|date=|title=2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA)|url=https://doi.org/10.1093/eurheartj/eht150|journal=Eur Heart J|volume=34|pages=2281-2329|via=}}</ref>. A Dual-chamber pacemaker is preferred to maintain AV synchrony in most patients due to the favorable hemodynamic benefits<ref>Brignole M, Auricchio A, Baron-Esquivias G, et al. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). ''Eur Heart J''. 2013;34(29):2281‐2329. doi:10.1093/eurheartj/eht150</ref>.  Implantable [[cardioverter-defibrillators]] should be considered in patients with complete AV block and significant left ventricle dysfunction.


==References==
==References==

Latest revision as of 10:48, 11 July 2021

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Zand, M.D.[2] Cafer Zorkun, M.D., Ph.D. [3] Raviteja Guddeti, M.B.B.S. [4] Soroush Seifirad, M.D.[5] Qasim Khurshid, M.B.B.S. [5]

Overview

The management of third-degree AV block depends on the severity of signs, symptoms, and the underlying cause. In symptomatic patients and with hemodynamic distress, pharmacological therapy should be initiated immediately to increase heart rate and cardiac output. Most of the patients who do not respond to pharmacologic therapy require a temporary pacemaker. After stabilizing the patients, assessment and treatment of potentially reversible causes should be done. Some patients without reversible cause or unidentified etiology require a permanent pacemaker.

Medical Therapy

Recommendations for Acute Management of Bradycardia Attributable to Atrioventricular Block
Symptomatic sinus bradycardia or atrioventricular block

Atropine 0.5-1 mg IV (may be repeated every 3-5 min to a maximum dose of 3 mg)
Dopamine 5 to 20 mcg/kg/min IV, starting at 5 mcg/kg/min and increasing by 5 mcg/kg/min every 2 min
Dosages of >20 mcg/kg/min may lead to vasoconstriction or arrhythmias

Isoproterenol 20-60 mcg IV bolus followed doses of 10-20 mcg, or infusion of 1-20 mcg/min based on heart rate response
Monitoring of ischemic chest pain

Epinephrine 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to desired effect

Second or third degree atrioventricular block associated acute inferior MI :

Aminophylline 250-mg IV bolus

Calcium channel blocker overdose

❑ 10% calcium chloride 1-2 g IV every 10-20 min or an infusion of 0.2-0.4 mL/kg/h
❑ 10% calcium gluconate 3-6 g IV every 10-20 min or an infusion at 0.6-1.2 mL/kg/h

Betablocker or Calcium channel blocker overdose

Glucagon 3-10 mg IV with infusion of 3-5 mg/h
❑ High dose insulin therapy IV bolus of 1 unit/kg followed by an infusion of 0.5 units/kg/h
Checking potassium and glocagon level

Digoxin overdose

Digoxin antibody fragment
Every vial for 0.5 mg of digoxin, over 30 min, maybe repeated

❑ Dosage is dependent on the amount ingested or known digoxin concentration

Post heart transplant

Aminophylline 6 mg/kg in 100-200 mL of IV fluid over 20-30 min
Theophylline 300 mg IV, followed by oral dose of 5-10 mg/kg/d
Therapeutic serum level 10-20 mcg/mL, posttransplant dosages average 450 mg±100 mg/d

Spinal cord injury

Aminophylline 6 mg/kg in 100-200 mL of IVfluid over 20-30 min
Theophylline Oral dose of 5-10 mg/kg/d titrated to effect
Effective serum level 10-20 mcg/mL


The above table adopted from 2018 AHA/ACC/HRS Guideline[1]



Class IIa
"1 Digoxin Fab antibody fragment is recommended in patients presented with digoxin toxicity resulting in symptomatic bradycardia or hemodynamic compromised. (Level of Evidence C)"
Class III
"2 Dialysis is not benefit in patients presented with bradycardia associated digoxin toxicity (Level of Evidence C)"











Recommendations for Acute Management of Reversible Causes of Bradycardia Attributable to Atrioventricular Block
Medical therapy (Class I, Level of Evidence B):

❑ In patients with transient or reversible causes of atrioventricular block including Lyme carditis or drug toxicity, medical therapy and transient pace maker insertion is recommended before making decision for implantation of PPM

PPM implantation ( Class IIa, Level of Evidence B) :

❑ In patients with symptomatic second-degree or third-degree atrioventricular block who are on chronic stable doses of medically necessary antiarrhythmic or beta-blocker therapy, PPM is recommended without further evaluation about drug washout or reversibility
❑ In patients with second-degree or third-degree atrioventricular block associated with cardiac sarcoidosis, PPM with defibrillation is recommended if life expectancy > 1 year, without further evaluation about reversibility

PPM implantation : (Class IIb, Level of Evidence C)

❑ In patients with symptomatic second-degree or third-degree atrioventricular block associated with thyroid function abnormalities but without clinical myxedema, PPM is recommended without further evaluation about reversibility

Abbreviations: PPM: Permanent pacemaker;

The above table adopted from 2018 AHA/ACC/HRS Guideline[1]

Notes


Recommendations for acute medical therapy for bradycardia associated atrioventricular block
Medical therapy (Class IIa, Level of Evidence C):

Atropine is reasonable for patients with symptomatic bradycardia associated second-degree or third degree atrioventricular block at the atrioventricular nodal level

Medical therapy (Class IIb, Level of Evidence B):

Beta adrenergic agonist such as isoproterenol, dopamine, dobutamine is recommended for symptomatic bradycardia associated second degree or third degree atrioventricular block with low likehood of ischemia

Medical therapy (Class IIb, Level of Evidence C):

Aminophylline is recommended for symptomatic bradycardia associated second or third degree atrioventricular block in the setting of acute inferior MI

Comment

References

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