Shortcut Link Between the Fast and Slow Pathways and the Mechanism of Cure in Atrioventricular Nodal Reentrant Tachycardia by Catheter Ablation

Abstract

In patients with a shortcut link between the fast and slow pathways, slow pathway conduction itself does not need to be impaired to eliminate the AVNRT, whereas in patients without this shortcut link, slow pathway conduction must be impaired.

Orthodromic capture by atrial scan pacing for a narrow QRS tachycardia with ventriculoatrial block: What is the mechanism?

“…reported that observation of orthodromic capture of the atrial electrogram at the atrial EAS by CS pacing could rule out the presence of a UCP in AVNRT 3 . Another explanation of VAB during AVNRT is a shortcut link connecting the dual nodal pathways, reported by Nogami et al 4 . In the presence of a shortcut link, we could explain the mechanism of the VAB during the tachycardia as follows (Figure 2).…”

“…This ruled out atrial tachycardia and orthodromic atrioventricular reentrant tachycardia (ORT) using rule out the presence of a UCP in AVNRT. 3 Another explanation of VAB during AVNRT is a shortcut link connecting the dual nodal pathways, reported by Nogami et al 4 In the presence of a shortcut link, we could explain the mechanism of the VAB during the tachycardia as follows (Figure 2). The AVNRT had dual loop circuits, one circuit contained the atrial myocardium and in the other circuit, the antegrade slow pathway and retrograde slow pathway were connected by a shortcut link.…”

Analysis of Electrophysiological Activity in Koch's Triangle Relevant to Ahlation of the Slow AV Nodal Pathway

“…Following curative surgical treatment,^'^ catheter ablation for AV nodal reentrant tachycardia was introduced in 1986 using DC shocks applied to the retrograde fast pathway, a few millimeters from the His hunjjlg 24.2.5 purther attempts to consistently ablate the "guilty" retrograde fast pathway without modifying anterograde conduction have been unsuccessful so that the risk of AV block targeting the fast pathway remains about 3% with the use of radiofrequency (RF) current.^'*"^'^ This risk is greater than using RF ahlation to target the "slow pathway" (SP) in which energy is applied 10-20 mm posterior to the His bundle with an incidence =1% of AV hlock. This approach Introduced by Jackman et al^° has become the therapeutic procedure of choice.^""""^^ Although ablation for AVJRT is dichotomized into fast or slow pathway ablation, there are arguments suggesting disruption of the link between botb pathways (or of an "intermediate" pathway) as the mechanism of ,U^,g 46,48,49 Different approaches to target the slow pathway have heen described. In the electrophysiological approach, electrogram patterns are nsed to identify the ablation site^"*^^ whereas in the anatomical approach, the ablation site is mainly selected on the basis of anatomical criteria (in combination with an atrial/ventricular electrogram ratio of 0.5 or less).…”