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Atrial Flutter

Atrial Flutter

Pathophysiology

  • 2nd MC pathologic arrhythmia behind AFib
  • Results from a re-entrant circuit located within the Right Atrium (tricuspid valve)
  • Continuous circuit of impulses is created
    • Rate: Rapid Atrial Contraction (250-350BPM)
    • Organized re-entry, repetitive and regular rhythm, Atrial rate of 300bpm
    • Normal AV nodal conduction, thus ventricular rate normal of 150 bpm

Characteristics

  • Commonly occurs in patients with COPD, HD, CAD, Post-Op heart surgery
  • May occur in structurally normal heart
  • Often converts spontaneously to atrial fibrillation or sinus rhythm
  • If 3:1 block, consider medications or advanced AV disease

Major Categories

1) Typical (Type I) Flutter: Cavotricuspid Isthmus (CVI) Dependent

  • Counterclockwise Reentry
    • 90% of atrial flutters
    • Forms in the RA, interatrial conduction occurs first via the coronary sinus os, and later Bachmann's Bundle; retrograde LA conduction
    • Inverted flutter waves inferiorly
    • Positive flutter waves in V1 simulating P waves
  • Clockwise Reentry
    • Forms in the RA, interatrial conduction occurs first via Bachmann's Bundle, then later via the coronary sinus os; anterograde LA conduction
    • Positive flutter waves inferiorly (II, III, and AVF)
    • Broad, inverted flutter waves in V1
  • Circuit is around the tricuspid annulus
    • Limited by the SVC, IVC, Coronary Sinus, Crista Terminalis
  • Normal and abnormal hearts
    • Characteristic atrial rate of 300 bpm commonly with 2:1 AV block
    • Right atrial reentry parallel to tricuspid annulus and dependent on conduction through the isthmus between IVC and tricuspid annulus
    • Can be Counterclockwise and clockwise
    • Macroscopic circuit in the RA and direction of propagation is usually counterclockwise around the CVI
    • Around the tricuspid annulus (RA) is most common
    • Negative sawtooth flutter waves in II, III, and AVF
    • May be clockwise, still CVI

2) Atypical Flutters

  • Upper Loop Reentry (Upper RA)
  • Septal/Anteroseptal Reentry (Septal RA)
  • Lower Loop Reentry (Lower RA)

ECG Findings

  • Sawtooth or flutter waves at regular intervals
  • May see clockwise, still CVI
    • Negative sawtooth flutter waves in II, III, and AVF
    • May be clockwise, still CVI
    • Negative p waves in V1, upright in the inferior leads

Treatment

  • Acute Conversion
    • IV Ibutilide (Corvert): Most effective for acute conversion
    • Procainamide: 2nd line
    • Sotalol
  • Rate Control
    • Beta-blockers or CCBs
    • AV nodal blocking agents
  • Chronic Management
    • Antiarrhythmic drugs (Class I or III)
    • Radiofrequency Ablation: Definitive treatment, high success rate for typical flutter
    • Anticoagulation based on CHA₂DS₂-VASc score