Disability: Decreased level of consciousness, irritability, lethargy.
Exposure: Do not evaluate temperature until ABCs are supported.
EKG:
No beat-to-beat variability with activity rate > 220/min in infants; > 180/min in children
P waves are absent or abnormal
PR interval generally not measurable, since P waves absent or buried in QRS complex
QRS complex usually narrow, rarely wide
Wide complex SVT may be hard to differentiate from ventricular tachycardia (VT) unless a child has a history of SVT with aberrant conduction, such as a bundle branch block; treat tachycardia with a wide QRS complex as VT
Atrial Fibrillation
Narrow complex tachyarrhythmia
Pulse is irregularly irregular
P wave may be difficult to discern, decoupled from QRS complex
Atrial Flutter
Narrow complex tachyarrhythmia
May develop congenitally, postoperatively,or in children whose hearts are normal
AV conduction varies
Atrial rate may be >300/minute, while ventricular rate is slower
ECG reveals “sawtooth” pattern of P waves
Ventricular Tachycardia (VTach)
Impulses originate in the ventricles
Wide complex QRS complex
Uncommon in children
May deteriorate into pulseless VTach or ventricular fibrillation (VF)
May occur due to genetics, cardiac surgery, long QT syndrome, cardiac diseases, electrolyte imbalances, and drugs
Stimulant drugs and tricyclic antidepressants may cause VT
May be difficult to differentiate from SVT with aberrant conduction
Unless a child has a history of SVT with aberrant conduction, initially treat wide QRS complex tachycardia dysrhythmias as VT
HR 120 to >200/minute
Wide (>0.09 second) QRS complex
P waves may not be visible;if present, may not be related to QRS complexes
T waves have opposite polarity from QRS complexes
AV conduction varies
Pulse is irregularly irregular
P wave may be difficult to discern, decoupled from QRS complex
Torsades de pointes
Specific type of ventricular tachycardia (VTach)
Complexes are polymorphic ( multiple shapes) on ECG
Phrase means “turning on a point”
HR= 150-250/minute
May be intermittent rhythm
Evaluate QT interval if rhythm reverts to sinus
Underlying causes include genetically acquired long QT syndrome, hypomagnesemia, hypokalemia, and drug toxicities
Drugs which may cause torsades include antiarrhythmic agents, tricyclic antidepressants, calcium channel blockers, and phenothiazines
Sudden death may occur secondary to primary VFib or torsades de pointes
Tachycardia Management
Vagal Maneuvers
Indicated if a child has a narrow complex tachycardia and is stable
Used while preparations are made for cardioversion
Rationale: The heart rate decreases when the vagal nerve is stimulated in infants and children; it may restore SVT to NSR
Methods
Ice maybe applied to an infant’s or child’s upper half of face for 15-20 seconds; take care not to occlude the nose or mouth
Children may perform a Valsalva maneuver by blowing through a straw
Carotid sinus massage may be utilized in older children
Do not apply ocular pressure as a vagal maneuver, as eye damage may occur
Adenosine
May help to distinguish atrial flutter from SVT. A 10- to 15-second period of bradycardia, asystole, or 3rd degree heart block may ensue after administration.
Must give rapidly. The drug’s half-life is less than 10 seconds.
Provide continuous ECG monitoring during administration.
Initial dose= 0.1 mg/kg bolus. Maximum initial dose is 6 mg.
If initial dose fails, administer 1 dose of 0.2mg/kg (maximum dose 12 mg).
Administer a rapid flush of 5-10 mLnormal saline after each dose.
Amiodarone
Used to treat multiple types of tachyarrhythmias. Prolongs QT interval.
Rare side effects include bradycardia
Administer slowly, as rapid administration may result in heart block, polymorphic VT, or hypotension.
Provide drug at a slower rate than used during cardiac arrest due to risk of hypotension.
Monitor BP frequently during administration.
Obtain expert advice for administration.
For SVT and ventricular arrhythmias with poor perfusion; administer a loading dose of 5mg/kg over 20-60 minutes.
Maximum initial dose = 300 mg.
Repeat dose =5-15mg/kg per 24 hours.
Do not exceed 2.2 grams in 24 hours.
Additional Treatments
Procainamide: Treats a wide range of atrial and ventricular arrhythmias, including, SVT, VT, atrial flutter, and atrial fibrillation. Must be given slowly. Monitor BP. Obtain expert advice when using.
Lidocaine: Use to treat stable VT. Not effective for supraventricular arrhythmias. Administer a bolus, followed by a continuous infusion. Lidocaine toxicity may occur in patients with prolonged low cardiac output or renal failure. Do not give if high degree heart block or bradycardia is present.
Magnesium sulfate: Use to treat hypomagnesemia or Torsades de pointes.
Digoxin: Slows the pulse and improves cardiac output.
Beta blockers.
Transcutaneous pacing (overdrive pacing).
Cardioversion
Synchronized cardioversion is used to treat hemodynamically unstable children who have tachyarrhythmias and palpable pulses.
Unsynchronized shocks are delivered during cardiac arrest, as no QRS complexes are present. Synchronized shocks delivered during cardioversion are timed to be delivered on the R portion of the QRS complex.
SVT, atrial flutter, and VTach with a pulse are treated with cardioversion.
Synchronized cardioversion is performed with a defibrillator set to deliver a shock at a lower energy dose than the dose used for defibrillation.
Consult with a pediatric cardiologist if VFib is suspected.
Elective cardioversion may be used to treat hemodynamically stable children with tachyarrhythmias if advised by a pediatric cardiologist.
VF often develops during the T wave portion of the electrical impulse. Delivery of a shock on the R portion of the QRS portion helps to prevent VF.
While cardioverting, a delay may occur in shock delivery as the machine waits to sense the R wave.
Most defibrillators require that the synchronization (SYNC) button be activated each time a shock is delivered, as the charge level automatically resets to the charge given for defibrillation.
R waves may be difficult to sense. Turning up the amplitude on the monitor or changing to a different lead may make them more recognizable by the defibrillator.
Preparing for synchronization may take extra time.
Cardioversion is painful.
If the child is hemodynamically stable, obtain vascular access and provide analgesia prior to cardioversion. If unstable, perform cardioversion without obtaining vascular access or administering analgesia.
The initial energy dose for cardioversion is 0.5-1J/kg. If ineffective, increase the dose to 2J/kg for subsequent doses.
Procedure for performing cardioversion:
Turn on defibrillator.
Set lead switch to paddles. If monitor leads are used, set to leads I, II, or III.
Apply the largest leads to paddles that can fit on the child’s chest without them touching each other.
If using paddles, apply conductive gel or paste.
Ensure cables are attached to defibrillator.
Consider sedation.
Turn mode switch to SYNC.
Observe monitor for markers on R waves. Adjust monitor gain or switch to a different lead if R waves are not visible.
Select energy dose of 0.5-1 J/kg.
Announce, “Charging defibrillator.”
Press ‘charge’ on apex paddle or defibrillator controls.
When defibrillator is fully charged, announce, “I am going to shock.”
State and confirm that all providers are clear of the patient.
Press the shock button on the defibrillator or 2 paddle discharge buttons simultaneously.
Keep paddles in place until shock is delivered.
Check monitor.
If tachycardia persists, increase energy dose to 2J/kg.
Reset defibrillator to SYNC mode and recharge.
If VFib develops, begin CPR and prepare to deliver an unsynchronized shock.
