Electrophysiological manifestations of rare supra-ventricular tachycardias with concealed nodo-ventricular fibers
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Electrophysiological manifestations of rare supra-ventricular tachycardias with concealed nodo-ventricular fibers Wei Wei 1 & Caihua Sang 2 & Sulin Zheng 3 & Roderick Tung 1,4 & Xunzhang Wang 1,5 & Yumei Xue 1 & Yuanhong Liang 1 & Shangming Song 6 & Tongbao Liu 6 & Deyong Long 2 & Yang Liu 1 & Jianzeng Dong 2 & Changsheng Ma 2 & Shulin Wu 1 Received: 20 May 2020 / Accepted: 3 August 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Purpose To clarify the electrophysiological mechanism of supra-ventricular tachycardias (SVT) with concealed nodo-ventricular (NV) fibers. Methods We studied the intra-cardiac electrograms during electrophysiological study (EPS) of three cases of SVT which concerned concealed NV fibers. Electrophysiological maneuvers including right ventricular apex entrainments, RS2 stimuli, adenosine triphosphate injection and so on were done for differential diagnosis before ablation. Results Among these patients, one had atrio-ventricular nodal reentrant tachycardia (AVNRT) with a bystander NV fiber; the other 2 had NV fiber mediated orthodromic reentrant tachycardias (NVRT). VA dissociation was observed during SVT in all 3 cases with an antegrade His bundle conduction sequence. Ventricular stimulation at His refractory period reset the H-H intervals and the V-V intervals sequentially, suggesting the existence of a retrogradely conductive accessory pathway. Adenosine injection could terminate these tachycardias. The cycle length of an NVRT prolonged during the status of functional right bundle branch block, suggesting that the fiber located on the right side. Multiple QRS fusion morphologies during ventricular entrainments or ventricular stimulation at His refractory period at a fixed position could be observed in these cases. Conclusions Concealed NV fibers can either mediate orthodromic reentrant tachycardia or be a bystander of AVNRT. V-A dissociation usually occur during such SVTs. Dissociation of H and V due to entrainment of right ventricular apex is a newly discovered maneuver to differentiate AVNRT from NVRT. Keywords Nodo-ventricular fiber . Electrophysiological mechanism . Differential diagnosis . Ablation
1 Introduction Nodo-ventricular (NV) fiber is a rare type of Mahaim’s bundle which connects the atrio-ventricular (AV) node and the ventricular myocardium. In the light of low prevalence of Mahaim’s bundle (< 3%) [1], occurrence of NV
fibers is even rare. Previous literatures about NV fibers were mainly case reports and not all of them were describe clearly. We met with 3 cases of NV fibers from 3 hospitals. We will clarify the electrophysiological mechanisms of these NV fibers by analyzing their similarities and individual characteristics.
Wei Wei, Caihua Sang and Sulin Zheng contributed equally to this work. * Changsheng Ma [email protected]
3
The First People’s Hospital of Shunde, Shunde Hospital of Southern Medical University, Foshan, Guangdong Province, People’s Republic of China
4
The University of Chicago Medicine, Center for Arrhythmia Ca
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