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
Notes on Medicine/Surgery 