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Atrial tachycardia is a supraventricular tachycardia (SVT) that does not require the atrioventricular (AV) junction, accessory pathways, or ventricular tissue for its initiation and maintenance. It occurs in persons with normal hearts and in those with structurally abnormal hearts, including individuals with congenital heart disease (particularly after surgery for repair or correction of congenital or valvular heart disease).
Manifestations of atrial tachycardia include the following:
- Rapid pulse rate: In most atrial tachycardias, the rapid pulse is regular; it may be irregular in rapid atrial tachycardias with variable AV conduction and in multifocal atrial tachycardia (MAT)
- Episodic or paroxysmal occurrence
- Sudden onset of Palpitations
- Continuous, sustained, or repetitive tachycardia: If atrial tachycardia is due to enhanced automaticity
- Warm-up phenomenon: Tachycardia gradually speeds up soon after onset (may be clinically inapparent)
- Dyspnea, dizziness, lightheadedness, fatigue, or chest pressure: In tachycardic episodes accompanied by palpitations
- Syncope: With rapid rate and severe hypotension
- Heart-failure symptoms and reduced effort tolerance: Early manifestations of tachycardia-induced cardiomyopathy in patients with frequent or incessant tachycardia
Reentrant atrial tachycardia is not uncommon in patients with a history of a surgically repaired atrial septal defect. The scar tissue in the atrium may give rise to the formation of a reentrant circuit.
On physical examination, the primary abnormal finding is a rapid pulse rate. The rate is usually regular, but it may be irregular in rapid atrial tachycardias with variable AV conduction and in MAT. Blood pressure may be low in patients presenting with fatigue, lightheadedness, or presyncope.
The primary treatment during a bout of atrial tachycardia is considered to be rate control using AV nodal blocking agents (eg, beta-blockers, calcium channel blockers). Antiarrhythmic drugs can prevent recurrences and may be required; a calcium channel blocker or beta-blocker also may be required in combination therapy. Specific antiarrhythmic therapies include the following:
- Atrial tachycardia from triggered activity: Verapamil, beta-blockers, and adenosine
- Atrial tachycardia from enhanced automaticity: Beta-blockers, but overall success rates are low
- Refractory recurrent atrial tachycardia: Class Ic antiarrhythmic drugs
- Maintenance of sinus rhythm: Class III antiarrhythmic drugs
- Cardioversion: For patients in whom the rhythm is not well-tolerated hemodynamically and/or in whom rate-control drugs are ineffective or contraindicated
- Radiofrequency catheter ablation: For symptomatic, medically refractory patients
- Surgical ablation: For patients with complex congenital heart disease
- Calcium channel blockers: Used as the first line of treatment
- Magnesium sulfate: When administered to correct hypokalemia, most patients convert to normal sinus rhythm (NSR)