Atrial tachycardia

Background

  • Also known as focal atrial tachycardia, Paroxysmal Atrial Tachycardia (PAT), unifocal atrial tachycardia, ectopic atrial tachycardia
  • Rate >100 bpm
  • Electrical focus that originates outside in the sinus node at a single location
    • By comparison, reentrant tachycardias (eg. AVRT, AVNRT) involve multiple foci/ larger circuits
  • Sustained atrial tachycardia can lead to a tachycardia-induced cardiomyopathy.
  • Differs from sinus tachycardia in that the impulses are generated by an ectopic focus somewhere within the atrial myocardium rather than the sinus node.
  • Multifocal atrial tachycardia is similar, but has P waves with at least three different morphologies.
  • The combination of atrial tachycardia plus AV block is particularly common in digoxin toxicity.

Clinical Features

  • Often asymptomatic
  • Palpitations
    • Non-specific finding
    • Associated with all tachydysrhythmias, not just AT
    • Rapid fluttering/throbbing/pounding sensation in the chest or neck
  • Syncope
    • Patients with AT rarely present with syncope
    • Cerebral hypoperfusion is more common with a ventricular rate >200 bpm
  • Chest pain
    • Can present if there is underlying cardiovascular disease
    • Represents a worsening of the associated disease
  • Dyspnea
    • Can present if there is underlying cardiovascular disease
    • Represents a worsening of the associated disease

Differential Diagnosis

Narrow-complex tachycardia

Evaluation

Workup

  • ECG

ECG Features

  • Atrial rate >100 bpm
  • P-waves
    • Morphology abnormal (when compared with sinus P wave due to ectopic origin)
    • Has at least three consecutive identical ectopic p waves
    • Axis frequently abnormal (e.g. inverted in inferior leads)
  • QRS complexes
    • Usually normal morphology (unless pre-existing bundle branch block, accessory pathway, or rate related aberrant conduction)
  • Baseline isoelectric (unlike atrial flutter)
  • AV block may be present

Management

Unstable

  • Cardioversion

Stable

Initial treatment may be aimed at rate control, while later resolution of clinical symptoms usually requires restoration of normal sinus rhythm.

See Also

References

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