| Background: Radiofrequency catheter ablation has emerged as a first-line therapy for a host of arrhythmia diseases.As a novel ablation method,the safety and efficacy of high-power short-duration ablation has been constantly confirmed in the catheter ablation of atrial fibrillation.Due to its specific anatomical structure,coronary sinus and its branches play an significant role in the occurrence of rapidly atrial arrhythmia,atrioventricular node reentrant tachycardia,accessory-pathway-related tachycardia and idopathic ventricular arrhythmia.However,because of the rising impedance and high temperaturein,it is often difficult for the coronary sinus to be fully ablated with the conventional ablation method,and may result in failure of the operation and a sharp increase in the risk of complications.Whether high-power short-term ablation is also suitable for radiofrequency ablation in the coronary sinus is under dispute.Objective: Combining the experimental animal study and clinical cases,this study sought to investigate biophysical characteristics and safety features of high-power short-duration radiofrequency ablation in coronary sinus.Methods and Results:Part I Experimental study in vitro:Using Langerdorff-like perfusion system,the coronary sinus of fresh isolated porcine hearts perfused with blood was established to simulate the physiological circulation mode.A.Preliminary experiment: To determine the most appropriate parameters for ablation,which were defined as a minimum ablation parameter that can produce the stably visible thermal damages of the tissue with few side effects,several patterns were tested.The experimental sets of power were 35 watts,40 watts,45 watts,50 watts,55 watts,60 watts,65 watts for high-power short-duration in the coronary sinus,and application duration varied from 25 seconds to 90 seconds.Combined with the literature reports and experiences of our center,the conventional ablation pattern was confirmed.All the ablation applications were under the principle of similar AI and titration ablation.B.Experiment: The appropriate parameters for high-power short-duration group were 45w/5s,with the total duration of titration ablation of 25 seconds.The appropriate parameters for conventional group were 25w/10 s,with the total duration of titration ablation of 50 seconds.With the determined optimal parameters,the corresponding lesions were obtained by single ablation and titration ablation of high-power short-duration group and conventional group respectively,and sizes of those injuries were measured.C.Results:a.Single ablation: A total fifteen lesions were obtained by single ablation in the two groups: eight lesions were obtained by high power short-duration ablation(45w/5s),and seven lesions were obtained by single ablation in the conventional mode of 25w/10 s.The average length,width,and depth of high-power short-duration ablation lesions were(5.74±0.61?6.02±0.74?1.62±0.39)mm,and the average length,width,and depth of conventional ablation lesions were(5.10±0.92?4.79±1.24?2.28±0.70)mm.In the high power ablation group,the width of the lesion was increased and the depth was shallower(p=0.034,p=0.039,respectively).There was no significant difference in the lesion volume between the two groups(31.05 ±13.97 vs33.70 ±22.27,p=0.784).b.Titration ablation: Total twenty-eight lesions were made.There were sixteen lesions for high-power short-duration group,and twelve thermal damages were made in the conventional group.The average length,width,and depth of high-powershort-duration ablation lesions were(8.60 ± 1.40,9.40 ± 2.14,4.66 ± 1.13)mm,and the average length,width,and depth of conventional ablation lesions were(8.43+1.61?7.78±1.71?4.29±0.99)mm.There was no difference between the length and depth of lesions in the high-power group and the conventional ablation(p=0.765,p=0.375).However,the high-power ablation damages had a wider trend than the conventional ones(p=0.053).In terms of lesion volume,the volume of high-power group was larger than that of conventional pattern(205.47±84.79 vs 155.25±98.26,p=0.053).When it comes to the different parts in the coronary sinus,high-power short-duration ablation resulted in deeper(p=0.026)and larger lesions(p=0.028)in the middle cardiac vein.A increasing trend of the width of the lesion was also appeared(p=0.065).The total time of high-power short-duration ablation and the time of a single radiofrequency discharge were shortened.Serious complications,such as “steam pop”,were not developed during the applications of high-power short-duration ablation,but only occurred once in the low-power ablation in the middle cardiac vein,which was near the end of the prescribed time for ablation.Part II Clinical cases:Case 1: A 66-year-old female had idiopathic ventricular premature with the premature load of 26243 beats per 24 hours.Her electrocardiogram showed a right bundle branch block pattern of QRS waves in lead V1,and II,III and a VF showed high R waves.There were "QS" shape with notch in lead I.During electrophysiological study,an irrigated-tip radiofrequency catheter(Thermocool Smarttouch SF;Biosense Webster)was positioned,and a extrasystole electrogram was founded in the distal end of great cardiac vein.V-potential was advanced 21 ms contrasted to onset of QRS wave in electrocardiogram.Radiofrequency energy was applied guided by Carto3 system under high-power short-duration strategy: 45W/5S with an irrigation rate of 30 ml/min,and a total of radiofrequency time was 25 seconds.This arrhythmia was successfully ablated.Case 2: A 48-year-old male suffered from the frequent monomorphic ventricular premature,his dynamic electrocardiogram showed that the premature load was 30698 beats per 24 hours and paroxysmal ventricular tachycardia were manifested of 28 times a day.His electrocardiogram showed a left bundle branch block pattern of QRS waves in lead V1,and II,III and a VF showed high R waves.There were "r" shape with notch in lead I.During electrophysiological study,an irrigated-tip radiofrequency catheter(Thermocool Smarttouch SF;Biosense Webster)was positioned,and a extrasystole electrogram was founded in the distal end of great cardiac vein.V-potential was advanced 27 ms contrasted to onset of QRS wave in electrocardiogram.Radiofrequency energy was applied guided by Carto3 system under high-power short-duration strategy: 45W/5S with an irrigation rate of 30ml/min,and a total of radiofrequency time was 25 seconds.This arrhythmia was successfully ablated.Case 3: A 28-year-old female patient contracted preexcitation syndrome(Wolf-Parkinson-White syndrome)with paroxysmal supra-ventricular tachycardia,her electrocardiogram in sinus rhythm demonstrated pre-excitation(delta or ?)waves located in posterior septum pathway and tachycardia with narrow QRS complex were shown.There were negative ? waves and “QS” pattern with QRS complex in lead?,?,a VF,and QRS complex in lead V1 manifested a “r S” pattern with positive ? wave.During electrophysiological study,orthodromic atrioventricular reentrant tachycardia due to posterior accessory pathway was confirmed and an irrigated-tip radiofrequency catheter was positioned(Thermocool Smarttouch SF;Biosense Webster).A fusion electrogram of ventricular-atrial was founded in middle cardiac vein.V-potential was advanced 30 ms contrasted to onset of ? wave in electrocardiogram.Radiofrequency energy was applied guided by Carto3 system under high-power short-duration strategy: 45W/5S with an irrigation rate of 30 m L/min,and a total of radiofrequency time was 50 seconds.This arrhythmia was successfully ablated.Conclusions: Compared with conventional ablation procedures,high-power short-duration ablation in coronary sinus has the properties of efficacy and safety. |
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