The Study Of The Effectiveness Of The Radiofrequency Catheter Ablation For The Treatment Of Ventricular Electrical Storm In The Patients With Implantable Cardioverter Defibrillator

Objective:Radiofrequency catheter ablation(RFCA)has emerged as an important approach for the treatment of electrical storm following the procedure with implantable cardioverter defibrillator(ICD).The approach of operation and follow-up results of 22 patients who received Radiofrequency catheter ablation for electrical storm following procedure with ICD in our hospital were retrospectively analyzed to investigate the effectiveness and safety of catheter-based RFA.Methods:1 case was considered to be idiopathic left ventricular outflow tract tachycardia before procedure and received activation mapping and pacing mapping.The other 21 cases received endocardial voltage mapping in the sinus rhythm and were determined for local abnormal ventricular activities.If voltage mapping indicated no low-voltage region,the activation mapping and pacing mapping were combined to identify the target.If no ideal target was found,epicardial approach was established to perform voltage mapping,activation and pacing mapping.All patients received programmed stimulation to induce clinical ventricular tachycardia(VT)before ablation.If a significant low-voltage region was found by voltage mapping and confirmed to be associated with VT by pacing mapping,then it was not necessary to find slow conduction zone or critical isthmus.In this case,the matrix of the low-voltage region was refined and the local abnormal ventricular activities,area in the low-voltage region was the focus for ablation.If there was no low-voltage region,then the ideal target under pacing and activation mapping was ablated.The inability to induce tachycardia by ventricular programmed stimulation on multiple sites and intravenous drip with isoproterenol indicated the endpoint of all ablation types.All patients received programmed of the inplantable cardioverter defibrillators and follow-up via calls.Results:There were 20 male cases and 2 female cases with mean age of(53.39± 13.99)included in the study.6 cases had dilated cardiomyopathy.6 cases had ischemic cardiomyopathy.2 cases had Brugada syndrome.3 cases had arrhythmogenic right ventricular cardiomyopathy.1 case had non-compaction of ventricular myocardium.4 cases had no definite structural heart diseases.1 week before ablation,these patients had(14.5±14.9)events of VT and received(9.3±9.9)ICD/CRT-D treatments.16 cases received endocardial mapping only.6 cases received endocardial mapping combined with epicardial mapping.A total of 26 procedures were performed.22 cases had all VTs ablated during procedure.1 case had clinical VT ablated,but unsustained still could be triggered Clinical VT could be induced in 3 cases after procedure.The complete success rate immediately of ablation was 84.6%(22/26).The partial success rate immediately was 3.9%(1/26).The failure rate immediately was 11.5%(3/26).The overall immediate effective rate of the procedure was 88.5%(23/26).The patients received follow-up for(21.6±12.1)months after last procedure.5 cases had recurrent VT,including 4 cases with ventricular electrical storm,and 1 case had recurrent VT but without electrical storm(because decreased VT frequency did not trigger anti-arrhythmic treatment by ICD)During follow-up,4 cases died.The death in 3 cases was associated with recurrent electrical storm.1 case died of respiratory failure and did not have recurrent VT and electrical storm at death.The long-term complete success rate,partial success rate and failure rate of catheter ablation were 77.3%(17/22),4.5%(1/22)and 18.2%(4/22),respectively.The overall effective rate was 81.8%(18/22).Severe complications such as pericardial tamponade were not observed in patients during and after procedures.Conclusions:First,catheter-based RFA is a safe and effective treatment for electrical storm following ICD procedure.It can significantly reduce the occurrence of electrical storm and VT.Second,the presence of low-voltage region and local abnormal ventricular activities is the foundation for the onset of electrical storm in organic heart disease and hereditary ion channel disease.The modification of matrix is the most important factor to achieve successful ablation.Third,for refractory VT,epicardial mapping and ablation can be considered when endocardial ablation is not effective.Fourth,the different characteristics of underlying heart diseases can be combined to help identify the region of interest and map target for ablation,hence saving time of procedure and reduce the incidence of procedure-related complications.