AV Nodal Re-Entrant Tachycardia: Causes

Pathogenesis (development of disease)

AV nodal re-entrant tachycardia (AVRT; acceleration of heart rate to 160-250 beats per minute due to a short-circuit connection between the atria and ventricles bypassing the AV node/other physiologic pacemaker besides the sinoatrial node) can be further subdivided based on the presence of preexcitation syndrome (premature excitation of the ventricle via congenital conduction structures that parallel the AV node):

  • AVRT with preexcitation (Wolff-Parkinson-White syndrome; WPW syndrome): in which excitation is directed via a short-circuit conduction pathway (Kent bundle) instead of via the AV conduction pathway. Thus, permanent (“permanent”) or intermittent (“interrupting”) tachycardia (heart rate to > 100 beats per minute) occurs.
  • AVRT without preexcitation: in this case, there is either a genetic abnormality of the conduction system or it occurs in the context of mitral valve prolapse (malformation of the mitral valve apparatus). Circular excitations occur due to pathways conducting at different rates.