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Introduction ⬇

Recognizing sinus arrest

Rhythm

  • Regular except during arrest (irregular as result of missing complexes)

Rate

  • Usually within normal limits (60 to 100 beats/min) before arrest
  • Length or frequency of pause may result in bradycardia

P wave

  • Periodically absent, with entire PQRST complexes missing
  • When present, normal size and configuration
  • Precedes each QRS complex

PR interval

  • Within normal limits when a P wave is present
  • Constant when a P wave is present

QRS complex

  • Normal duration
  • Normal configuration
  • Absent during arrest

T wave

  • Normal size
  • Normal configuration
  • Absent during arrest

QT interval

  • Within normal limits
  • Absent during arrest

Other

  • The pause isn't a multiple of the underlying P-P intervals
  • Junctional escape beats may occur at end of pause


What Causes It ⬆ ⬇

  • Acute inferior-wall MI
  • Cardiac disorders such as acute myocarditis, cardiomyopathy, coronary artery disease (CAD), hypertensive heart disease
  • Acute infection
  • Sick sinus syndrome
  • Increased vagal tone or carotid sinus sensitivity
  • Sinus node disease
  • Amiodarone, beta-adrenergic blockers (metoprolol [Lopressor]), calcium channel blockers (verapamil [Calan]), digoxin (Lanoxin), quinidine, procainamide, salicylates, especially at excessive or toxic levels

What to Look for ⬆ ⬇

  • Absence of heart sounds and pulse during arrest
  • Absence of symptoms with short pauses
  • Evidence of decreased cardiac output with recurrent or prolonged pauses
    • Low blood pressure
    • Altered mental status
    • Cool, clammy skin
    • Syncope or near-syncope
    • Dizziness
    • Blurred vision

How It's Treated ⬆

  • No treatment is needed if the patient is asymptomatic.
  • As needed, discontinue drugs that affect SA node discharge or conduction, such as:
    • beta-adrenergic blockers
    • calcium channel blockers
    • digoxin
  • Protect the patient from the risk of injury, such as a fall, which may result from syncopal or near-syncopal episodes caused by a prolonged pause.
  • Atropine, epinephrine, or pacemaker for signs of circulatory collapse
  • Goal is adequate cardiac output and perfusion.