Rosen & Barkin's 5-Minute Emergency Medicine Consult (688 page)

• ABCs, assess stable vs. unstable
  
• History
  
• EKG
  

• CBC
  
• Electrolytes
  
• Cardiac enzymes, BNP
  
• Thyroid function (usually low yield)
  

• CXR:
  
  • Assess cardiac size
    
  • Evaluate for pulmonary process
    
  • More useful in AF/flutter
    

• EKG:
  
  • AF:
    
    • Atrial fibrillatory waves without discernable P-waves
      
    • Irregularly irregular ventricular rate of 100–220
      
  • Atrial flutter:
    
    • Regular atrial rate usually >300
      
    • Beat-to-beat uniformity of cycle length, polarity, and amplitude
      
    • Sawtooth flutter waves directed superiorly and most visible in leads II, III, aVF
      
    • AV block, usually 2:1, but occasionally greater or irregular
      
  • Multifocal atrial tachycardia:
    
    • 3 distinctly different P-waves with varying pulse rate intervals
      
  • Atrial tachycardia:
    
    • Rate of 100–200 bpm
      
    • P-wave precedes QRS and is morphologically different from the sinus P-wave.
      
  • Junctional tachycardia:
    
    • Usually 1:1 conduction, with ventricular rates equaling the atrial rate.
      
    • May be either paroxysmal or sustained
      
    • Ventricular rates >200 bpm in an adult suggest an accessory pathway syndrome such as WPW syndrome.
      
    • Absence of preceding P-waves
      
    • Often retrograde P-waves buried in the QRS
      

• Sinus tachycardia:
  
  • Sepsis
    
  • Hypovolemia
    
  • Pericardial tamponade
    
  • Acute MI
    
  • Drug intoxication
    
• Wide complex tachycardias:
  
  • Distinguish between supraventricular with aberrancy or ventricular origins.
    

TREATMENT

• Supplemental oxygen
  
• IV access
  
• Monitor
  

• IV access
  
• Oxygen
  
• Monitor
  

• AF/atrial flutter:
  
  • AF is most likely diagnosed when the rhythm is irregular
    
  • When unstable, then immediate synchronized cardioversion
    
  • When stable, rate control is a priority:
    
    • β-blockers or calcium channel blockers, amiodarone, and digoxin
      
    • Cardioversion in stable patients should not be attempted unless the dysrhythmia is known to be acute (<48 hr in duration) due to risk of embolism
      
• WPW syndrome:
  
  • Consider direct current cardioversion or amiodarone, flecainide, or procainamide.
    
  • Avoid AV node blocking agents such as adenosine, β-blockers, calcium channel blockers, and digoxin.
    
• In regular narrow complex SVTs:
  
  • Vagal maneuvers will occasionally terminate the dysrhythmia:
    
    • Carotid massage (although beware of carotid disease, especially in elderly)
      
    • Ice to face in children (mammalian diving reflex)
      
    • Valsalva maneuver
      
  • If this is unsuccessful, adenosine is the drug of choice.
    
  • Adenosine 6 mg will convert 60–80% of SVT
    
• Wide complex SVT:
  
  • Try to determine whether VT or SVT with aberrancy
    
  • If in doubt must be treated as VT
    
  • Brugada criteria may help identify VT (See “Ventricular Tachycardia”).
    
  • Verapamil is absolutely contraindicated.
    
  • Adenosine should be reserved for SVT with aberrancy and is rarely indicated.
    
  • Electrical cardioversion:
    
    • Fewer potential complications than antiarrhythmic drugs when mechanism unknown
      
  • Antidysrhythmic drugs:
    
    • IV procainamide and IV amiodarone
      
    • Lidocaine is less effective, although sometimes more readily available.
      
    • Bretylium lacks any evidence of efficacy.
      

• Synchronized cardioversion for unstable patient 0.5–1 J/kg
  
• SVT is the most common dysrhythmia seen in young adults and children without underlying heart disease:
  
  • Initial vagal maneuvers:
    
    • Infants: Ice/water bag to forehead × 15 sec
      
    • Children: Valsalva: “Blow into straw”
      
• Aberrant conduction:
  
  • WPW syndrome and AVNRT are the 2 most common forms of SVT seen in children.
    
• Use verapamil only >1 yr of age.
  

• Adenosine considered safe
  
• 2nd-line agents IV propranolol or metoprolol
  
• Avoid verapamil (maternal hypotension)
  
• Cardioversion is safe.
  

• Adenosine: 6 mg (peds: 0.1 mg/kg up to 6 mg) rapid IVP; if no response after 1–2 min, then 12 mg (peds: 0.2 mg/kg up to 12 mg), may repeat 12 mg (0.2 mg/kg)
  
• Amiodarone: Load with 15 mg/min IV over 10 min (peds: 5 mg/kg over 20–60 min), then 1 mg/min IV for 6 hr, then 1 mg/min IV for 6 hr, then 0.5 mg/min IV for 18 hr
  
• Digoxin: 0.5 mg IV initially, then 0.25 mg IV q4h
  
• Diltiazem: 0.25 mg/kg IV (usually 10–20 mg) over 2 min, followed in 15 min by 0.35 mg/kg IV over 2 min
  
• Esmolol: 0.5 mg/kg IV over 1 min; maintenance infusion, 0.05 mg/kg/min IV over 4 min, then 0.1–0.2 mg/kg/min IV continuously
  
• Lidocaine: 100 mg IV
  
• Metoprolol: 5–15 mg slow IV push at 5-min intervals to total of 15 mg
  
• Procainamide: 20–30 mg/min IV up to 17 mg/kg, may increase to 50 mg/min for more urgent situations
  
• Propranolol: 0.1 mg/kg div. into equal doses at 2–3-min intervals
  
• Sotalol: Load 10 mg/min IV up to 1–1.5 mg/kg body weight
  
• Verapamil: 2.5–5 mg IV bolus over 2 min; may repeat with 5–10 mg q15–30min to max. of 20 mg
  

FOLLOW-UP

• Possible cardiac ischemic event
  
• Persistent SVT
  
• Possible pre-excitation syndrome
  
• Other underlying metabolic abnormalities
  

Terminated rhythm without organ hypoperfusion

If there are no concerns for underlying cardiac disease or metabolic derangement, a patient with uncomplicated SVT that is successfully treated may be discharged to follow-up with a primary doctor or cardiologist.

The patient should return to the ED if feeling faint, dizzy, numbness or weakness of the face or limbs, or trouble seeing or speaking. Avoid high-risk activities (swimming, piloting, diving, etc.) until further evaluation.

• Valsalva maneuvers should, ideally, be attempted with the patient lying flat. Despite the modest likelihood of success, the maneuver is simple and efficient.
  
• AF is the most worrisome rhythm in patients with an accessory pathway such as WPW. At high ventricular rates, AF can appear deceptively regular, but should not be mistaken for benign SVT.
  
• When adenosine has no apparent effect, an escalating dose beyond 12–18 mg, is sometimes used. However, if any lower adenosine dose transiently slows the heart rhythm, but the fast rate quickly resumes, then an increased dose is not warranted and an alternative medication should be used.
  
• A wide complex tachycardia of uncertain etiology should be treated as VT, typically with amiodarone and potentially with procainamide if an accessory pathway is possible.
  
• Since procainamide can be administered at a maximum rate of 50 mg/min, it takes a minimum of 20 min to administer 1 g, or 30 min to administer 1.5 g. Therefore, request the medicine promptly to optimize timing of administration. If QRS widening or hypotension occur, slow the rate of administration or discontinue the medication.
  

• Colucci RA, Silver MJ, Shubrook J. Common types of supraventricular tachycardia: Diagnosis and management.
  Am Fam Physician
  . 2010;82(8):942–952.
  
• Hood RE, Shorofsky SR. Management of arrhythmias in the emergency department.
  Cardiol Clin
  . 2006;24:125–133.
  
• Katritsis DG, Camm AJ. Atrioventricular nodal reentrant tachycardia.
  Circulation
  . 2010;122:831–840.
  
• Link MS. Clinical practice. Evaluation and initial treatment of supraventricular tachycardia.
  N Engl J Med.
  2012;367(15):1438–1448.
  
• Manole MD, Saladino RA. Emergency department management of the pediatric patient with supraventricular tachycardia.
  Pediatr Emerg Care
  . 2007;23(3):176–189.
  
• Marill KA, Wolfram S, Desouza IS, et al. Adenosine for wide-complex tachycardia: Efficacy and safety.
  Crit Care Med
  . 2009;37(9):2512–2518.
  

See Also (Topic, Algorithm, Electronic Media Element)

Ventricular Tachycardia

CODES