<unk> <unk>  is a type of abnormal fast heart rhythm. It is a type of supraventricular<unk>  (SVT), meaning that it originates from a location within the heart above the bundle of His.<unk>  is the most common regular supraventricular<unk> . It is more common in women than men (approximately 75% of cases occur in females). The main symptom is palpitations. Treatment may be with specific physical maneuvers, medications, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.<unk>  occurs when a<unk>  circuit forms within or just next to the atrioventricular node. The circuit usually involves two anatomical pathways: the fast pathway and the slow pathway, which are both in the right atrium. The slow pathway (which is usually targeted for ablation) is located inferior and slightly posterior to the<unk>  node, often following the anterior margin of the coronary sinus. The fast pathway is usually located just superior and posterior to the<unk>  node. These pathways are formed from tissue that behaves very much like the<unk>  node, and some authors regard them as part of the<unk>  node. The fast and slow pathways should not be confused with the accessory pathways that give rise to Wolff-Parkinson-White syndrome (WPW syndrome) or atrioventricular reciprocating<unk>  <unk> . In<unk> , the fast and slow pathways are located within the right atrium close to or within the<unk>  node and exhibit electrophysiologic properties similar to<unk><unk>  tissue. Accessory pathways that give rise to WPW syndrome and<unk>  are located in the atrioventricular valvular rings. They provide a direct connection between the atria and ventricles, and have electrophysiologic properties similar to muscular heart tissue of the heart's ventricles.
AV nodal reentrant tachycardia
Tachycardia
Re-entry ventricular arrhythmia
Junctional ectopic tachycardia
Atrioventricular reentrant tachycardia
Wandering atrial pacemaker
Pre-excitation syndrome
Ventricular escape beat