Search results
Results From The WOW.Com Content Network
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 ...
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.
Anatomically defined re-entry has a fixed anatomic pathway. Anomalous conduction via accessory pathways (APs) creates the re-entry circuit (which are also called bypass tracts), that exists between the atria and ventricles. Wolff–Parkinson–White syndrome (WPW) is an example of anatomically defined re-entry.
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.
AV reentrant tachycardia (AVRT) requires an accessory pathway for its maintenance. AVRT may involve orthodromic conduction (where the impulse travels down the AV node to the ventricles and back up to the atria through the accessory pathway) or antidromic conduction (which the impulse travels down the accessory pathway and back up to the atria ...
Atrioventricular nodal re-entry tachycardia, [11] which is caused by a dual AV node physiology and AVNRT can only occur in people with it, however almost half of the population have it, though only a few of them will develop AVNRT at some point in life.