Tachycardia; Narrow Complex (Unstable)

Determine Patient Stability

Patient is considered unstable if there is hypotension, poor skin signs, shortness of breath, chest pain, evidence of CHF, or decreased mentation [or any other symptom felt to be caused by the bradycardia].

This protocol is for Narrow QRS 0.08 sec

1. Evaluate ABC's
   • Stabilize Airway/Breathing
   • Apply oxygen
   • Place cardioversion/defibrillation pads
   • Establish IV
   • Monitors (Rhythm, Oximetry, BP)
   • Obtain 12 lead EKG
   • Code cart
2. Obtain history and perform physical examination and consider causes:
   • Differential diagnosis includes:
   1. Sinus tachycardia
   • Infants usually <220 bpm
   • Children usually <180 bpm
   2. Supraventricular tachycardia (SVT )
   • Infants usually 220 bpm
   • Children usually 180 bpm
   • Consider Causes
   • Hypovolemia/Hypoxia/Hypothermia
   • Sepsis/Infections
   • Drugs: Cocaine, Amphetamines, Decongestants, Ephedra, Ginseng
   • Metabolic: Thyroid disease, hyper/hypokalemia, hypercalcemia, acidosis, hypoglycemia
   • Pneumothorax or Tamponade
   • Acute myocardial infarction, pulmonary embolus
   • Cardiomyopathy/Valvular heart disease
3. 
   3a) Sinus Tachycardia: Look for underlying cause and treat
   3b) SVT: Proceed to step 4 below
4. Treatment of SVT
   4a) Vagal maneuvers without delay
1. Valsalva (blow on obstructed straw)
2. Unilateral carotid massag
3. Ice to face

4b) Adenosine
• 0.1 mg/kg initial (Max 6 mg)
• 0.2 mg/kg subsequent (Max 12 mg)
• Administer to proximal vein when possible, using rapid IVP followed immediately with 5-20 mL saline flush. Extremity should be elevated.

4c) Synchronized Cardioversion
• This may be the initial therapy if the urgency does not allow for other maneuvers
• Synchronized cardioversion:
• 0.5-1 J/kg, may repeat at 2 J/kg
• Sedation if possible (agents such as Etomidate, Fentanyl or Midazolam are common choices)
• Pads on patient (or paddles)
• Press sync button (make sure to have 3 lead monitor leads attached to the defibrillator/cardiovertor)
• Confirm Joule setting appropriate
• Monitor for response to therapy; if needed, increase joules for subsequent shocks and make sure to press the sync button prior to each shock.
5. Patient in narrow complex tachycardia consistent with SVT, but not resolved with adenosine and vagal maneuvers, but not unstable enough to warrant synchronized cardioversion immediately.
   • Options include antiarrhythmic agents or sedation and cardioversion May utilize EITHER (not both) Amiodarone OR Procainamide
   1. *Amiodarone 5 mg/kg IV (Max 300 mg) over 20-60 minutes [Preferred] OR
   2. Procainamide 15 mg/kg IV over 30-60 minutes.
   * Amiodarone infusion can be repeated to a maximum of 15 mg/kg total cumulative dose if needed.
6. Standard laboratory evaluation (if indicated):
   • CBC, Electrolytes, TSH, Cardiac enzymes and toxicology testing
   • CXR
   • EKG pre and post conversion (if conversion occurs)
7. Consultation and admission to hospital if indicated.

Source: Circulation 2005;112. 2005 AHA Guidelines for CPR and ECC.