Background Although
radiofrequency catheter ablation is the current state-of-the-art treatment for
ventricular tachyarrhythmias, it has limited success for several reasons, including insufficient lesion depth, prolonged
inflammation with subsequent recurrence, and
thromboembolisms due to myoendocardial thermal injury. Because
shock waves can be applied to deep lesions without heat, we have been developing a
shock-wave
catheter ablation ( SWCA ) system to overcome these fundamental limitations of
radiofrequency catheter ablation. In this study, we evaluated the efficacy and safety of our SWCA system for clinical application to treat
ventricular tachyarrhythmia. Methods and Results In 33 pigs, we examined SWCA in vivo for the following 4 protocols. First, in an epicardial substrate model (n=8), endocardial SWCA significantly decreased the sensing threshold (pre- versus postablation: 11.4±3.8 versus 6.8±3.6 mV ; P<0.05) and increased the pacing threshold (pre- versus postablation: 1.6±0.8 versus 2.0±1.1 V; P<0.05), whereas endocardial
radiofrequency catheter ablation failed to do so. Second, in a
myocardial infarction model (n=3), epicardial SWCA of the border zone of the infarcted lesion was as effective as ablation of the normal myocardium. Third, in a coronary artery application model (n=10), direct application of
shock waves to the epicardial coronary arteries caused no adverse effects in either the acute or chronic phase. Fourth, with an epicardial approach (n=8), we found that 90 shots per site provided an ideal therapeutic condition to create deep lesions with less superficial damage. Conclusions These results indicate that our new SWCA system is effective and safe for treatment of
ventricular tachyarrhythmias with deep arrhythmogenic substrates.