Atrial flutter

Background

• Supraventricular Tachycardia
  • Atrial re-entry circuit
• Defined by atrial rate of 250-350, classically 300

Clinical Features

• Asymptomatic
• Palpitations
• Fatigue
• Dyspnea
• Pre-syncope/syncope

Differential Diagnosis

• Can be difficult to distinguish from atrial fibrillation

Palpitations

• Arrhythmias:
  • Atrial fibrillation
  • Grouped beats on ECG (commonly misdx as A-fib)
    • Atrial bigeminy and trigeminy
    • Mobitz I or Mobitz II
  • Atrial flutter
  • SVT
  • Ventricular Tachycardia
  • Sick sinus syndrome
  • Multifocal atrial tachycardia
  • PVCs
  • Wolff–Parkinson–White syndrome (WPW)
  • Sinus node dysfunction
  • AV Block
  • Lown-Ganong-Levine Syndrome‎
  • Accelerated idioventricular rhythm
• Non-arrhythmic cardiac causes:
  • Cardiomyopathy
  • CHF
  • Mitral valve prolapse
  • Congenital heart disease
  • Pericarditis
  • Valvular disease
  • Pacemaker malfunction
  • Acute MI
• Psychiatric causes:
  • Anxiety disorder
  • Panic attack
• Drugs and Medications:
  • Alcohol
  • Caffeine
  • Meds (i.e. digitalis, theophylline)
  • Street drugs (i.e. cocaine)
  • Tobacco
• Misc
  • Hyperthyroidism

Evaluation

• ECG
• CBC
• Chem 7
• Magnesium level
• Troponin if patient has chest pain
• Cardiac Echo - if signs of new/worsening heart failure

Flutter with alternating 2:1 and 3:1 block.

Atrial flutter with variable block

ECG

• Narrow complex tachycardia
• Atrial rate near 300
• Flutter waves (sawtooth pattern) in inferior leads
• AV nodal conduction
  • 1:1 conduction can be unstable
    • Suggests pre-excitation, sympathetic excess, parasympathetic withdrawal, Class 1C anti-arrhythmic use
  • 2:1 conduction is most common
    • Suspect atrial flutter whenever ventricular rate is 150
  • conduction >2:1
    • More commonly even ratio
    • Suggests AV nodal blocking agents or AV node disease
  • Variable block
    • Difficult to distinguish from atrial fibrillation
    • Look for: R-R interval that is multiple of P-P interval and mathematical relationship between R-R intervals
    • A-fib is completely irregular with no relationship between intervals
• Amal Mattu recommends flipping ECG 180 to easily see inverted P waves or speed machine up to 50 mm/s to stretch out ECG

Types

• Type 1 (Typical Atrial Flutter)
  • Re-entry circuit of right atrium (IVC and tricuspid valve)
    • Anticlockwise circuit- 90% of cases
      • Inverted flutter waves in inferior leads
      • Positive flutter waves in V1
    • Clockwise circuit
      • Positive flutter waves in inferior leads
      • Inverted flutter waves in V1
• Type 2 (Atypical Atrial Flutter)
  • Does not meet criteria for typical atrial flutter
  • Less amenable to treatment

Management

Unstable

• Synchronized cardioversion
  • Atrial flutter - start at 50 J
  • Atrial fibrillation - start at 200 J
• Indications: ischemic chest pain, SBP < 90, acute pulmonary edema, altered mental status
• If shock does not work:

1. Verify not preexcitation
2. Increase diastolic BP to perfuse the heart
   • Push-dose phenylepherine
     • Will maintain BP when give rate-control medications
     • 50-200mcg q2-5min with goal DBP >60
3. Amiodarone 150mg over 10min (preferably through central venous access) OR diltiazem 2.5mg/min until HR<100 or max 50mg

Stable and Asymptomatic

• If mild or no symptoms and pulse only mildly elevated (<110bpm) ok to manage with PO meds
• Less reactive to PO medication than atrial fibrillation
• Cardioversion is preferred and treats 96-97% of atrial flutter

Stable and Symptomatic

• Goal <110bpm
  • Make sure you are not slowing down a normal physiologic response (e.g. fever, hypoxia, etc)
  • RACE-II trial demonstrated that lenient control (goal HR < 110bpm) was noninferior to strict control (HR < 80 bpm) in preventing the primary outcome

Cardioversion

• Consider for:
  • Symptoms <48hr
  • New diagnosis
  • No history of similar episodes
  • No LV dysfunction
  • No mitral valve disease
  • No prior thromboembolic event
  • Already Anticoagulated
• If cardioversion is considered, pretreatment with rate or rhythm control medications can reduce effectiveness
  • 90% effective, 60% effective with pretreatment

Anticoagulation Prior to Cardioversion

• Anticoagulation with Heparin or LMWH should be considered before cardioversion if time permits, otherwise immediately after cardioversion. (unless you are sure it has been <48 hours since onset of afib)

• Generally cardioversion while anti-coagulated is believed to be safe with a 1.3% risk of thromboembolism if on aspirin or other anticoagulant However the risk may be as great as 2% risk after 48 hours and preference should be given to anticoagulation prior to cardioversion in longer cases

Evidence of preexcitation

• Avoid AV nodal agents
• Unstable:
  • Unsynchronized cardioversion (200J)
  • Procainamide (if cardioversion unsuccessful)
    • 20-50mg/min until arrhythmia is controlled, hypotension occurs, QRS complex widens by 50% of original width, or total of 17mg/kg is given; followed by continuous infusion of 1-4mg/min
• Stable:
  • Try to avoid cardioversion without adequate anticoagulation

See Also

Atrial fibrillation

References

Authors

Colin Hoff, Kevin Lu, Ross Donaldson, Daniel Eggeman, Claire, Neil Young, Daniel Ostermayer