Rosen & Barkin's 5-Minute Emergency Medicine Consult (87 page)

• Verapamil is not recommended in infants and young children as it is associated with a low cardiac output and serious cardiovascular compromise.
  
• Digoxin is the 1st-line drug therapy for pediatric atrial flutter.
  
• Consider cardioversion as 1st-line therapy in neonates.
  

• Amiodarone: 150 mg IV over 10 min, then continuous infusion at 1 mg/min for 6 hr, then 0.5 mg/min infusion over 18 hr; supplemental 150 mg infusions can be dosed PRN to a max. daily dose of 2.2 g (peds: 5 mg/kg IV loading dose over 20–60 min, may repeat to max. of 15 mg/kg/d IV)
  
• Adenosine: 6 mg IV × 1. May give 12 mg IV q1–2min × 2 if no conversion. Give all doses IV push
  
• Atenolol: 5 mg IV over 5 min, may repeat in 10 min if tolerated, then 50 mg PO q12h
  
• Digoxin: Loading dose 8–12 Ug/kg lean body weight, half of which is administered initially over 5 min, and remaining portion at 25% fractions at 4–8 hr intervals (peds: 8–12 μg/kg)
  
• Diltiazem: 0.25 mg/kg IV over 2 min followed in 15 min by 0.35 mg/kg IV over 2 min, maintenance infusion of 10–15 mg/h titrated to heart rate
  
• Dofetilide: CrCl >60 mL/min and QTc 440 msec or less) initial dose 500 μg ORALLY twice daily; determine QTc 2–3 h after 1st dose; if QTc increases by more than 15% OR is >500 msec (550 msec in patients with ventricular conduction abnormalities), reduce dose to 250 μg ORALLY twice daily; MAX. dose 500 μg ORALLY twice daily
  
• Esmolol: 0.5 mg/kg over 1 min; maintenance infusion at 0.05 mg/kg/min; can repeat loading dose and increase in increments of 0.05 mg/kg/min q4min up to 0.3 mg/kg/min
  
• Flecainide: A single dose of flecainide 300 mg (body weight 70 kg or greater), and flecainide 200 mg (body weight <70 kg) [3]; prior to antiarrhythmic initiation, a β-blocker or nondihydropyridine calcium channel antagonist should be administered to prevent rapid AV conduction if atrial flutter occurs
  
• Ibutilide: 1 mg IV over 10 min for patients >60 kg; 0.01 mg/kg IV for patients <60 kg infused over 10 min; dose can be repeated once if normal sinus rhythm not restored within 10 min after infusion
  
• Magnesium sulfate: 1–2 g diluted in D5W over 5–60 min; slower rate preferable if patient is stable.
  
• Metoprolol: 5 mg IV push over 5 min at 5 min intervals to total of 15 mg, then 50 mg PO BID
  
• Procainamide: 20 mg/min until arrhythmia suppressed, hypotension, QRS prolongation of 50%, or total of 17 mg/kg; may be given at rate up to 50 mg/min (peds: 15 mg/kg IV over 30 min, then 20–80 μg/kg/min continuous infusion)
  
• Propranolol: 0.5–1 mg over 1 min, repeated after 2 min up to a total dose of 0.1 mg/kg (peds: 0.01–0.15 mg/kg/dose slow IV push over 5 min, max. 1 mg/dose)
  
• Sotalol: 1–1.5 mg/kg over 5 min (US packaging recommends infusion over 5 h)
  
• Verapamil: 2.5–5.0 mg IV bolus over 2 min; may repeat with 5–10 mg q15–30min to a max. of 20–30 mg.
  

FOLLOW-UP

• New-onset atrial flutter requiring antidysrhythmics, rate control
  
• Symptomatic (i.e., chest pain that warrants a rule out or cardioversion)
  
• CHF
  

• New-onset atrial flutter who meet these criteria:
  
  • Rate or rhythm has been controlled
    
  • Underlying cause has been investigated and addressed
    
  • Anticoagulation has been initiated
    
  • Appropriate follow-up is arranged
    
• Chronic atrial flutter with good rate control and appropriate anticoagulation
  

Cardiologist: Radiofrequency ablation of atrial flutter emerging as treatment of choice for patients with symptomatic atrial flutter without identifiable reversible cause

• Be aware of WPW:
  
  • Do not use adenosine, β-blockers, calcium channel blockers, and digoxin (Class III can be harmful).
    
    • Can cause increased ventricular response, which can deteriorate to ventricular fibrillation
      
• Do not delay cardioversion in an unstable patient for IV placement.
  
• Use β-blockers with caution in patients with pulmonary disease or CHF.
  
• 4 major treatment issues:
  
  • Rate control
    
  • Prevention of systemic embolization
    
  • Reversion to sinus rhythm
    
  • Maintenance of sinus rhythm
    

• Clausen H, Theophilos T, Jackno K, et al. Paediatric arrhythmias in the emergency department.
  Emerg Med J.
  2012;29(9):732–737.
  
• Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the management of patients with atrial fibrillation. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines.
  J Am Coll Cardiol
  . 2006;48:e149.
  
• Lee G, Sanders P, Kalman JM. Catheter ablation of atrial arrhythmias: State of the art.
  Lancet
  . 2012;380(9852):1509–1519.
  
• Scheuermeyer FX, Grafstein E, Heilbron B, et al. Emergency department management and 1-year outcomes of patients with atrial flutter.
  Ann Emerg Med.
  2011;57(6):564–571.
  
• Stiell IG, Macle L; CCS Atrial Fibrillation Guidelines Committee. Canadian Cardiovascular Society atrial fibrillation guidelines 2010; management of recent-onset atrial fibrillation and flutter in the emergency department.
  Can J Cardiol
  . 2011;27(1):38–46.
  

CODES

427.32 Atrial flutter

BASICS

• Impaired conduction between the atrium and the ventricle through the AV node or His–Purkinje system
  
• 1st-degree AV block:
  
  • Prolonged conduction through the AV node
    
  • Ventricular impulses are not lost.
    
  • Generally benign, and occurs in 1.6% healthy adults.
    
• 2nd-degree AV block:
  
  • Marked by a failure of some atrial impulses to reach ventricles
    
  • Mobitz Type I (Wenckebach):
    
    • Usually secondary to conduction deficit in AV node.
      
    • Progressive prolongation of the pulse-rate (PR) interval until a nonconducted P-wave and a dropped QRS complex occur
      
    • Generally benign, but may be a complication of an inferior wall MI
      
  • Mobitz Type II:
    
    • Conduction deficit is usually below the level of the AV node.
      
    • PR intervals are constant until single or multiple beats are abruptly dropped.
      
    • High likelihood of progression to complete heart block
      
    • Worse prognosis if associated with an acute MI
      
    • Less common than Type I
      
• 3rd-degree AV block:
  
  • Also known as complete heart block
    
  • All atrial impulses are unable to reach the ventricular conducting system; a ventricular escape pacemaker then takes over, resulting in AV dissociation.
    
  • Constant PP and RR intervals with variable PR intervals because PP and RR intervals are independent of each other.
    
  • More severe symptoms occur when the block is lower in the conducting system.
    
  • If secondary to toxicologic agents, often resolves upon omission of offending toxin
    
  • Never a benign condition
    

• Essentially due to:
  
  • A structural lesion
    
  • Increase in inherent refractory period
    
  • Marked shortening of the supraventricular cycle
    
• MI:
  
  • 1st-degree block and Type I 2nd-degree AV block may be associated with an inferior wall MI:
    
    • These blocks are transient.
      
    • AV conduction usually returns to normal with no increased morbidity or mortality.
      
  • Type II 2nd-degree AV block may be associated with an anterior wall MI:
    
    • 5% anterior wall MIs are associated with AV blocks.
      
    • Increased mortality secondary to ventricular arrhythmias and left-heart failure
      
• Coronary artery disease:
  
  • Chronic ischemic injury can lead to fibrosis around the AV node
    
• Toxicologic:
  
  • Digoxin
    
  • β-blockers
    
  • Calcium-channel blockers
    
  • Amiodarone
    
  • Procainamide
    
  • Class 1C agents: Propafenone, encainide, flecainide
    
  • Clonidine
    
• Congenital
  
• Valvular heart disease
  
• Surgical trauma:
  
  • S/P coronary artery bypass graft or valvular replacement
    
• Increased vagal tone
  
• Infectious:
  
  • Syphilis
    
  • Diphtheria
    
  • Chagas disease
    
  • TB
    
  • Toxoplasmosis
    
  • Lyme disease
    
  • Myocarditis
    
  • Endocarditis
    
  • Rheumatic fever
    
  • Abscess formation in interventricular septum
    
• Collagen vascular diseases
  
• Infiltrative diseases:
  
  • Sarcoidosis
    
  • Amyloidosis
    
  • Hemochromatosis
    
• Cardiomyopathy
  
• Electrolyte disturbances:
  
  • Hyperkalemia
    
• Myxedema
  
• Hypothermia
  

• Occurs in children, but is often asymptomatic
  
• Associated mortality is highest in the neonatal period.
  
• Associated with:
  
  • Congenitally acquired maternal antibodies
    
  • Congenital heart disease
    
  • Infectious etiologies, such as rheumatic fever or myocarditis
    
• Be sure to consider potential toxic ingestions in pediatric patients with new AV block