Weizhu Ju

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.

Ventricular Arrhythmias Arising from the Left Ventricular Outflow Tract below the Aortic Sinus Cusps: Mapping and Catheter Ablation via Transseptal Approach and Electrocardiographic Characteristics

Background—Ventricular arrhythmias (VAs) originating from the anterosuperior left ventricular outflow tract (LVOT) represent a challenging location for catheter ablation. This study investigates mapping and ablation of VA from anterosuperior LVOT via a transseptal approach. Methods and Results—This study included 27 patients with symptomatic VA, of which 13 patients had previous failed ablations. LVOT endocardial 3-dimensional mapping via retrograde transaortic and antegrade transseptal approaches was performed. Previous ECG markers for procedure failure were analyzed. In all patients, earliest activation with low-amplitude potentials was identified at the anterosuperior LVOT 5.1±2.8 mm below the aortic cusp and preceded the QRS onset by 39.5±7.7 ms only via an antegrade transseptal approach using a reversed S curve. In all patients, pace mapping failed to demonstrate perfect QRS morphology match. The anatomic location was below the left coronary cusp in 16, below the left coronary cusp/right coronary cusp junction in 8, and below the right coronary cusp in 3 patients. Radiofrequency energy resulted in rapid disappearance of VAs in all patients. ECG analysis showed aVL/aVR Q-wave amplitude ratio >1.4 in 7, lead III/II R-wave amplitude ratio >1.1 in 10, and peak deflection index >0.6 in 11 patients. There were no complications or clinical VA recurrence during a mean follow-up of 8.4±2.5 months. Conclusions—The anterosuperior LVOT can be reached via a transseptal approach with a reversed S curve of the ablation catheter. The rapid effect from radiofrequency energy indicates that the VA is most likely located under the endocardium. Also, previous ECG markers for procedure failure need further investigation.

Transvenous Phrenic Nerve Stimulation in Patients With Cheyne-Stokes Respiration and Congestive Heart Failure A Safety and Proof-of-Concept Study

BACKGROUND Cheyne-Stokes respiration (CSR), which often occurs in patients with congestive heart failure (CHF), may be a predictor for poor outcome. Phrenic nerve stimulation (PNS) may interrupt CSR in patients with CHF. We report the clinical use of transvenous PNS in patients with CHF and CSR. METHODS Nineteen patients with CHF and CSR were enrolled. A single stimulation lead was placed at the junction between the superior vena cava and brachiocephalic vein or in the left-side pericardiophrenic vein. PNS stimulation was performed using Eupnea System device (RespiCardia Inc). Respiratory properties were assessed before and during PNS. PNS was assessed at a maximum of 10 mA. RESULTS Successful stimulation capture was achieved in 16 patients. Failure to capture occurred in three patients because of dislocation of leads. No adverse events were seen under maximum normal stimulation parameters for an overnight study. When PNS was applied following a series of central sleep apneic events, a trend toward stabilization of breathing and heart rate as well as improvement in oxygen saturation was seen. Compared with pre-PNS, during PNS there was a significant decrease in apnea-hypopnea index (33.8 ± 9.3 vs 8.1 ± 2.3, P = .00), an increase in mean and minimal oxygen saturation as measured by pulse oximetry (89.7% ± 1.6% vs 94.3% ± 0.9% and 80.3% ± 3.7% vs 88.5% ± 3.3%, respectively, all P = .00) and end-tidal CO2 (38.0 ± 4.3 mm Hg vs 40.3 ± 3.1 mm Hg, P = .02), but no significant difference in sleep efficiency (74.6% ± 4.1% vs 73.7% ± 5.4%, P = .36). CONCLUSIONS The preliminary results showed that in a small group of patients with CHF and CSR, 1 night of unilateral transvenous PNS improved indices of CSR and was not associated with adverse events.

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.

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.