Health Dictionary
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Second degree AV block medical therapy
Introduction
Overview
Overview
Treatment for a Mobitz type I second-degree AV block (Wenckebach) is often not necessary. Occasionally Mobitz type 1 second degree AV blocks may result in bradycardia leading to hypotension and responds well to medications. If unresponsive to atropine or beta-adrenergic agonists, pacing (transcutaneous or transvenous) should be initiated for stabilization. If the patient is on any beta-blockers, calcium channel blockers or digoxin, the medications should be discontinued. All patients with Mobitz 1 block should be admitted and monitored. Treatment for a Mobitz type II involves initiating pacing as soon as this rhythm is identified. Mobitz type II second-degree AV blocks may imply structural damage to the AV conduction system. This rhythm often deteriorates into a complete heart block. These patients require transvenous pacing until a permanent pacemaker is placed. Unlike Mobitz type I second degree AV block (Wenckebach), Mobitz type II AV block often do not respond to atropine or beta-adrenergic agonists.
Medical Therapy
Medical Therapy
| Recommendations for acute medical therapy for bradycardia associated atrioventricular block |
| Atropine (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 |
| Beta adrenergic agonist (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 |
| Aminophylline (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 |
| The above table adopted from 2018 AHA/ACC/HRS Guideline[1] |
|---|
- 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.[2]
- 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. [3]
- 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.[4]
| 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) ❑ Isoproterenol 20-60 mcg IV bolus followed doses of 10-20 mcg, or infusion of 1-20 mcg/min based on heart rate response ❑ 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 |
| Betablocker or Calcium channel blocker overdose |
|
❑ Glucagon 3-10 mg IV with infusion of 3-5 mg/h |
| Digoxin overdose |
|
❑ Digoxin antibody fragment ❑ 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 |
| Spinal cord injury |
|
❑ Aminophylline 6 mg/kg in 100-200 mL of IVfluid over 20-30 min |
| The above table adopted from 2018 AHA/ACC/HRS Guideline[1] |
|---|
Mobitz I
- Patients with type I second degree AV block are usually asymptomatic and do not require treatment.[5][6].
- Correction of reversible causes of the block such as ischemia, medications, and vagotonic conditions should be addressed[7].
- Transvenous or transcutaneous Pacing may be needed to stabilize the patient when bradycardia is unresponsive to medications.[5]
Mobitz II
- Correction of reversible causes of the block such as ischemia, medications, and vagotonic conditions should be considered.[8].
- Patients may need immediate transvenous pacing until a permanent pacemaker is placed[5].
- Treatment in emergency situations are atropine, adrenergic agonists, epinephrine and an external pacer.[9][10].
References
References
- ↑ 1.0 1.1 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.
- ↑ Hatle L, Rokseth R (July 1971). “Conservative treatment of AV block in acute myocardial infarction. Results in 105 consecutive patients”. Br Heart J. 33 (4): 595–600. doi:10.1136/hrt.33.4.595. PMC 487219. PMID 5557475.
- ↑ 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 (March 2008). “A randomized controlled feasibility trial comparing safety and effectiveness of prehospital pacing versus conventional treatment: ‘PrePACE‘“. Resuscitation. 76 (3): 341–9. doi:10.1016/j.resuscitation.2007.08.008. PMC 7126680 Check
|pmc=value (help). PMID 17933452. - ↑ Hurley KF, Magee K, Green R (November 2015). “Aminophylline for bradyasystolic cardiac arrest in adults”. Cochrane Database Syst Rev (11): CD006781. doi:10.1002/14651858.CD006781.pub3. PMID 26593309.
- ↑ 5.0 5.1 5.2 Mangi MA, Jones WM, Napier L. PMID 29493981. Missing or empty
|title=(help) - ↑ Hisamura M, Taguchi H, Hiraide A (January 2016). “Mobitz type 1 second-degree atrioventricular block by triazolam and brotizolam overdose”. Acute Med Surg. 3 (1): 57–58. doi:10.1002/ams2.121. PMC 5667231. PMID 29123752.
- ↑ 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.
- ↑ 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.
- ↑ 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.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Zand, M.D.[2] Mohammed Salih, M.D. Cafer Zorkun, M.D., Ph.D. [3] Syed Musadiq Ali M.B.B.S.[4]