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bradyarrhythmia (bradycardia)

A disturbances in cardiac rhythm that result in an abnormally slow heart rate, usually under 60/min. Etiology: 1) decreased sinus node automaticity (sinus bradycardia) 2) sinus node exit block 3) atrioventricular block - complete heart block 4) pharmaceutical agents a) cholinesterase inhibitors (sinus bradycardia) b) beta-blockers (AV nodal block) c) diltiazem, verapamil (AV nodal block) d) digoxin (AV nodal block) 5) sleep disturbance, obstructive sleep apnea [2] Pathology: - sinus node dysfunction is most often related to age-dependent progressive fibrosis - nocturnal bradycardia may be a sign of underlying sleep disturbance - high vagal tone resulting in Mobitz type 1 heart block at night [2] Special laboratory: - 12 lead ECG (all patients) Management: as indicated 1) assess, Airway, Breathing, Circulation (ABCs) 2) administer oxygen 3) establish IV access 4) 12 lead ECG 5) asymptomatic a) type II second degree AV block or type 3 heart block - transvenous pacer - transcutaneous pacemaker until transvenous pacemaker can be inserted b) 1st degree or type 1 second degree AV block - discontinue culprit medications as feasible, observe [3] 6) acutely symptomatic (related to sinus bradycardia, not AV block) a) atropine 0.5 mg IV push every 3-5 min up to 3 mg - unlikely to be useful for wide-complex bradyarrhythmia b) transcutaneous pacemaker (uncomfortable) - transvenous pacing is less uncomfortable (patient stable) c) a & b unsuccessful/unavailable - dopamine 5-20 ug/kg/min (IIb intervention) - epinephrine 2-20 ug/min (IIb intervention) - isoproterenol 2-10 ug/min (not indicated in cardiac arrest) 7) permanent pacemaker - chronically symptomatic - prevent recrurence of acutely symptomatic bradycardia 8) other recommendations [5] - nocturnal bradycardia is common - evaluate these patients for sleep apnea - left bundle branch block (LBBB) - evaluate for structural heart disease echocardiogram - irreversible second-degree Mobitz type II AV block or third-degree AV block should be paced - Wenckebach block: paced only if symptoms due to bradycardia - LV ejection fraction 36-50% with pacing >40% of the time - cardiac resynchronization therapy or His bundle pacing recommended - LBBB induced by transcatheter aortic-valve replacement (TAVR) is given a class IIb indication for pacing - do NOT place pacemaker for asymptomatic bradycardia [6] 9) patients or their legally defined surrogates have the right to refuse implantation of permanent pacemakers & to withdraw pacing, even if life threatening [5]

Related

cardiac pacemaker

Specific

asystole atrioventricular (AV) block sick sinus syndrome; atrial fibrillation with bradyarrhythmia; tachycardia-bradycardia syndrome sinoatrial exit block sinus bradycardia ventricular escape rhythm

General

cardiac arrhythmia

References

  1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 177, 179
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 18. American College of Physicians, Philadelphia 1998, 2018 - Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025
  3. Goldberger JJ et al. Significance of asymptomatic bradycardia for subsequent pacemaker implantation and mortality in patients >60 years of age. Am J Cardiol 2011 Sep 15; 108:857. PMID: 21757182
  4. Geriatric Review Syllabus, 7th edition Parada JT et al (eds) American Geriatrics Society, 2010
  5. 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: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. J Am Coll Cardiol. 2018 Oct 31. pii: S0735-1097(18)38984-8. PMID: 30412710 - Kusumoto FM, Schoenfeld MH, Barrett C et al. ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. J Am Coll Cardiol 2018 Nov 6; PMID: 30412709 https://www.sciencedirect.com/science/article/pii/S0735109718389848
  6. Diederichsen SZ et al. Prevalence and prognostic significance of bradyarrhythmias in patients screened for atrial fibrillation vs usual care: Post hoc analysis of the LOOP randomized clinical trial. JAMA Cardiol 2023 Feb 15; [e-pub]. PMID: 36790817 PMCID: PMC9932940 Free PMC article https://jamanetwork.com/journals/jamacardiology/fullarticle/2801362 - Schoenfeld MH, Patton KK. Incidental detection of bradycardia by implantable loop recorders - Unintended consequences. JAMA Cardiol 2023 Feb 15; [e-pub]. PMID: 36790795 https://jamanetwork.com/journals/jamacardiology/fullarticle/2801364
  7. Sidhu S, Marine JE. Evaluating and managing bradycardia. Trends Cardiovasc Med. 2020;30:265-272. PMID: 31311698
  8. 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. Circulation. 2019;140:e382-e482. PMID: 30586772