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During AVRT, the electrical signal passes in the normal manner from the AV node into the ventricles. Then, the electrical impulse pathologically passes back into the atria via the accessory pathway, causing atrial contraction, and returns to the AV node to complete the reentrant circuit (see figure). Once initiated, the cycle may continue ...
The majority of time symptomatic WPW fits the definition of AVRT (Supraventricular tachycardia) however AVNRT (dual AV nodal physiology) exist in ~10% of patients with WPW syndrome creating the possibility of spontaneous atrial fibrillation degenerating into ventricular fibrillation (VF). The fact that WPW patients are young and do not have ...
During typical AVNRT, electrical impulses travel down the slow pathway of the AV node and back up the fast pathway. The fundamental mechanism of AVNRT is a presence of a dual atrioventricular node physiology (present in half of the population), which acts as a re-entrant circuit within the atrioventricular node. [4] This can take several forms.
This type of reentry is known as an anatomical reentrant circuit, because the accessory pathway is a fixed anatomically defined pathway. Another type of reentrant circuit, though, is atrioventricular nodal reentrant tachycardia, or AVNRT.
AV nodal reentrant tachycardia is often curable by ablating one of the pathways in the AV node (usually the slow pathway). Atrial fibrillation can also be treated, by performing a pulmonary vein isolation, but the results are less reliable.
In other cases, the extra pathway can set up a reentry circuit. In the case of a reentry circuit, the signal might move back up the accessory pathway, since the majority of these Bundles of Kent are actually bidirectional, meaning the signal can go from atrium to ventricle as well as from ventricle to atrium.
The underlying anatomical causes of PSVT, specifically atrioventricular nodal reentry, involve the presence of two functionally distinct conduction pathways within the AV node and the formation of a reentrant circuit that sustains the tachycardia. [8] These pathways within the AV node are known as the fast pathway and the slow pathway. [9]
It is a supraventricular tachycardia, and a cause of atrioventricular reentrant tachycardia (AVRT). PJRT can cause chronic tachycardia that, untreated, leads to cardiomyopathy. The cause is an accessory pathway in the heart which conducts from the ventricles back to the atria.