The development of catheter ablation techniques during the last decade provided new data about the mechanism of @entity4710 and at the same time, set new requirements for their classification. An accurate diagnosis of individual SVT can usually be made during an electrophysiologic study that precedes catheter ablation. Nevertheless, clinically acceptable differential diagnosis of SVT can be based on analysis of a standard 12-lead electrocardiogram. This may prove useful especially when selecting optimum antiarrhythmic drug according to a suspected mechanism of @entity943 . At the same time, electrocardiogram during SVT serves as a recording of clinical @entity943 for catheter ablation. At present, SVTs are divided into 3 main categories: 1. @entity4710 confined solely to atrial tissue, 2. @entity591 involving the AV junction, and 3. AV reentrant @entity591 involving one or more accessory connections with an electric impulse travelling between atria and ventricles. The first category can be further subdivided into: a) macroreentrant @entity591 related to the presence of macroscopic anatomical or functional barriers; b) focal @entity591 arising from a focus of abnormal automaticity or microreentry in the atrium; c) the @entity7129 resulting most probably from hypersensitivity to adrenergic stimulation; d) @entity955 based on the existence of multiple wandering wavelets in the atria. Electrocardiographic differential diagnosis is predominantly based on an analysis of the standard 12-lead ECG. Principal diagnostic features include the presence and timing of the P waves in relation to the QRS complex. Additional criteria comprise the presence or absence of @entity713 during the @entity591 , an @entity2270 orientation of the P waves and their morphology, the appearance of QRS alternans or frequency of @entity591 .

[ECG in the diagnosis of XXXX ].

@entity713 :: ('MESH:D054537', 'Disease') :: ['AV block'] @entity591 :: ('MESH:D013610', 'Disease') :: ['atrial tachycardias', 'tachycardia', 'tachycardias'] @entity955 :: ('MESH:D001281', 'Disease') :: ['atrial fibrillation'] @entity2270 :: ('MESH:C566610', 'Disease') :: ['axis'] @entity4710 :: ('MESH:D013617', 'Disease') :: ['supraventricular tachyarrhythmias', 'atrial tachyarrhythmias'] @entity943 :: ('MESH:D001145', 'Disease') :: ['arrhythmia'] @entity7129 :: ('MESH:D013616', 'Disease') :: ['syndrome of inappropriate sinus tachycardia']
@entity4710 :: (MESH:D013617,Disease) :: ['supraventricular tachyarrhythmias']
