Hongwu Chen

Electrocardiographic algorithm to identify the optimal target ablation site for idiopathic right ventricular outflow tract ventricular premature contraction

AIMS Several electrocardiographic (ECG) algorithms have been developed to identify the site of origin of ventricular premature contractions (VPCs) from right ventricular outflow tract (RVOT) based on pacemapping; however, their accuracy remains unclear. METHODS AND RESULTS We evaluated the accuracy of these algorithms in 52 consecutive patients (31 female, mean age 42.6+/-14.6 years) with successful radiofrequency ablation of RVOT-VPC as guided by 3D electroanatomical non-contact mapping (Ensite, St Jude Medical, USA) and compared with a newly proposed ECG algorithm. As guided by 3D electroanatomical mapping, the successful ablation sites of RVOT-VPC were RVOT septum (n=31), RVOT free wall (n=19), and His region (n=2). Retrospective evaluation in the initial 39 patients shows that the overall positive prediction value to identify a successful ablation site of this newly proposed ECG algorithm is 77.3% and is higher than the 73.3% by Ito et al., 73.3% by Joshi et al., and 53.8% by Dixit et al. (P>0.05). Prospective evaluation in the subsequent 13 patients also demonstrate similar high overall sensitivity (79.0%), specificity (92.7%), and positive prediction value (88.2%) to identify a successful ablation site with this newly proposed ECG algorithm. CONCLUSION On the basis of detail 3D electroanatomical mapping of successful ablation sites, a newly proposed ECG algorithm was developed to improve the sensitivity, specificity, and positive prediction value in identification of targeted ablation sites for RVOT-VPC.

Catheter Ablation of Nonparoxysmal Atrial Fibrillation Using Electrophysiologically Guided Substrate Modification During Sinus Rhythm After Pulmonary Vein Isolation

Background—The high incidence of postprocedural atrial tachycardia reduces the absolute arrhythmia-free success rate of extensive ablation strategies to treat nonparoxysmal atrial fibrillation (NPAF). We hypothesized that a strategy of targeting low-voltage zones and sites with abnormal electrograms during sinus rhythm (SR-AEs) in the left atrium after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation in patients with NPAF is superior. Methods and Results—A total of 86 consecutive patients with NPAF were enrolled in study group. After circumferential pulmonary vein isolation, cavotricuspid isthmus ablation and cardioversion to SR, high-density mapping of left atrium was performed. Areas with low-voltage zone and SR-AE were targeted for further homogenization and elimination, respectively; 78 consecutive sex- and age-matched patients with NPAF who were treated with the stepwise approach served as the historical control group. In the study group, 92% (79/86) were successfully cardioverted after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation. Among the patients converted to SR, 70% (55/79) had low-voltage zone and SR-AE and received additional ablation, whereas in 30% (24/79) without SR-AE or low-voltage zone, no further ablation was performed. During a follow-up period of >30 months, the Kaplan–Meier estimated probability to maintain SR at 24 months was 69.8% versus 51.3%. And after a single procedure, 3.5% (3/86) developed postprocedural atrial tachycardia in study group, compared with 30% (24/78) in control group (P=0.0003). Conclusions—A strategy of selective electrophysiologically guided atrial substrate modification in SR after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation is clinically more effective than the stepwise approach for NPAF ablation. Clinical Trial Registration—URL: http://clinicaltrials.gov. Unique identifier: NCT01716143.

Connexin43 promotes survival of mesenchymal stem cells in ischaemic heart

The involvement of connexins in regulating cell growth and death has recently been reported. We have investigated whether Cx43 (connexin43) contributes to MSC (mesenchymal stem cell) survival and improves therapeutic efficacy in MI (myocardial infarction). Genetically modified Cx43 MSCs were exposed to hypoxic conditions or injected intramyocardially into a rat MI model. MSCs overexpressing Cx43, with more Bcl-2 and phosphorylated Akt, but less Bax, were relatively tolerant to hypoxic injury. After transplantation, this Cx43 overexpression enhanced cell survival and reduced infarct size, improving contractile performance. Cx43 inhibition by SiRNA reversed the effects of Cx43 overexpression. Therefore, Cx43 may act as a potential target for improving the therapeutic efficacy of MSCs in ischaemic heart disease.

Catheter Ablation of Fascicular Ventricular Tachycardia Long-Term Clinical Outcomes and Mechanisms of Recurrence

Background—Fascicular ventricular tachycardia (FVT) is a common form of sustained idiopathic left ventricular tachycardia with an Asian preponderance. This study aimed to prospectively investigate long-term clinical outcomes of patients undergoing ablation of FVT and identify predictors of arrhythmia recurrence. Methods and Results—Consecutive patients undergoing FVT ablation at a single tertiary center were enrolled. Activation mapping was performed to identify the earliest presystolic Purkinje potential during FVT that was targeted by radiofrequency ablation. Follow-up with clinic visits, ECG, and Holter monitoring was performed at least every 6 months. A total of 120 consecutive patients (mean age, 29.3±12.7 years; 82% men; all patients with normal ejection fraction) were enrolled. FVT involved left posterior fascicle and left anterior fascicle in 118 and 2 subjects, respectively. VT was noninducible in 3 patients, and ablation was acutely successful in 117 patients. With a median follow-up of 55.7 months, VT of a similar ECG morphology recurred in 17 patients, and repeat procedure confirmed FVT recurrence involving the same fascicle. Shorter VT cycle length was the only significant predictor of FVT recurrence (P=0.03). Six other patients developed new-onset upper septal FVT that was successfully ablated. Conclusions—Ablation of FVT guided by activation mapping is associated with a single procedural success rate without the use of antiarrhythmic drugs of 80.3%. Arrhythmia recurrences after an initially successful ablation were caused by recurrent FVT involving the same fascicle in two thirds of patients or new onset of upper septal FVT in the remainder.

Localized Reentry as a Novel Type of the Proarrhythmic Effects of Linear Ablation in the Left Atrium

Background: There is a consistent understanding that the proarrhythmic effect of linear ablation in the left atrium body for atrial fibrillation (AF) always manifests as the macroreentry tachycardia. However, its genesis of localized reentry has been underestimated.

Knowledge, attitude, and behavior in patients with atrial fibrillation undergoing radiofrequency catheter ablation

PurposeCatheter ablation for atrial fibrillation (AF) has become a widely accepted procedure in most of the large cardiac centers throughout the world. However, little is known regarding the knowledge, attitude, and behavior (KAB) of AF patients undergoing radiofrequency catheter ablation (RFCA). Our purpose is to investigate the status and influencing factors of KAB in these patients.MethodsWe conducted a KAB survey utilizing specifically designed questionnaires among hospitalized AF patients undergoing RFCA from July 2008 to April 2009.ResultsA total of 116 AF participants were enrolled and 113 were effective sample, the response rate was 97%. Only 47% of the participants answered questions regarding knowledge about AF correctly. Knowledge deficits were greater in male patients, poorly educated and first-time RFCA patients. With regard to attitude, 45% of participants considered daily pulse examination to be unnecessary. Higher knowledge scores, persistent AF and AF recurrence were positive predictors of attitude. Despite adherence to take medication was high, more than half of the participants demonstrated poor monitor behavior. Knowledge, attitude, and the number of previous attempts at RFCA were factors affecting the self-management behavior.ConclusionsAF patients undergoing RFCA have knowledge deficits in general and there is a lack of consistency among their KAB. In order to establish a better attitude and self-management behavior, AF patients undergoing RFCA need comprehensive education by the KAB questionnaire according to the KAB theory.

Right-Sided Free Wall Accessory Pathway Refractory to Conventional Catheter Ablation: Lessons From 3-Dimensional Electroanatomic Mapping

Right Free Wall Accessory Pathway Ablation. Introduction: The aim of this study was to delineate the electroanatomic substrates of right‐sided free wall (RFW) accessory pathways (APs) that were refractory to conventional catheter ablation utilizing 3‐dimensional (3‐D) mapping.

Long‐Term Outcome Following Ablation of Atrial Tachycardias Occurring after Mitral Valve Replacement in Patients with Rheumatic Heart Disease

Atrial tachycardia (AT) is a frequent late sequel of surgical valve replacement procedures in patients with rheumatic heart disease (RHD). The aim of this study was to evaluate the acute and long‐term outcome of catheter ablation in such patients.

Does linear ablation and defragmentation really improve the success rate of persistent AF? Follow-up results and electrophysiological findings from 169 consecutive patients

BACKGROUND Catheter ablation of persistent atrial fibrillation (AF) has been performed with varying results using a combination of different techniques. We sought to evaluate the efficacy of additional linear lesion and defragmentation of left atrium (LA). METHODS A cohort of 169 patients with persistent AF was studied. Ablation was performed following a sequential strategy consisted of circumferential pulmonary vein isolation (CPVI), LA roof linear ablation, posterior mitral area, coronary sinus and cavotricuspid isthmus, and complex fractionated electrograms ablation. RESULTS During a mean follow-up of 15 ± 8 months after a single procedure, 84 (50%) patients were in sinus rhythm, 34 (20%) had an AF recurrence and 51(30%) developed atrial tachycardias (ATs). Repeat procedures were performed in 24 recurrent AF and 46 AT patients. A total of 81 different ATs were mapped and ablated in 46 AT patients, characterized as focal for 45 and macroreentry for 36 ATs. Most of the ATs were likely to be attributed to the previous lesions by an analysis of substrate and activation mapping in the redo procedure and a review of the lesions placed in the initial procedure. Overall, 75 (93%) ATs were ablated successfully. Procedural complications occurred in 11 of the 239 procedures. After a mean follow-up of 20 ± 9 months, 128 (76%) patients were free of arrhythmias after the final procedure. CONCLUSIONS CPVI supplemented by linear ablation and defragmentation does not seem to improve the overall success rate of persistent AF. The efficacy of linear ablation and defragmentation might be diluted by their proarrhythmic effects.

A novel method to identify the origin of ventricular tachycardia from the left fascicular system

BACKGROUND There are well-described ablation strategies to treat left fascicular tachyarrhythmia (LFTA); however, a method to predict the origin is less well characterized. OBJECTIVE The purpose of this study was to predict the origin of LFTAs by measuring the HV interval during normal sinus rhythm (NSR) and LFTAs. METHODS A predicted value of the earliest presystolic potential (PP) time was calculated using the HV interval during NSR and LFTAs [(HVNSR+HVLFTA)/2]. The earliest retrograde PP was mapped during LFTAs, and the relationship between the predicted and the mapped value was correlated. RESULTS Twenty-one consecutive patients with LFTAs were included in this study. Four patients (19%) had tachycardia originating from the left anterior fascicle; the mean HV interval was 50.3 ± 8.3 and 30.3 ± 11.6 ms during NSR and tachycardia, respectively. The mapped retrograde PP during LFTAs preceded the onset of the surface electrocardiogram by 34 ± 9.4 ms. Seventeen patients (81%) had tachycardia originating from the left posterior fascicle; the mean HV interval was 49.2 ± 4.6 and -4.5 ± 13.6 ms during NSR and LFTAs, respectively. Nineteen patients with successful ablation were analyzed; the mean HV interval was -0.9 ± 16.8 and 49.5 ± 4.6 ms during LFTAs and NSR, respectively. The predicted value was similar to the mapped value (24.4 ± 9.1 ms vs 25.2 ± 8.1 ms; P = .76). The predicted value was well correlated with that from the target site (r = 0.97; P < .001). CONCLUSION The earliest retrograde PP site for the ablation of LFTAs can be predicted measuring the HV interval during NSR and LFTAs. Successful ablation can be performed during NSR for patients with LFTAs inducible at baseline but noninducible during mapping.