Tachycardia/Palpitations

Tachycardia/Palpitations: Excerpt from In A Page: Pediatric Signs and Symptoms

Most tachycardias in children are supraventricular and well tolerated, allowing time for proper evaluation and diagnosis. Cardiovascular collapse is rare but more common in those with a history of congenital heart disease and/or cardiac surgery.

Differential Diagnosis

• Sinus tachycardia
  –Most common cause of a fast heart rate
  –Normal response to stress (fever, pain, anxiety, dehydration, exercise, anemia, caffeine, tobacco, albuterol)
  –<180 beats/min and variable; ECG shows an upright P wave in lead I and AVF

• Supraventricular tachycardia (SVT)
  –Most common pathologic cause of tachycardia/palpitations in children
  –Narrow QRS complex (<0.08 seconds)
  –Almost all hemodynamically stable
  –Often paroxysmal
  –Usually AV re-entry or AV node re-entry; both have HR >180 and intermittent sudden onset and resolution

• AV re-entry
  –Involves an accessory electrical bypass tract connecting the atrium and ventricle (thereby “bypassing” the AV node)
  –Often associated with Wolff-Parkinson-White (WPW) syndrome (short PR interval, widened QRS interval, “delta” wave)
  –Most common in <10 years of age

• AV node re-entry
  –Involves re-entry within the AV node
  –Most common in >10 yrs of age

• Atrial fibrillation/flutter
  –Occurs almost exclusively in patients with underlying congenital heart disease
  –Macro (flutter) or micro (fibrillation) re-entry circuits within the atrium, usually around an old surgical scar
  –Common in patients status post-Fontan or Mustard-Senning procedures

• Ectopic/multifocal atrial tachycardia
  –Involves one or more automatic electrical foci in the atrium causing irregular tachycardia with a heart rate <180
  –The tachycardia has a slow onset and resolution

• Wide-complex tachycardia
  –Assume ventricular tachycardia until proven otherwise
  –SVT with bundle branch block (either permanent or rate-related)
  –Antidromic WPW: Re-entry loop in which the ventricle is depolarized via the bypass tract, creating a wide-complex tachycardia

Workup and Diagnosis

• History
  –Onset (sudden vs slow acceleration), activity at time of onset, duration, regularity of rhythm, pulse rate, resolution (sudden vs slow; with vagal maneuvers)
  –Symptoms during tachycardia: Chest pain, pallor, diaphoresis, syncope
  –History of underlying congenital heart disease
  –Medication use: Caffeine, tobacco, albuterol
  –Underlying medical condition: Fever, pain, anxiety, dehydration, anemia, thyrotoxicosis
  • Physical exam
    –Evaluate cardiovascular stability (BP, perfusion, mental status, tachypnea)
    –All unstable patients with a fast heart rate require electrical cardioversion
    –Rarely, chronic incessant tachycardias can cause cardiomyopathy with congestive heart failure
  • 12-lead ECG
    –During tachycardia: Narrow vs. wide complex, regular vs. irregular rhythm, P wave axis, QRS wave
    –Baseline: Evaluate for WPW, prolonged QTc, bundle
  • branch block
    –During therapy: Record ECG while giving adenosine
  • 24-hour Holter monitor for daily symptoms
  • 30-day event monitor for intermittent symptoms (recording activated by patient when symptoms occur)
  • Exercise testing with ECG monitor for patients with symptoms only during exercise

  Treatment

• Sinus tachycardia: Treat underlying cause
  • Acute therapy for SVT
    –Vagal maneuvers increase vagal tone at AV node, lengthening the refractory period and breaking re-entry SVT: Ice to face (<1 year old), blowing hard on thumb (toddler/child), carotid massage (teenager)
    –Adenosine: Increases refractory period of AV node better than vagal maneuvers by causing temporary AV block that breaks re-entry SVT; short (10 sec) half-life, so must give fast via IV push; side effects include hypotension (transient), chest tightness/pain, sense of “impending doom”
    –Synchronized cardioversion all unstable tachycardias (especially V-fib and pulseless V-tach)
  • Chronic therapy for re-entry SVT
    –β -blockers, digoxin (not in WPW), calcium channel blockers (not if <1 year old), other antiarrhythmics
    –Ablation of bypass tract via cardiac catheterization
  >>>>>>

Book Source Details

• Book Title: In A Page: Pediatric Signs and Symptoms
• Author(s): Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan
• Year of Publication: 2007
• Copyright Details: In A Page: Pediatric Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: In A Page: Pediatric Signs and Symptoms Authors: Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-4051-0427-9

 » Next page: MURMURS (Differential Diagnosis in Primary Care)

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