title: Development of a novel shock wave catheter ablation system--the first feasibility study in pigs.
abstract: BACKGROUND
  Radio-frequency catheter ablation (RFCA) using Joule heat has two fundamental weaknesses: the limited depth of treatment and the risk of thrombus formation. In contrast, focused shock wave (SW) therapy could damage tissues at arbitrary depths without heat generation. Thus, we aimed to develop a SW catheter ablation (SWCA) system that could compensate for the weaknesses of RFCA therapy.
  
  
  RESULTS
  We developed a SWCA system where the SW generated by a Q-switched Holmium: yttrium aluminum garnet (YAG) laser beam was reflected by a reflector attached to 14-Fr catheter tip and then was converged onto the focus. We examined the feasibility of our system on pigs in vivo. When applied using the epicardial approach, the SWCA caused persistent spheroidal lesions with mild superficial injury than the RFCA. The lesions were created to a depth based on the focal length (2.0 mm) [2.36 ± 0.45 (SD) mm immediately after procedure, n = 16]. When applied to the atrioventricular (AV) node using the endocardial approach, the SWCA caused junctional escape rhythms in 2 pigs and AV block in 12 pigs (complete AV block in 9) in acute phase (n = 14). Nine of the 14 pigs survived with pacemakers for the long-term study, and the AV block persisted for 12.6 ± 3.9 (SD) days in all surviving pigs. Histological examination showed AV nodal cell body atrophy in the acute phase and fibrotic lesions in the chronic phase. Importantly, no acute or chronic fatal complications were noted.
  
  
  CONCLUSIONS
  Our novel SWCA system could be a promising modality as a non-thermal ablation method to compensate for the weaknesses of RFCA therapy. However, further research and development will be necessary as the current prototype still exhibited the presence of micro-thrombus formation in the animal studies.
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Yuhi
authors: Y
authors: Hasebe
authors: Department of Advanced Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Hiroaki
authors: H
authors: Yamamoto
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Koji
authors: K
authors: Fukuda
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Kensuke
authors: K
authors: Nishimiya
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Kenichiro
authors: K
authors: Hanawa
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Tomohiko
authors: T
authors: Shindo
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Masateru
authors: M
authors: Kondo
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Makoto
authors: M
authors: Nakano
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Yuji
authors: Y
authors: Wakayama
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Kazuyoshi
authors: K
authors: Takayama
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Advanced Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Hiroaki
authors: H
authors: Shimokawa
mesh_terms: D000818:Animals; D001283:Atrioventricular Node / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D004699:Endocardium / Q000601:surgery*; D005240:Feasibility Studies; D008297:Male; D013552:Swine
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