A Nonfluoroscopic Catheter-Based Mapping Technique to Ablate Focal Ventricular Tachycardia

The recent introduction of a nonfluoroscopic electroanatomical cardiac mapping system (CARTO) is an exciting development in catheter ablation treatment of cardiac arrhythmias. The system uses ultralow magnetic fields to locate a sensor positioned near the tip of a regular mapping and ablation catheter. The catheter location and electrograms are recorded and reconstructed in real-time and presented as a three-dimensional geometrical mapped color coded with the electrophysiological information. The CARTO represents an important tool to guide the ablation of patients who have focal tachycardia (e.g., right ventricular outflow tract [RVOT] tachycardia and idiopathic left ventricular [ILV] tachycardia). This study describes how the CARTO system is useful in mapping and ablating these arrhythmias. Two case illustrations, one patient with RVOT tachycardia and another with ILV tachycardia, are described in this article. The tachycardia was mapped and ablated using the new electromagnetic catheter technology creating an electroanatomical map of the arrhythmia focus for each tachycardia without fluoroscopy; both tachycardias were successfully ablated, terminated, and rendered noninducible. The CARTO system is useful in mapping and guiding the ablation of focal tachycardia and merits further study.     

Endocardial Catheter Ablation for Refractory Ventricular Tachycardia Associated with Coronary Artery Disease

Percutaneous endocardial electrode catheter ablation using stored direct current (DC) electrical energy was performed in five patients with recurrent ventricular tachycardia (VT) refractory to many antiarrhythmic drugs, including amiodarone. All had prior myocardial infarction and poor left ventricular function with ejection fractions ranging from 20% to 40%. Endocardial catheter and pace mappings were used to localize the earliest site of activation during VT. Under general anesthesia, two to six shocks with 200 to 300 joules DC energy per shock were delivered to the localized sites. Immediate complications included ventricular fibrillation in one patient, transient QRS complex widening in two patients, transient complete AV block with persistent first-degree AV block in one patient, and transient asystole in two patients. None had inducible VT immediately following ablation, or 4 to 6 days later; none had evidence of intracardiac clot by two-dimensional (2D) echocardiography on the third to fifth day. Peak creatine kinase ranged from 189 to 1610 IU/L with 9% to 18% MB fraction. During a follow-up of 6 to 30 months, three patients had no recurrence of VT. Two patients had recurrent VT with a slower rate, which was controlled with antiarrhythmic drugs. None had worsening of congestive heart failure. Two patients died of nonarrhythmic causes. We conclude that nonsurgical endocardial ablation of VT with an electrode catheter is effective for the treatment of refractory VT in selected patients with coronary artery disease.     

三维电解剖标测系统指导下射频消融房性心动过速的临床研究

目的：探讨三维电解剖标测系统（CARTO）指导下进行房性心动过速射频消融的方法及效果。方法：对40例房性心动过速患者应用CARTO标测心房,构建三维电解剖图,分析房性心动过速的电生理机制。局灶性房速消融最早激动点,大折返性房速消融折返环的关键性峡部。选择利用常规方法行消融的28例患者作为对照组。比较两组消融的成功率、X线曝光时间。结果：38例患者CARTO三维标测系统标测提示为局灶性房性心动过速,最早激动点位于右心房35例,其中冠状静脉窦口8例（20%）、间隔部10例（25%）、侧壁8例（20%）、上腔静脉口附近4例（10%）、后壁4例（10%）,1例患者（2.5%）有3种类型房速（分别为间隔部、上腔静脉口的局灶房速和三尖瓣峡部依赖的大折返房速）。位于左心房的局灶房速3例,分别位于右上肺静脉口（2.5%）、左上肺静脉口（2.5%）及左心耳（2.5%）。2例患者为大折返房速（5%）,1例为三尖瓣峡部依赖性,1例为围绕界嵴的大折返房速。均消融成功（100%）,随访4～16个月,均无复发。常规消融组成功率为89.3%（P〈0.05）。CARTO组X线曝光时间比常规组明显缩短,分别为（13.8±5.5）min和（30.4±12.9）min,差异有统计学意义（P〈0.05）。结论：应用CARTO标测房性心动过速,对分析房性心动过速的机制准确快速,能有效指导射频消融。     

Suppression of Storms of Ventricular Tachycardia by Epicardial Ablation of Isolated Delayed Potential in Noncompaction Cardiomyopathy

A 65‐year‐old recipient of an implantable cardioverter defibrillator suffering from ventricular noncompaction developed storms of ventricular tachycardia (VT). Epicardial voltage mapping revealed the presence of a large low‐voltage area in the left ventricular apical and inferoposterior wall, and isolated delayed potential was recorded over 1.5 cm in the posterior border between low and normal myocardial voltage. Pacemapping at the delayed potential recording site produced two different QRS depending on pacing output strength, and these two QRS morphologies were similar to clinically documented VTs. During one of the VTs, a mid‐diastolic potential was recorded from the site with the delayed potential, and rapid pacing produced concealed entrainment. After epicardial radiofrequency ablation of the isolated delayed potential, VTs were noninducible and the VT storm was suppressed.     

Radiofrequency Catheter Ablation of Ventricular Tachycardia Guided by Nonsurgical Epicardial Mapping in Chronic Chagasic Heart Disease

We report a case of a 63-year-old women with Chagas'disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.     

Epicardial Macroreentrant Ventricular Tachycardia Associated with a Left Ventricular Aneurysm

A 62‐year‐old man with severe coronary artery disease and a left ventricular aneurysm underwent catheter ablation of ventricular tachycardia (VT) with right bundle branch block QRS morphology. Endocardial bipolar voltage mapping with standard threshold settings demonstrated no low‐voltage areas within the aneurysm. Catheter ablation of the epicardial surface of the aneurysm eliminated the VT. Endocardial bipolar voltage mapping with any other settings could not predict the site of the epicardial arrhythmogenic substrate whereas endocardial unipolar voltage mapping could. Endocardial unipolar voltage mapping may be helpful for predicting epicardial arrhythmogenic substrates. (PACE 2012; 35:e13–e16)     

Why Is Catheter Ablation Less Successful than Surgery for Treating Ventricular Tachycardia that Results from Coronary Artery Disease?

Nearly 80% of patients with coronary artery disease who have map-directed surgery for control of ventricular tachycardias require no drug therapy to prevent recurrences, while fewer than 50% of patients undergoing catheter ablation have similar outcomes. Catheter ablation will fail if arrbythmogenic sites are incompletely ablated by lesions that are too small or too far away from the reentrant pathway or if all arrbythmogenic sites are not identified. The underlying assumptions used to guide site selection are that: (a) ventricular tachycardias arise from reentrant mechanisms; (b) monomorphic ventricular tachycardias with similar QRS morphologies arise from the same pathway; (c) the ventricular tachycardia initiated during the procedure represents the patient's spontaneous arrhythmia; (d) the endocardial site that should be ablated can be identified from cardiac activation maps produced during induced ventricular tachycardia or from ancillary techniques; and (e) the patient has only one or two reentrant pathways. Relying on incorrect assumptions may account for the difference in success rates. Patients may have similar appearing ventricular tachycardias that arise from different pathways, and the entire thin layer of viable tissue between the infarct and the endocardium may contain many reentrant pathways. Some ventricular tachycardias may arise from the myocardium away from the endocardium, while others may arise from the epicardium. Small lesions may not be large enough to eliminate all possible reentrant pathways. Catheter ablation may be less successful because the lesions are inadequate, the assumptions guiding the selection of arrhythmogenic tissue are incorrect, or all arrhythmogenic sites are not identified. The primary reason catheter ablation is less successful than surgery in the treatment of ventricular tachycardias is that catheter ablation does not ablate as much tissue as is removed by surgery. The success rate of catheter ablation probably can be improved if the amount of tissue ablated is increased.     

Dual Epicardial Ventricular Tachycardia: A Tale of Two VTs

A young female with isolated ventricular noncompaction and acute myocarditis presented with incessant dual epicardial ventricular tachycardia consisting of a manifest reentrant circuit and a shorter cycle length concealed circuit. A single radiofrequency terminated both tachycardias. (PACE 2012; 35:e1–e5)     

Thorax Percutaneous Approach for Epicardial Ventricular Ablation in a Patient with Electrical Storm

Subxiphoid puncture is considered the standard approach for epicardial ablation of ventricular arrhythmia, but in some cases this access is impracticable due to the patient's anatomy. We describe the case of a patient with electrical storm and abnormal subdiaphragmatic anatomy that precluded the usual subxiphoid approach. In this patient the pericardial space was gained through a direct thorax puncture at the fifth intercostals space close to the mammary line. The tools and technique utilized in this case were similar to what is usually used for traditional subxiphoid puncture. The thorax percutaneous puncture was successfully carried out without complication.     

Catheter Ablation for Control of Ventricular Tachycardia: A Report of the Percutaneous Cardiac Mapping and Ablation Registry

Catheter ablation of ventricular tachycardia is a procedure of last resort in critically ill patients. The Percutaneous Cardiac Mapping and Ablation Registry was able to collect data on 88 patients undergoing ablation of ventricular tachycardia foci. The mean following interval for the group was 10 ± 8 months. Results were divided into three categories: Group I patients remained asymptomatic and were on no antiarrhythmic medications (33%); Group II remained asymptomatic and took antiarrhythmic agents (38%): Group III patients were considered unsuccessful and consisted of 29 percent of the total. More than one-third of patients received two shocks; the remainder received from one to five shocks. Overall mortality included four procedure-related deaths and total follow-up mortality was 25 percent. Catheter ablation for ventricular tachycardia should he undertaken only in highly specialized centers with an expert and experienced electrophysiologist with immediate surgical back-up available.     

Catheter Ablation of Ventricular Tachycardia Following Myocardial Infarction Using Three-Dimensional Electroanatomical Mapping

KAUTZER, J., et al.: Catheter Ablation of Ventricular Tachycardia Following Myocardial Infarction Using Three-Dimensional Electroanatomical Mapping. One challenge encountered during catheter ablation of postinfarction ventricular tachycardia (VT) is the inducibility of multiple VT morphologies associated with variable hemodynamic instability. The clinical usefulness and safety of a three-dimensional electroanatomical mapping in guiding radiofrequency (RF) catheter ablation of VT, used in parallel with a multichannel recording system, was studied in 28 men (mean age =   63.8 ± 10.6 years   , mean left ventricular ejection   fraction = 28%± 9%   ). Three-dimensional voltage maps of the left ventricle were obtained in sinus rhythm with annotation of areas of fractionated or late potentials, zones of slow conduction and/or dense scar with no pacing capture at 10 mA. RF lesions were created either in sinus rhythm or during hemodynamically stable VT within reconstructed critical zones of the circuit. A total of 82 VTs were induced   (mean = 2.9 ± 1.0/patient)   . Hemodynamically unstable clinical VTs were induced in 5 patients, and clinical or nonclinical unstable VT in 14. Clinical VT was rendered noninducible in 24/28 (85.7%) patients, and monomorphic VT was eliminated in 16/28 (57.1%) patients. The mean procedural time was   258 ± 82   minutes, and fluoroscopic exposure   13.5 ± 8.8 minutes   . During a mean follow-up period of   10.6 ± 6.4 months   , catheter ablation was repeated in 6 patients for VT recurrences. No significant complications occurred except for a transient cerebral ischemic attack in one patient. In conclusion, electroanatomical mapping assisted the successful and safe catheter ablation of both mappable and nonmappable VTs in a significant proportion of patients after myocardial infarction. (PACE 2003; 26[Pt. II]:342–347)     

Development of an Interactive Computer-Guided Method for Radiofrequency Catheter Ablation of Ventricular Tachycardia

The purpose of this study was to develop a simple computer-guided approach to localizing ventricular tachycardias during ventricular mapping. Six patients with sustained monomorphic ventricular tachycardia were connected to a 32-lead computer body surface mapping system. Isoarea maps of induced ventricular tachycardia were recorded. Then a pacing probe was placed in either the right or left ventricle, and maps were generated from a variety of sites. Differences between ventricular tachycardia and pace map maxima X,Y coordinates were utilized to guide catheter manipulation and localization. In 6 of 6 patients (100%) this method appeared to provide a systematic approach to ventricular tachycardia localization. Computer-generated correlations as well as the X,Y coordinates of the QRS isoarea maxima were used to determine proximity to the ventricular tachycardia foci and direct catheter manipulation. In the next three patients this method was applied prospectively to help guide catheter manipulation during ventricular tachycardia (two right ventricular outflow tract tachycardias, and one left ventricular tachycardia). After a mean of 4.0 ± 1.7 radiofrequency applications, ventricular tachycardia was no longer inducible, and at 7 ± 0 months follow-up there have been no arrhythmia recurrences. We conclude that online computerized body surface mapping can assist in localizing ventricular tachycardia. Differences in maxima during pace maps and in-situ ventricular tachycardias can help with catheter manipulation as well as with more precise identification of focal tachycardias. This technique appears to hold the promise of a simple computer-guided method that may facilitate radiofrequency catheter ablation.     

Contact versus Noncontact Mapping for Ablation of Ventricular Tachycardia in Patients with Previous Myocardial Infarction

Introduction: The aim of this study was to compare contact versus noncontact mapping for radiofrequency (RF) ablation of any sustained post-myocardial infarction (MI) ventricular tachycardia (VT).
Methods: Forty patients with tolerated VT post-MI were randomized to RF ablation with contact (group 1) or noncontact (group 2) mapping systems. In both groups ablation of tolerated VT was guided by VT activation map confirmed by concealed entrainment. When untolerated VTs were induced, ablation was performed in group 1 according to pace mapping starting from the scar border zone and in group 2 according to the VT activation map confirmed by pace mapping.
Results: No differences were seen between the groups in terms of acute success rate of clinical VT ablation (95% vs 100%, respectively; P = ns) and in the noninducibility of any VT at the end of the procedure (55% vs 85%, respectively; P = 0.08). Moreover, untolerated VTs were eliminated in 30% of group 1 versus 83.3% of group 2 patients (P < 0.05). The mean total procedural and fluoroscopy times were 236.4 ± 42.7 and 29.0 ± 7.8 minutes in group 1 and 144.5 ± 50.8 and 23.4 ± 5.8 minutes in group 2 (P < 0.001 and < 0.05, respectively). At a mean follow-up of 15.2 ± 6.7 months no differences were seen in VT recurrences between groups, but noninducibility at the end of the procedure was predictive of freedom from recurrences (P < 0.001).
Conclusion: Both systems are useful for ablation of tolerated VT. Noncontact mapping is more effective for ablation of untolerated VT and allows the reduction of procedural and fluoroscopy times. Noninducibility at the end of the procedure seems predictive of freedom from recurrences during follow-up.     

三维标测系统指导下的射频消融特发性室速护理

目的总结在三维标测系统Carto3指导下射频消融治疗特发性室速患者的护理方法。方法对2010年11月-2011年10月收治的62例特发性室速患者,采用Carto3系统进行心室标测和消融治疗,并予以周全细致的护理。结果本组61例患者顺利完成射频消融术,1例因诱发室颤后停止手术。术后随访6个月,3例出现既往相同形态室速,其余58例症状较前均有不同程度的缓解,未发生明显心动过速,手术成功率为93．55％。结论Carto3系统指导下的特发性室速射频治疗安全、高效,可减少射线透视量,恰当细致的护理配合是手术获得成功的基础与保障。     

Identification and Ablation of Macroreentrant Ventricular Tachycardia with the CARTO Electroanatomical Mapping System

Monomorphic ventricular tachycardias associated with regions of scar are most commonly due to reentry. Catheter based techniques have recently been described for mapping of reentry circuits. Fluoroscopic methods have obvious limitations when attempting to map large ventricular reentry circuit and localize target-sites of radiofrequency ablation. Three-dimensional right ventricular endocardial mapping was performed in a 38-year-old patient with ventricular tachycardia 28 years after surgical correction of tetralogy of Fallot by using the CARTO electroanatomical system. The map of electrogram voltage showed low amplitude electrograms over the anterior wall of the right ventricle extending into the right ventricular outflow tract, consistent with the location of the ventriculotomy scar. Recording of local activation time was combined with entrainment mapping to define the macroreentrant circuit during ventricular tachycardia. Since the activation propagated through a broad path around the right ventriculotomy scar, ablation was performed by creating a line of block, which was facilitated by tagging of the lesion sites on the endocardial activation map. Large ventricular reentry circuits can be identified and interrupted by creation of a line of block to interrupt a broad path. A practical approach to mapping combining analysis of electrogram voltage, activation sequence, and entrainment is presented.     

Catheter Ablation of Ventricular Tachycardia in Patients with Right Ventricular Dysplasia: Identification of Target Sites by Entrainment Mapping Techniques

Objective: To identify target sites for radiofrequency ablation of ventricular tachycardia (VT) by entrainment mapping techniques in patients with arrhythmogenic right ventricular dysplasia. Methods: Entrainment mapping and radiofrequency ablation of eight VTs was performed in seven patients. Radiofrequency ablation was applied at 31 reentry circuits sites that were classified based on findings during entrainment. Results: By entrainment criteria the 31 sites were classified as: exit sites (n = 12), proximal sites (n = 6), and outer loop sites (n = 13). Radiofrequency current application terminated VT at 7 of 31 sites: 2 of 12 exit sites (17%), 4 of 6 proximal sites (67%), and 1 of 13 outer loop sites (8%). Conclusion: Radiofrequency ablation terminated VTs most often at sites proximal to the exit as opposed to outer loop sites and exit sites (P = 0.05). The critical isthmus for ablation of VT in right ventricular dysplasia often may be distant to the exit.     

Use of Cardioplegia to Guide Alcohol Ablation for Incessant Ventricular Tachycardia

Incessant scar‐related reentrant ventricular tachycardia is an important cause of morbidity and mortality. In patients not amenable to emergent radiofrequency catheter ablation, selective transcoronary alcohol ablation has been successfully performed. In our case study, we introduce the novel use of cardioplegia as a mapping technique for identification of the critical ventricular tachycardia isthmus to guide efficient transcoronary alcohol ablation and prevent unnecessary myocardial damage.     

Surgical Catheter Ablation of Ventricular Tachycardia Using Left Thoracotomy in a Patient with Hindered Access to the Left Ventricle

We report the case of a patient presenting with incessant monomorphic ventricular tachycardia resistant to antiarrhythmic drugs, and in whom usual percutaneous vascular or pericardial access to the left ventricle was hindered by mechanical aortic and mitral prosthetic valves. Because an epicardial location was suspected by electrocardiogram features and because access to the target area through the coronary sinus was not possible, we decided to perform a surgically based radiofrequency (RF) ablation. Catheter mapping of the epicardial surface through surgical left lateral thoracotomy in the operating room confirmed the epicardial location of the arrhythmogenic substrate and allowed successful RF ablation of the clinically incessant tachycardia. Combined surgical and electrophysiological approach should therefore be performed when RF ablation is needed in case of unadvisable, difficult, or failed nonsurgical percutaneous access.     

Catheter Ablation of Electrical Storm Due to Monomorphic Ventricular Tachycardia in Patients with Nonischemic Cardiomyopathy: Acute Results and Its Effect on Long‐Term Survival

Background: Electrical storm due to recurrent ventricular tachycardia (VT) in patients with implantable cardioverter defibrillator (ICD) can adversely affect their long‐term survival. This study evaluates the efficiency of the radiofrequency catheter ablation of electrical storm due to monomorphic VT in patients with idiopathic dilated cardiomyopathy (DCM) and assesses its long‐term effects on survival. Methods and Results: Between April 2004 and October 2008, 13 consecutive patients (nine men, mean age 56.8 ± 17.8 years) with DCM and electrical storm due to monomorphic VT who had ICD underwent 17 catheter ablation procedures, including four epicardial, at our center. Acute complete success was defined as the lack of inducibility of any VT at the end of procedure during programmed right ventricular stimulation and was achieved in eight patients (61.5%). During a median follow‐up of 23 months (range 3–63 months) nine patients (69%) were alive and eight patients (61.5%) were free from VT recurrence. Among those with acute complete (n = 8) and partial (n = 5) success, seven patients (87.5%) and one patient (20%) were free from any VT recurrence and ICD therapy, respectively (P = 0.025). Among those with acute complete and partial success, seven patients (87.5%) and two patients (40%) were alive, respectively (Mantel‐Cox test P = 0.082). Among those who had an initially failed endocardial ablation (n = 8), four underwent further epicardial ablation that was completely successful in three patients (75%). Conclusion: Catheter ablation in patients with DCM and electrical storm due to monomorphic VT who had an ICD prevents further VT recurrence in 61.5% of the patients. Complete successful catheter ablation may play a protective role and was associated with reduced mortality during the follow‐up period. More aggressive ablation strategies in patients with initially failed endocardial ablation might improve the long‐term survival of these patients; however, further studies are needed to clarify this issue. (PACE 2010; 33:1504–1509)