Supraventricular arrhythmias encompass atrial premature beats, supraventricular tachycardias (SVTs), and atrial fibrillation. SVT is used to describe tachycardias in which the mechanism involves tissue from the His bundle or above, thus including atrial tachycardias, atrioventricular nodal reentrant tachycardia, and atrioventricular reentrant tachycardia due to accessory pathways. Atrial fibrillation is not included among the SVTs and is described elsewhere. The term tachycardia refers to atrial and/or ventricular rates greater than 100 beats per minute at rest. Atrial premature beats, the most common supraventricular arrhythmia, can be seen in Holter recordings in the majority of healthy individuals, and increase in frequency with age and presence of structural heart disease. Paroxysmal SVTs that can be terminated by vagal manoeuvres are usually reentrant tachycardias involving the atrioventricular node, such as atrioventricular nodal reentrant tachycardia or atrioventricular reentrant tachycardia. Symptoms may result in a poor quality of life. Rarely, patients with the Wolff–Parkinson–White syndrome develop atrial fibrillation that may degenerate into ventricular fibrillation in case the anterograde refractory period of the accessory pathway is very short and permanent forms of SVTs result in tachycardiomyopathy with left ventricular dysfunction. Paroxysmal SVT can be terminated by vagal manoeuvres, adenosine, overdrive pacing, and DC cardioversion. Atrial flutter, the most common atrial tachycardia, is a macro-reentrant atrial tachycardia that can be terminated by drugs, overdrive atrial pacing, and DC cardioversion. Most SVTs can be successfully treated by catheter ablation facilitated by modern electroanatomical mapping systems. Long-term antiarrhythmic drug therapy may be required for patients who are not suitable for or cured by catheter ablation.
Characteristics and Outcomes of Atrial Tachycardia Originating from the Sinus Venosus during Catheter Ablation of Atrial Fibrillation