Rosen & Barkin's 5-Minute Emergency Medicine Consult (697 page)

DIAGNOSIS

• Asymptomatic
  
• Palpitations
  
• Lightheadedness
  
• Dyspnea
  
• Diaphoresis
  
• Dizziness
  
• Weakness
  
• Chest discomfort
  
• Angina
  
• Syncope
  
• Prominent neck veins
  
• Signs of instability:
  
  • Hypotension
    
  • Pulmonary edema
    
  • Chest pain
    
  • Mental status changes
    

• Acute onset of palpitations, lightheadedness, generalized weakness, or shortness of breath
  
• Sudden collapse, often preceded for minutes–hours by chest pain
  
• Prior history of cardiac disease common (ischemia, CHF)
  

Determine if the patient is hemodynamically stable:

• Assess mental status.
  
• Assess heart rate.
  
• Assess BP: Normal or hypotensive
  
• Cardiac exam
  

• ABCs
  
• Determination of unstable vs. stable patient
  
• Detailed history
  
• 12-lead EKG and rhythm strip to categorize the tachycardia
  

Studies should be ordered based on the presentation to evaluate underlying metabolic abnormalities or ischemia.

EKG:

• SVT:
  
  • Narrow complex, rate usually 130–160
    
  • Uniformity of polarity and amplitude
    
  • No P-waves visible
    
• AF:
  
  • Irregular, narrow QRS complex, rate <150--170 bpm
    
• 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 conducted P waves with varying pulse rate intervals
    
• VT:
  
  • QRS >0.12 sec and often >0.14 sec.
    
• Torsades de pointes:
  
  • Wide complex, ventricular rate >200 bpm
    
  • QRS structure displays an undulating axis, with the polarity of the complexes appearing to shift around the baseline.
    
  • Occurrence is often in short episodes of <90 sec.
    
• VF:
  
  • EKG shows oscillations without evidence of discrete QRST morphology.
    
  • Oscillations are usually irregular and occur at a rate of 150–300 bpm.
    
  • When the amplitude of most oscillations is 1 mm, the term “coarse” is used.
    
  • “Fine” VF is used for oscillations <1 mm.
    

TREATMENT

Cardiopulmonary resuscitation if pulseless

• IV access
  
• Oxygen
  
• Cardiac monitor
  
• Determine rhythm
  

• Irregular narrow complex (A fib):
  
  • Rate control
    
  • β-Blockers or calcium channel blockers
    
  • Anticoagulation if onset is >24 hr
    
  • Cardioversion for
    severe
    hemodynamic compromise
    
• Regular narrow-complex tachydysrhythmia:
  
  • Vagal maneuvers occasionally terminate the dysrhythmia:
    
    • Beware of carotid disease in elderly.
      
  • Adenosine:
    
    • May be diagnostic, revealing underlying AF/atrial flutter
      
• Stable wide-complex tachycardia:
  
  • Determine whether VT or SVT with aberrancy
    
  • Administration of AV nodal-blocking agents (verapamil, adenosine) may result in VF:
    
    • With WPW, use amiodarone, flecainide, procainamide, or DC cardioversion.
      
  • Electrical cardioversion should be utilized when mechanism unknown.
    
  • Antidysrhythmic drugs include procainamide and amiodarone.
    
• Torsades de pointes:
  
  • Magnesium, overdrive pacing, amiodarone
    
  • Correct underlying abnormal electrolytes.
    
  • Consider repletion of serum K to 4.5.
    
• Polymorphic VT (variable QRS morphology):
  
  • Ejection fraction (EF) normal:
    
    • β-Blockers, lidocaine, amiodarone, or procainamide
      
  • EF abnormal:
    
    • Amiodarone or lidocaine; then synchronized cardioversion
      
  • Treat ischemia and correct electrolytes.
    
• Monomorphic VT:
  
  • EF normal:
    
    • Procainamide preferred to amiodarone, sotalol, lidocaine; synchronized cardioversion
      
  • EF abnormal:
    
    • Amiodarone or lidocaine
      
    • Procainamide with caution as may cause hypotension; synchronized cardioversion
      
• VF or pulseless VT:
  
  • Treatment per ACLS protocol
    

• Adenosine: 6 mg (peds: 0.1 mg/kg up to 6 mg) rapid IV push; 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:
  
  • VT/SVT with pulse:
    150 mg IV over 10 min (peds: 5 mg/kg IV over 20--60 min, redose up to 15 mg/kg, 300 mg max), then 1 mg/min for 6 hr and 0.5 mg/min for next 18 hr.
    
  • VF/pulseless VT:
    300 mg IV push (peds: 5 mg/kg IV), may give 150 mg IV push 3--5 min after if no response (peds: redose up to 15 mg/kg or 300 mg max), followed by infusion as above.
    
• 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
  
• Epinephrine: 1 mg (peds: 0.01 mg/kg) IV push q3–5min; 2.5 mg (peds: 0.1 mg/kg) endotracheally q3–5min
  
• Lidocaine: 1–1.5 mg/kg (100 mg) (peds: 1 mg/kg) IV push, may repeat q5–10min, max. dose 3 mg/kg
  
• Magnesium sulfate: 2 g diluted in 100 mL D
  ₅
  W IV over 2 min (peds: 25–50 mg/kg, max. 2 g, IV over 10–20 min)
  
• Metoprolol: 5–15 mg slow IV push at 5-min intervals to total of 15 mg
  
• Procainamide:
  
  • VF/pulseless VT
    : 30 mg/min (peds: Not recommended) IV load until rhythm resolves, hypotension, QRS widens >50% or max. 17 mg/kg, then 1–4 mg/min IV
    
  • Perfusing VT
    : 20 mg/min (peds: 15 mg/kg IV over 30–60 min) IV load until rhythm resolves, hypotension, QRS widens >50% or max. 17 mg/kg, then 1–4 mg/min IV
    
  • SVT
    : 15–17 mg/kg IV at 20–30 mg/min
    or
    100 mg IV q5min slow IV push until rhythm resolves or max. dose 1,000 mg (peds: 3–6 mg/kg IV over 5 min, max. 100 mg/dose, may repeat q5–10min as needed to total dose 15 mg/kg)
    
• Vasopressin: 40 U (peds: Not recommended) IV push once
  

FOLLOW-UP

• VT or VF
  
• Possible cardiac ischemic event
  
• Persistent SVT
  
• Underlying metabolic abnormalities
  

Terminated supraventricular rhythm without organ hypoperfusion

Electrophysiologic testing:

• Diagnostic but not required emergently
  
• Determines therapy for accessory pathways
  

• Always suspect a ventricular rhythm with a wide complex rhythm, especially in the older patient.
  
• Antidysrhythmic administration may increase success rate of cardioversion.
  
• Rapid, uninterrupted chest compressions may increase the success rate of defibrillation for a patient with a pulseless rhythm.
  

• Anderson BR, Vetter VL. Arrhythmogenic causes of chest pain in children.
  Pediatr Clin North Am.
  2010;57:1305–1329.
  
• Hood RE, Shorofsky SR. Management of arrhythmias in the emergency department.
  Cardiol Clin
  . 2006;24:125–133.
  
• Link MS. Clinical practice. Evaluation and initial treatment of supraventricular tachycardia.
  N Eng J Med.
  2012;367(15):1438–1448.
  
• Neumar RW, Otto CW, Link MS, et al. Part 8: Adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
  Circulation
  . 2010;122(18 suppl 3):S729–S767.
  
• Roberts-Thomson KC, Lau DH, Sanders P. The diagnosis and management of ventricular arrhythmias.
  Nat Rev Cardiol.
  2011;8:311–321.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Atrial Fibrillation
  
• Supraventricular Tachycardia
  
• Ventricular Tachycardia
  

CODES