Junctional escape rhythm
Paroxysmal Supraventricular tachycardia
· SVT often used synonymously with AV nodal reentry tachycardia (AVNRT), can be used to refer to any tachydysrhythmia arising from above the level of the Bundle of His.
· Paroxysmal SVT (PSVT) describes an SVT with an abrupt onset and offset — characteristically seen with reentrant tachycardias involving the AV node such as AVNRT or atrioventricular reentry tachycardia (AVRT)
· AVNRT (commonest cause) is typically paroxysmal and may occur spontaneously or upon provocation with exertion, caffeine, alcohol, beta-agonists (salbutamol), or sympathomimetics
· It is more common in women than men (~ 75% of cases occurring in women)
and may occur in young and healthy patients as well as those suffering from chronic heart disease.
· General Features of AVNRT
Regular tachycardia ~140-280 bpm.
QRS complexes are usually narrow (< 120 ms) unless pre-existing bundle branch block, accessory pathway, or rate-related aberrant conduction.
ST-segment depression may be seen with or without underlying coronary artery disease.
P waves may be buried in the QRS complex, visible after the QRS complex, or very rarely visible before the QRS complex.