Noncontact Mapping for Radiofrequency Ablation of Complex Cardiac Arrhythmias

Radiofrequency (RF) catheter ablation is the current treatment of choice for several cardiac arrhythmias. The conventional approach utilizing intracardiac electrograms during sinus rhythm and during tachycardia has inherent limitations, including limited two-dimensional fluoroscopic imaging and limited ability to evaluate several potential sites for ablation then go precisely to the most suitable site. Recently, a noncontact mapping system has been developed that can be used to perform single beat high resolution mapping of cardiac arrhythmias. In this report, we describe the advantage of utilizing the system in facilitating a successful outcome in 5 patients with different complex arrhythmias.     

Electroanatomic Mapping for Radiofrequency Ablation of Cardiac Arrhythmias

Radiofrequency catheter ablation is the current treatment of choice for several cardiac arrhythmias. The conventional approach utilizing intracardiac electrograms during sinus rhythm and during tachycardia has inherent limitations including limited two-dimensional fluoroscopic imaging and the ability to evaluate several potential sites for ablation and to go precisely to the most suitable site. Recently, a nonfluoroscopic three-dimensional electroanatomic system has been developed for mapping arrhythmias. We describe in this report the advantage of utilizing the system in facilitating a successful outcome in three patients with different arrhythmias.     

Noncontact Endocardial Mapping: Reconstruction of Electrograms and Isochrones From Intracavitary Probe Potentials

Noncontact Endocardial Mapping. Introduction : Mapping endocardial activation and repolarization processes is critical to the study of arrhythmias and selection of therapeutic procedures. Previously, we developed methodology for reconstructing endocardial potentials from potentials measured with a noncontact, intracavitary probe. This study further develops and evaluates the ability of the approach to provide detailed information on the spatiotemporal characteristics of the activation process. Specifically, we reconstructed endocardial electrograms and isochrones throughout the activation process over the entire endocardium during a single beat.
Methods and Results : Cavity potentials were measured with a 65-electrode probe placed inside an isolated canine left ventricle. Endocardial potentials were measured simultaneously using 52 electrodes. Potentials were acquired during subendocardial pacing from different locations. Computed electrograms at various sites closely resemble the measured electrograms (correlation coefficient > 0.9 at 60% of the electrodes). Computed isochrones locate subendocardial pacing sites with 10-mm accuracy. Two pacing sites, 17 mm apart, were resolved. Critical regions, such as areas of isochrone crowding, were accurately reconstructed.
Conclusions : Results indicate the applicability of the approach to mapping the cardiac excitation process on a beat-by-beat basis without occluding the ventricle. The ability of locating electrical events (e.g., single or multiple initiation sites) is demonstrated. Importantly, the method is shown to be capable of reconstructing electrograms over the entire endocardium and determining nonuniformities of activation spread (e.g., areas of slow conduction). These capabilities are important to clinical application in the electrophysiology laboratory and experimental studies of arrhythmias in the intact animal.     

非接触标测在室性心动过速消融中的应用

非接触球囊标测系统以其独有的优势展现了全新的电生理标测方法,在多种心律失常的消融过程中,扮演着重要角色,尤其是室性心律失常的消融,现对非接触球囊标测系统的特点及在室性心动过速消融中的作用分别总结和叙述。     

Use of Three-Dimensional Mapping Systems in the Catheter Ablation of Atrial Fibrillation

The increasing clinical experience with remarkable advancement in the technology has enabled the catheter ablation of atrial fibrillation (AF) to become more effective and safe. Widespread utilization of three-dimensional (3D) mapping systems has facilitated the improvement in the outcomes after catheter ablation of AF. The purpose of this article is to review the current status, clinical role, and future directions of various 3D mapping systems in catheter ablation of AF.     

Nonfluoroscopic Catheter Ablation of Cardiac Arrhythmias in Adults: Feasibility,Safety, and Efficacy

Nonfluoroscopic Catheter Ablation of Cardiac Arrhythmias in Adults Background: Catheter ablations are traditionally performed using fluoroscopic guidance, exposing both patients and medical staff to the risks of radiation. Nonfluoroscopic catheter ablation has been used successfully to treat limited types of arrhythmias in children, but whether this approach has broad application in adults is uncertain. The purpose of this study was to evaluate the feasibility, safety, and efficacy of fluoroless catheter ablation in adults being treated for a range of arrhythmias. Methods and Results: Retrospective analysis was performed in 2 patient groups (both n = 60): (1) the nonfluoroscopy (NF) group consisting of consecutive adult patients, in which catheter positioning was accomplished exclusively with intracardiac electrograms (IE), electroanatomic mapping (EAM), and intracardiac echocardiography (ICE); and (2) the fluoroscopy (F) group, in which catheter positioning was additionally guided by fluoroscopy. The patients in the F group were selected to match the types of arrhythmias in the NF group. All ablation procedures were performed by one operator. The total procedure time did not differ between groups for any specific type of arrhythmia ablated. Acute procedural success was similar in both groups (NF, 59/60 [98%] and F, 60/60 [100%]). The complications were limited to a groin pseudoaneurysm in the NF group, and pericardial effusion and groin hematoma in the F group. Conclusion: Catheter ablations were efficiently and effectively performed in adults with a variety of arrhythmias using only IE, EAM, and ICE for catheter guidance. This nonfluoroscopic technique was feasible, posed no additional safety concerns, and should be readily implementable in most electrophysiology laboratories. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1078‐1086, October 2012)     

Electroanatomic Mapping of the Right Coronary Artery: A Novel Approach to Ablation of Right Free-Wall Accessory Pathways

Background: Catheter ablation of right free-wall (RFW) accessory pathways continues to be associated with lower success and higher recurrence rates compared with other pathway locations. Reliably identifying the precise location of RFW accessory pathways often contributes to the difficulty in ablating these pathways. Improved localization of RFW accessory pathways has been described utilizing multielectrode right coronary artery (RCA) catheterization. This approach has not been widely adopted, in part due to concerns of prolonged catheter placement within the RCA. We describe the technique of creating a 3-D electroanatomic map of the right atrioventricular groove, limiting the duration of a microcatheter within the RCA, to facilitate ablation of RFW accessory pathways.
Methods and Results: Following intracardiac identification of a RFW accessory pathway, an octapolar microcatheter was placed in the RCA. A 3-D electroanatomic map of the RCA was created during retrograde accessory pathway conduction using ventricular pacing. Immediately following creation of the map, the RCA catheter was removed. Endocardial mapping and ablation of the RFW accessory pathway was performed using the RCA electroanatomic map as a guide. This technique was used in four pediatric patients. The microcatheter was within the RCA for less than 1 min in all patients. Radiofrequency catheter ablation of the RFW accessory pathways were successfully performed with two lesions. There were no complications or recurrences at follow-up.
Conclusions: The creation of a 3-D electroanantomic map of the RCA effectively localizes RFW accessory pathways and facilitates successful ablation. This technique minimizes the duration of RCA instrumentation.     

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. Methods and Results: Eleven patients with RFW APs that failed initial conventional catheter ablation(s) by a mean of 1.9 ± 0.5 attempts were enrolled in the study. Electroanatomic mapping of the right atrium was performed during orthodromic reciprocating tachycardia in 3 patients and right ventricular pacing in 8 patients. The earliest atrial activation site, which represented the atrial insertion of the AP, was separated from the tricuspid annulus by an average of 14.3 ± 3.9 mm, and the local activation time was 27.8 ± 17.0 ms earlier than that of the corresponding annular point. One patient exhibited an AP with wide branching on the atrial side. RF ablation with an irrigated catheter successfully interrupted AP conduction in all patients without complications. Conclusions: RFW APs resistant to conventional catheter ablation might be due to unique anatomic AP features such as more epicardial course at the annulus level with atrial insertion distant from the tricuspid annulus. Electroanatomic mapping is helpful to accurately localize the atrial insertion sites of these APs and facilitates catheter ablation. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1317‐1324, December 2010)     

Infusion Needle Radiofrequency Ablation for Treatment of Refractory Ventricular Arrhythmias

Background

Catheter ablation is effective for eliminating most drug-refractory ventricular arrhythmias (VA). However, a major reason for procedural failure is arrhythmia originating deep within the myocardium where it is inaccessible to conventional endocardial or epicardial approaches. Affected patients have limited therapeutic options.

Endocardial and Epicardial Ablation Guided by Nonsurgical Transthoracic Epicardial Mapping to Treat Recurrent Ventricular Tachycardia

Nonsurgical Epicardial Ablation. Introduction : An epicardial site of origin of ventricular tachycardia (VT) may explain unsuccessful endocardial radiofrequency (RF) catheter ablation. A new technique to map the epicardial surface of the heart through pericardial puncture was presented recently and opened the possibility of using epicardial mapping to guide endocardial ablation or epicardial catheter ablation. We report the efficacy and safety of these two approaches to treat 10 consecutive patients with VT and Chagas' disease.
Methods and Results : Epicardial mapping was carried out with a regular steerable catheter introduced into the pericardial space. An epicardial circuit was found in 14 of 18 mapable VTs induced in 10 patients. Epicardial mapping was used to guide endocardial ablation in 4 patients and epicardial ablation in 6. The epicardial earliest activation site occurred 107 ± 60 msec earlier than the onset of the QRS complex. At the epicardial site used to guide endocardial ablation, earliest activation occurred 75 ± 55 msec before the QRS complex. Epicardial mid-diastolic potentials and/or continuous electrical activity were seen in 7 patients. After 4.8 ± 2.9 seconds of epicardial RF applications, VT was rendered noninducible. Hemopericardium requiring drainage occurred in 1 patient; 3 others developed pericardial friction without hemopericardium. Patients remain asymptomatic 5 to 9 months after the procedure. Interruption during endocardial pulses occurred after 20.2 ± 14 seconds (P = 0.004), hut VT was always reinducible and the patients experienced a poor outcome.
Conclusion : Epicardial mapping does not enhance the effectiveness of endocardial pulses of RF. Epicardial applications of RF energy can safely and effectively treat patients with VT and Chagas' disease.     

Value of dynamic substrate mapping to identify the critical diastolic pathway in postoperative ventricular reentrant tachycardias after surgical repair of tetralogy of fallot

Characterization of the Critical Isthmus in VT in TOF. Introduction: The complexity of postoperative ventricular reentrant tachycardias may limit success of catheter ablation. The objective of this analysis was to compare the usefulness of dynamic substrate mapping (DSM) versus color‐coded isopotential mapping of the noncontact mapping system for the identification of the critical diastolic pathway of postoperative ventricular reentrant tachycardias (VT) after surgical repair of tetralogy of Fallot (TOF). Methods: Postoperative VT had been studied applying isopotential maps with the noncontact mapping system EnSite in 7 patients, and radiofrequency current lesion lines had been applied across the shortest isthmus to target during sinus rhythm. Data of the noncontact mapping system were reanalyzed applying the DSM algorithm. For DSM, a 2‐Hz filter and color settings between 0 mV and 50% of peak negative voltage (PNV) with autofocus turned off were used. DSM was initially applied over the QRS complex duration during sinus rhythm. Abnormal myocardium was defined as <35–40% of PNV. DSM was subsequently applied to ventricular diastole during the final 33% of VT cycle length. Areas with >70% of PNV within this time frame were to identify the critical diastolic pathway. Results: Applying DSM, the critical diastolic pathway of the VT was identified in all 7 patients that corresponded to the regions targeted for ablation. Conclusion: By focusing the time reference to electrical diastole, when the VT wavefront is moving through the low‐voltage area, the region of greatest relative voltage could be highlighted, which corresponded to the diastolic pathway. (J Cardiovasc Electrophysiol, Vol. 23, pp. 930‐937, September 2012)     

Mapping and Ablation of Frequent Post‐Infarction Premature Ventricular Complexes

Mapping of Post‐Infarction PVCs . Introduction: Premature ventricular complexes (PVCs) occur frequently in patients with heart disease. The sites of origin of PVCs in patients with prior myocardial infarction and the response to catheter ablation have not been systematically assessed. Methods and Results: In 28 consecutive patients (24 men, age 60 ± 10, ejection fraction [EF] 0.37 ± 0.14) with remote myocardial infarction referred for catheter ablation of symptomatic refractory PVCs, the PVCs were mapped by activation mapping or pace mapping using an irrigated‐tip catheter in conjunction with an electroanatomic mapping system. The site of origin (SOO) was classified as being within low‐voltage (scar) tissue (amplitude ≤1.5 mV) or tissue with preserved voltage (>1.5 mV). The SOO was confined to endocardial scar tissue in 24/28 patients (86%). The SOO was outside of scar in 3 patients and could not be identified in 1 patient. At the SOO, local endocardial activation preceded the PVC by 46 ± 19 ms, and the electrogram amplitude during sinus rhythm was 0.48 ± 0.34 mV. The PVCs were effectively ablated in 25/28 patients (89%), resulting in a decrease in PVC burden on a 24‐hour Holter monitor from 15.6 ± 12.3% to 2.4 ± 4.2% (P < 0.001). The SOO most often was confined to scar tissue located in the left ventricular septum and the papillary muscles. Conclusion: Similar to post‐infarction ventricular tachycardia, PVCs after remote myocardial infarction most often originate within scar tissue. Catheter ablation of these PVCs has a high‐success rate. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1002‐1008, September 2010)