Atrial Tachycardia

Atrial tachycardia is technically a supraventricular tachycardia.  It most commonly originates from an ectopic atrial focus (there is usually a single focus but rarely can multiple foci be responsible).

Background

  • Not uncommon- accounts for around 5-10% of the supraventricular tachycardias
    • Often an incidental finding in elderly patients
  • Often it is paroxysmal (i.e. episodic)
  • A relatively common area for ectopic electrical activity is just at the entrance to the pulmonary vein
    • Occasionally this can be treated with ablation (if necessary)

Causes

  • May be idiopathic but is classically seen in
    • Digoxin toxicity
    • Congenital Heart disease
    • Other structural heart abnormalities (including ischaemic change and valvular disease)

ECG

  • Atrial rate >100bpm
  • Because atrial depolarisation is not occurring from the SA node, P waves may be abnormal (e.g. inverted, often in the inferior leads II, III and aVF)
    • NB these can appear almost identical to atrial ectopic beats but they are not isolated (>3 consecutively)
  • Normal (narrow) QRS complexes (unless there is another underlying condition affecting the QRS)
    • Each is preceded by a P wave
    • QRS complexes may be absent with some P waves due to an associated AV block which is common
  • In contrast to atrial fibrillation and atrial flutter, there is an obvious isoelectric baseline

Presentation

  • Sudden onset palpitations and associated symptoms e.g. light-headedness/dizziness; dyspnoea; chest pressure; fatigue etc

Management

  • If the patient presents acutely, manage as adult tachycardia (ABCDE) approach (see here)
  • Beta-blockade e.g. with propanolol, or cardioselective calcium channel blocker e.g verapamil is usually first line
  • Cardioversion may be required is the tachycardia is refractive to pharmacological treatment
  • Occasionally, adenosine can also be used to slow the heart rate
  • For patients with persistent/recurrent problems from AT, catheter ablation of the ectopic focus is also an option
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