Approach
• Follow ACLS protocols for anyone unstable or severely symptomatic (CP, SOB, AMS)
• Anticipate need for external/transvenous pacing & cardiology consult early
• Always obtain ECG & rhythm strip
• Medication hx is crucial
• In children, be highly suspicious of toxic ingestion
• In neonates, consider congenital cardiac dz
Definition
• HR <60 in an adult, <80 in a child <15 y/o, <100 in an infant <1 y/o. Caused by depressed function of the SA node or conduction system block/delay.
Sinus Bradycardia (NEJM 2000;342:703)
History
• Fatigue, syncope/presyncope, DOE, medication hx (esp βBs)
Differential
• Physiologic (athletic young adults), medications (nodal agents), hypothyroidism, ↑ vagal tone (including inferior MI), hypothermia, ↑ ICP
Evaluation
• ECG (HR <60 in adults, nl PR intervals, P wave preceding each QRS), rhythm strip
Treatment
• Asymptomatic bradycardia does not require tx. Tx only if symptomatic or life-threatening cause is suspected w/ atropine &/or pacing.
Disposition
• Admit anyone who is symptomatic
SA Node Block/Escape Rhythm
History
• Same as for sinus bradycardia
Differential
• Same as for sinus bradycardia. Also a/w ↑ K, ↑ vagal tone.
Evaluation
• ECG (absent atrial depolarization & missing P waves), rhythm strip, lytes, consider TSH, cardiac markers
Treatment
• Asymptomatic bradycardia does not require tx. Tx only if symptomatic or life-threatening cause is suspected.
Disposition
• Admit anyone who is symptomatic
Sinus Node Dysfunction (Sick Sinus Syndrome/Tachy–Brady Syndrome)
Definition
• Sinus node dysfxn includes a series of ECG abnormalities characterized by failure to generate appropriate cardiac potentials from the sinus node
• In sick sinus syndrome, there are frequent long sinus pauses that may degenerate to absent atrial depolarization for a period of time before the resumption of regular cardiac conduction (sinus arrest)
• In tachy–brady syndrome, episodes of sinus bradycardia or sinus arrest are interspersed w/ episodes of supraventricular tachycardia (often AF)
History
• Syncope, presyncope, fatigue, weakness, DOE, palpitations
• Typically observed in 70–80 y/o, suggesting age-related degeneration
Differential
• Consider other life-threatening arrhythmias
Evaluation
• ECG (frequent sinus pauses, bradycardia/tachycardia rhythms); consider electrolytes, cardiac markers, CBC; Holter or event monitoring
Treatment
• Acute tx only for symptomatic or life-threatening arrhythmia; ultimately may require combination of rate control for tachycardia & PPM for bradycardia
Disposition
• Admit anyone who is symptomatic for permanent PM placement
• If minimal or no sxs are present, d/c home w/ close f/u