Introduction
Paroxysmal supraventricular tachycardia (PSVT) refers to cardiac
arrhythmias originating above the ventricle that results in sudden rapid
heart rate episodes. More than 90% of PSVTs are atrioventricular nodal
reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia
(AVRT) or Wolff-Parkinson-White (WPW) syndrome, which are caused by
abnormal electrical extra pathways in heart, including slow pathways
(SP) or accessory pathways (AP).1 Catheter-based
radiofrequency ablation (RFA) of these extra pathways is highly
effective for the treatment of PSVTs. The procedure is often successful,
but sometimes it becomes complicated when accurate localization of SP or
AP is difficult.2 Location of the ablation target is
determined based on anatomical markers and electrical potentials, and
obtaining adequate electrograms at ablation sites is important for
effective ablation of PSVTs.2, 3
Mapping resolution of the ablation catheter is dependent on electrode
size and spacing. A novel ablation catheter (IntellaTip MiFi OI, Boston
Scientific, Boston, MA, USA) has three additional, radially-distributed
mini electrodes (MEs) located 1.3 mm from the distal tip that offer
high-resolution electrograms close to ablation sites. The ME-equipped
ablation catheter provides more precise localization of the actual
ablation site. It has been shown to be helpful to avoid unnecessary
radiofrequency application for cavotricuspid isthmus ablation in
previous clinical studies.4, 5 The ME signals
visualized in ablation catheter can be advantageous for accurate
localization of SP or AP and identification of discrete pathway
electrograms during RFA for PSVTs. This study aimed to evaluate the
mapping performance and efficacy of novel ablation catheters equipped
with MEs compared to conventional ablation catheters, in RFA for AVNRT
or AVRT/WPW syndromes.