Sinus Bradycardia | Bradyarrhythmias - MedSchool
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Bradyarrhythmias
 
 
Bradyarrhythmias
Sinus bradycardia is initiated by the sinus node, and occurs in the setting of reduced automaticity due to either intrinsic or extrinsic causes.
 

Sinus Bradycardia

 
 

Overview

  • Sinus bradycardia is initiated by the sinus node, and occurs in the setting of reduced automaticity due to either intrinsic or extrinsic causes.
    • Look For

    • Decreased heart rate - <60bpm (or 50bpm when asleep)
    • Regular rhythm - normal PR interval with P waves preceding each QRS complex
    • Normal axis - positive P waves in leads I and II
    •  
    • Causes of Sinus Bradycardia

    • Intrinsic

    • Idiopathic degeneration
    • Myocardial infarction
    • Infiltrative disease - sarcoidosis, amyloidosis, haemochromatosis
    • Connective tissue disease - SLE, scleroderma, RA
    • Cardiac surgery - valvular surgery, correction of congenital heart disease
    • Infections - Lyme disease, endocarditis
    • Extrinsic

    • Physiologic - sleep, athletes
    • Autonomic - neurocardiogenic syncope, carotid sinus hypersensitivity
    • Drugs - beta blockers, calcium channel blockers, digoxin, adenosine, flecainide, ivabradine, clonidine, acetylcholinesterase inhibitors
    • Hypothyroidism
    • Hypothermia
    • Hyperkalaemia
    • Obstructive sleep apnoea
    • Raised intracranial pressure
Last updated on December 31st, 2018
 
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Read More...

Adan V, Crown LA. Diagnosis and treatment of sick sinus syndrome. American family physician. 2003 Apr;67(8):1725-32.
 Mangrum JM, DiMarco JP. The evaluation and management of bradycardia. New England Journal of Medicine. 2000 Mar 9;342(10):703-9.
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