低能量放电下标测无室性早搏的流出道室性心动过速

Objective This study reported initial experience of a new mapping method for ablation of syncope-caused ventricular tachycardia (VT) without combining frequent premature ventricular contraction (PVC). Methods All 11 recruited patients were female, mean age (39. 9 ± 13.7)years. They had experienced at least 1 syncope episode and were refractory to 2 or more antiarryhthmic agents in the past 1 to 3 years. Results ( 1 ) Clinical arrhythmia characteristics: In 5 patients, PVC or VT was induced by programmed stimuli without intravenous isoproterenol in right ventricular outflow tract(RVOT). In these patients, Holter monitoring recorded more PVCs ( mean 3678 beats/24 hours) with ventricular bigeminy or trigeminy, but less VT (mean 5. 8 episodes/24 hours). These patients suffered more transient amaurosis than syncope except one older woman combining hypertension. While in other 6 patients, VT could not be induced with programmed stimuli unless isoproterenol was administrated. These patients all suffered syncope in their medical history, their Holter monitoring recorded more VT (mean 15.5 episodes/24 hours)less PVC (mean 1208 beats/24 hours )with few ventricular bigeminy or trigeminy. (2) Electrophysiologic mapping and catheter ablation: Induced PVC or VT were frozen on monitor screen as reference, ablation catheter was posited on expected area of RVOT, pace mapping was performed firstly and Low Radio Frequency(LRF) energy( 15 ～20 W)was delivered at sites that paced VT morphology identical to reference VT in all 12 leads of ECG. Once the sites was found that VT morphology induced by LRF was identical to reference VT in all 12 leads of ECG,the radiofrequency energy would be increased to 35 ～50 W(50 ～55℃ )on same site until VT was eliminated. Then enlarge ablation area to about 1 cm2 around this site. All 11 patients were induced identical VT during low radiofrequency energy. ( 3 ) No VT/PVC was induced through program stimuli or intravenous isoproterenol repeatedly after ablation was considered as successful end point. Ten patients reached the end of ablation in the procedure ,9 targets located at sepal or posterior wall in RVOT, 1 did base of right coronary cusp. The only failure one also could be induced frequent matched VT by LRF, activating mapping found the earliest activated site located in inferior of left coronary cusp. However,PVC couldn't be eliminated,which suggested the target may locate at the pericardial layer.(4)No syncope or amaurosis was observed in 3 ～ 14 months of follow-up. Conclusions Low energy stimuli mapping can be used as a new mapping method as well as active mapping, pace mapping and spike potential mapping, especially to those patients suffer from repeat syncope or amaurosis induced by VT without combining frequent premature ventricular contraction.

Low energy stimuli mapping for ablation of ventricular tachycardia originating from the right ventricular outflow tract