Tachycardia; Stable Narrow Complex Irregular

1. Evaluate ABC's
   • Confirm stability, pulses, adequate blood pressure, good skin signs and mentation to proceed with this algorithm.
2. Early measures:
   • Apply oxygen
   • Make sure defibrillator present (in case stability changes)
   • Establish IV
   • Monitors (Rhythm, Oximetry, BP)
   • Obtain 12 lead EKG
   • Code cart
3. Obtain history and perform physical examination and consider causes:
   • Atrial fibrillation, atrial flutter or MAT (multifocal atrial Tachycardia )
   • Acute myocardial infarction, pulmonary embolus
   • Hypovolemia/Hypoxia/Hypothermia
   • Metabolic: Thyroid disease, hyper/hypokalemia, hypercalcemia, acidosis
   • Hypoglycemia
   • Drugs: Cocaine, Amphetamines, Decongestants, Ephedra, Ginseng
   • Pneumothorax or Tamponade
   • Cardiomyopathy/Valvular heart disease
   • COPD
   • Carbon monoxide exposure
   • Alcohol related ("Holiday heart")
   • Sepsis/Pneumonia
   • WPW [beware don't use drugs if WPW]
4. Treatment for stable irregular narrow complex tachycardia.
   • The goal is rate control.
   • Choose 1 of the following (dosing listed below):
   • CCB's: Diltiazem or verapamil
   • Beta Blockers: Metoprolol, atenolol, esmolol, propranolol

   Note: Avoid beta blockers in patients with CHF or pulmonary disease

   Diltiazem: 0.25 mg/kg [Max 20 mg] IV over 2 minutes; may repeat with 0.35 mg/kg [Max 25 mg] IV in 15 minutes. May start infusion 5-15 mg/hr after either bolus.
   Verapamil: 2.5-5 mg IV over 2 minutes; may repeat with 5-10 mg IV in 15-30 minutes until maximum cumulative dose of 20 mg given if needed.
   Metoprolol: 5 mg given slow IV every 5 minutes × 3 doses.
   Atenolol: 5 mg slow IV, may repeat in 10 minutes.
   Esmolol: Loading dose of 500 mcg/kg given over 1 minute then 50 mcg/kg/minute x 4 minutes. If inadequate response, reload with 500 mcg/kg given over 1 minute and follow this with an increased rate of infusion of 100 mcg/kg/minute and adjust as needed (maximum rate is 300 mcg/kg/minute).
   Propranolol: 0.1 mg/kg divided into 3 equal doses, each given IV at 2-3 minute intervals. May repeat the total dose × 1 if not successful.
   
   Additional Treatment Note
   For Afib with Rapid Response; Magnesium 1-2 grams in D5W over 30-60 minutes may be beneficial.
5. Standard laboratory evaluation (if indicated):
   • CBC, Electrolytes, TSH, Cardiac enzymes and toxicology testing
   • CXR
   • EKG pre and post conversion (if conversion occurs)
6. Consultation and/or admission to hospital if indicated.

Note:
For ACLS purposes narrow complex tachycardia is categorized into "Regular" or "Irregular" rhythm.

Regular

• Sinus Tachycardia: P waves present (don't treat this with ACLS drugs)
• SVT: Regular, rate typically 150-220/min
• Junctional tachycardia: May occasionally be narrow complex
• Atrial flutter: If rapid rate, may appear regular and similar to SVT

Irregular

• Atrial fibrillation
• Atrial flutter
• Multifocal atrial Tachycardia (MAT)

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