Efficacy ahd safety of catheter electrical ablation for ventricular tachycardia Experimental and clinical studies.

We studied the factors determining the extent of myocardial damage induced by catheter electrical ablation in 23 mongrel dogs and evaluated the efficacy and safety of catheter electrical abation in 6 patients with medically refractory ventricular tachycardias (VT). Electrical shocks were delivered on the epicardium (EPI) and endocardium (END) of the ventricular wall of open-chest anesthetized dogs through a 6F USCI electrode catheter. Effect of the extent of electrode contact pressure was examined by the presence or absence of monophasic action potential using the contact electrode technique. The former was defined as the hard touch condition and the latter was defined as the soft touch condition. The myocardial lesion induced by EPI fulguration was larger than that by END fulguration (EPI-100 J soft touch: 10.2±2.9mm in diameter. 6.6±1.6mm in depth vs END-100 J soft touch: 7.7±1.7mm in diameter, 5.0±1.2 mm in depth; p<0.05, p<0.05). The lesion diameter and lesion depth were enlarged by increasing the amount of delivered energy. The lesion depth by the hard touch condition was significantly greater than that by the soft touch condition. The transmural perforation was observed in all EPI fulguration in the hard touch condition of the right ventricular wall. In the clinical study, one to three shocks (mean 1.8±0.7) of 60 to 200 J (maen 151±48 J) were delivered per session in 6 patiens with medically refractory VT. Two of the 6 patients had no recurrence of VT even without antiarrhythmic therapy and the remaining 4 patients had no recurrence with the same regimen that was ineffective before ablation during a follow-up period of 11.3±2.3 (range 8 to 14) months. The perforation of the right ventricular wall occurred immediately after ablation in one patient whose shock was delivered in the hard touch condition, but the patient had a good clinical outcome. In conclusion, catheter ablation for VT was effective and safe when it was performed in the soft touch condition.