Background Verapamil-sensitive, idiopathic left ventricular tachycardia （ILVT） with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of re...Background Verapamil-sensitive, idiopathic left ventricular tachycardia （ILVT） with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated. Radiofrequency （RF） ablation was applied during ventricular tachycardia （VT） and termination of the VT or abolishing the inducibility of the tachycardia was used as an endpoint for successful RF. In this study, the left posterior fascicular block in surface electrocardiogram （ECG） was used as a new endpoint of ablation to cure ILVT. Methods Electrophysiological studies and radiofrequency ablation were performed in 39 consecutive patients [30 men, 9 women; age ranging from 10 to 64 years, mean （29± 16） years] with verapamil-sensitive ILVT and structurally normal hearts. VT could be terminated by the intravenous adininistration of verapamil in all patients. The target site was the midseptum of LV where the earliest Purkinje potentials were recorded during VT. RF current was applied to the target site with or without late diastolic potential （LDP） during sinus rhythm in 37 patients and during VT in 2 patients to meet the ablation endpoint： the left posterior fascicuiar block in the surface ECG. Results Thirty-seven patients with ILVT had been treated by RF ablation during sinus rhythm and two had been treated during VT. All of them met the endpoint of the left posterior fascicuiar block. Thirty-eight cases were symptom-free without medications during the follow-up period （range from 3 to 95 months, median 17 months）. One patient developed a clinical recurrence and the left posterior fascicuiar block in surface ECG disappeared. The patient received another treatment. The endpoint was met and the procedure was successful. Conclusions The left posterior fascicuiar block in surface ECG used as an endpoint of RF ablation to treat ILVT is effective. It is important especially in those patients whose VT can not be induced or the inducible condition is unstable. The effective endpoint implied that the left posterior fascicle might be a critical part of the re-entrant circuit.展开更多
Left anterior fascicular block（LAFB） is a heart disease identifiable from an abnormal electrocardiogram（ECG）. It has been reported that LAFB is associated with an increased risk of heart failure. Non-specific intr...Left anterior fascicular block（LAFB） is a heart disease identifiable from an abnormal electrocardiogram（ECG）. It has been reported that LAFB is associated with an increased risk of heart failure. Non-specific intraventricular conduction delay due to the lesions of the conduction bundles and slow cell to cell conduction has also been considered as another cause of heart failure. Since the location and mechanism of conduction delay have notable variability between individual patients, we hypothesized that the impaired conduction in the ventricular myocardium may lead to abnormal ECGs similar to LAFB ECG patterns. To test this hypothesis, based on a computer model with a three dimensional whole-heart anatomical structure, we simulated the cardiac exciting sequence map and 12-lead ECG caused by the block in the left anterior fascicle and by the slowed conduction velocity in the ventricular myocardium. The simulation results showed that the typical LAFB ECG patterns can also be observed from cases with slowed conduction velocity in the ventricular myocardium. The main differences were the duration of QRS and wave amplitude. In conclusion, our simulations provide a promising starting point to further investigate the underlying mechanism of heart failure with LAFB, which would provide a potential reference for LAFB diagnosis.展开更多
文摘Background Verapamil-sensitive, idiopathic left ventricular tachycardia （ILVT） with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated. Radiofrequency （RF） ablation was applied during ventricular tachycardia （VT） and termination of the VT or abolishing the inducibility of the tachycardia was used as an endpoint for successful RF. In this study, the left posterior fascicular block in surface electrocardiogram （ECG） was used as a new endpoint of ablation to cure ILVT. Methods Electrophysiological studies and radiofrequency ablation were performed in 39 consecutive patients [30 men, 9 women; age ranging from 10 to 64 years, mean （29± 16） years] with verapamil-sensitive ILVT and structurally normal hearts. VT could be terminated by the intravenous adininistration of verapamil in all patients. The target site was the midseptum of LV where the earliest Purkinje potentials were recorded during VT. RF current was applied to the target site with or without late diastolic potential （LDP） during sinus rhythm in 37 patients and during VT in 2 patients to meet the ablation endpoint： the left posterior fascicuiar block in the surface ECG. Results Thirty-seven patients with ILVT had been treated by RF ablation during sinus rhythm and two had been treated during VT. All of them met the endpoint of the left posterior fascicuiar block. Thirty-eight cases were symptom-free without medications during the follow-up period （range from 3 to 95 months, median 17 months）. One patient developed a clinical recurrence and the left posterior fascicuiar block in surface ECG disappeared. The patient received another treatment. The endpoint was met and the procedure was successful. Conclusions The left posterior fascicuiar block in surface ECG used as an endpoint of RF ablation to treat ILVT is effective. It is important especially in those patients whose VT can not be induced or the inducible condition is unstable. The effective endpoint implied that the left posterior fascicle might be a critical part of the re-entrant circuit.
基金Project supported by the National Natural Science Foundation of China(Nos.61527811 and 61701435)
文摘Left anterior fascicular block（LAFB） is a heart disease identifiable from an abnormal electrocardiogram（ECG）. It has been reported that LAFB is associated with an increased risk of heart failure. Non-specific intraventricular conduction delay due to the lesions of the conduction bundles and slow cell to cell conduction has also been considered as another cause of heart failure. Since the location and mechanism of conduction delay have notable variability between individual patients, we hypothesized that the impaired conduction in the ventricular myocardium may lead to abnormal ECGs similar to LAFB ECG patterns. To test this hypothesis, based on a computer model with a three dimensional whole-heart anatomical structure, we simulated the cardiac exciting sequence map and 12-lead ECG caused by the block in the left anterior fascicle and by the slowed conduction velocity in the ventricular myocardium. The simulation results showed that the typical LAFB ECG patterns can also be observed from cases with slowed conduction velocity in the ventricular myocardium. The main differences were the duration of QRS and wave amplitude. In conclusion, our simulations provide a promising starting point to further investigate the underlying mechanism of heart failure with LAFB, which would provide a potential reference for LAFB diagnosis.
