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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) Pathology: - sinus node dysfunction is most often related to age-dependent progressive fibrosis 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) symptomatic (related to bradycardia) 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) d) permanent pacemaker 7) 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] 8) 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
  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