Ablation of Superior Slow Pathway in Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia
The usual arrhythmogenic substrate of atrioventricular nodal reentrant tachycardia (AVNRT) is a slow pathway (SP) that can be ablated in the posterior or mid septum. We have proposed a rare, superior (sup-) type of fast-slow (F/S-) AVNRT incorporating a s
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24
Yoshiaki Kaneko
Keywords
Superior slow pathway • Atrioventricular nodal reentrant tachycardia • Ablation Electrophysiology
24.1 Introduction
“anterior superior SP” in his textbook, which can be successfully ablated in the noncoronary aortic cusp of Valsalva Slow pathway (SP) ablation is a highly successful, curative (NCC), but did not display any electrophysiological data [10]. therapy for atrioventricular (AV) nodal reentrant tachycardia In an anatomical and electrophysiological study using a (NRT), although some cases are refractory to the posterior canine preparation, Racker et al. reported the presence of an delivery of therapy, behind the compact AV node [1–4]. The AV junctional pathway that originates posterior to the comparticipation of a variant of the SP in the reentry circuit, pact node and extends superiorly, i.e., superior atrionodal behind the area that is usually treated, has been proposed as bundle [14, 15]. A recent anatomical and biochemical study a cause of difficult ablation of AVNRT [5–12]. In patients of the specialized conduction system using a rat preparation presenting with atypical, fast-slow AVNRT, we recently demonstrated AV node-like tissue adjacent to the NCC, just reported a new type of SP located superiorly at the apex of above the central fibrous body, identified as the retroaortic Koch’s triangle, serving as the retrograde limb of the reentry node, but the presence of AV node-like tissue connecting the circuit, which we ablated successfully near the His bundle compact AV node and retroaortic node has not been con(HB) [7]. We named the tachycardia a superior type of fast- firmed [16, 17]. Recently, Inoue, the first author to describe slow AVNRT (sup-F/S-AVNRT). In this chapter, we review the presence of rightward inferior extension, confirmed the the diagnosis and ablation therapy of this unique AVNRT. presence of AV nodal tissue originating superiorly from the compact AV node, i.e., superior extension, in a pathological analysis of human hearts (unpublished).
24.2 History of Superior SP Although the anatomic existence of a superior SP has never been confirmed in humans [13], several investigators have hypothesized its presence. Keim et al. first observed a single case of typical AVNRT in which the SP was identified anterior to the fast pathway (FP) by intraoperative ice mapping [8]. Nawata et al. reported three cases of atypical AVNRT in which the presence of the superior SP was hypothesized during an electrophysiologic study, but did not proceed with its ablation [12]. Jackman et al. referred to the presence of an Y. Kaneko Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan e-mail: [email protected]
24.3 Diagnosis of sup-F/S-AVNRT In principle, the electrophysiological diagnosis of sup-F/SAVNRT was based on (1) confirmation of the presence of superior SP, (2) long RP tachycardia with the earliest site of atrial activation at the HB region, and (3) exclusion of atrial tachycardia (
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