It is a disease characterized by tachyarrhythmias (i.e. arrhythmias in which the heart beats faster than normal). Tachycardic attacks have different durations and can be accompanied by anxiety, sweating, hypotension, and a feeling of palpitations. These attacks appear and stop suddenly and during the attack the heart beats quickly and regularly... Sometimes they stop spontaneously, sometimes after specific maneuvers (such as the Valsalva maneuver, a forced expiration with a closed glottis), other times with the use of drugs. Treatment involves the use of antiarrhythmic drugs or transcatheter ablation (a percutaneous procedure that allows the definitive resolution of the problem in 99% of cases).

They are related to the presence of abnormal electrical structures (wires) inside the heart that can form abnormal electrical impulses or carry electrical impulses in an abnormal way. Usually these are areas with different conduction speeds that make the electrical impulse "spin", causing a short circuit and the abnormal contraction of the heart. The heart rate can vary between 150 and 250 beats per minute. The most common forms of supraventricular tachycardia (SVT) are:

Paroxysmal supraventricular nodal reentry tachycardia (AVNRT), in this benign pathology a normal structure of the heart's electrical system called the atrioventricular node presents a variant, called double nodal physiology (a double partition with two wires instead of one and different electrical characteristics) which can in certain situations generate a short circuit (tachycardia);

Paroxysmal atrioventricular reentry tachycardia through an accessory pathway (WPW-ART, Wolf-Parkinson-White syndrome), linked to the presence of an accessory bundle (extra electrical wire) that conducts the cardiac impulse through abnormal areas of the heart. This accessory pathway represents an additional path for the cardiac impulse, which is usually not present in the heart and can be a substrate, that is, the heart's "predisposition" to develop arrhythmias in certain situations. In fact, the impulse passes in an anomalous manner between the accessory pathway and the pathway that normally conducts the signal. There are various types of accessory pathways, that is, located in different points but above all with different speeds of conduction of the impulse. This means that there are "good" accessory pathways (which do not cause arrhythmias or which cause them but are not dangerous) and "bad" accessory pathways (which cause fast or life-threatening arrhythmias). Not all accessory pathways need to be treated.

The electrophysiologist, in relation to some parameters, almost always clinical, sometimes instead for work or competitive suitability, chooses the most appropriate therapy, medical or ablation or nothing. If the arrhythmia from an anomalous pathway must be treated, ablation is almost always indicated; in particular cases the therapy can be pharmacological. The presence of the Kent bundle can be diagnosed in the majority of patients even in the absence of symptoms with the execution of an ECG, other times (occult accessory pathways) it requires the execution of an intracavitary electrophysiological study or the analysis of an electrocardiogram (ECG) tracing during the arrhythmia, other times a cardiac Holter since the accessory pathway appears on the ECG intermittently during the day.