Outcome of ventricular tachycardia catheter ablation in ischemic heart disease patients using a high-density mapping substrate-based approach: A prospective cohort study

Introduction and objectiveRadiofrequency catheter ablation (RCA) for ventricular tachycardia (VT) in patients with ischemic heart disease (IHD) is associated with a reduced risk of VT storm and implantable cardioverter defibrillator (ICD) shocks. We aim to report the outcome after a single RCA procedure for VT in patients with IHD using a high-density substrate-based approach.MethodsWe conducted a prospective, observational, single-center and single-arm study involving patients with IHD, referred for RCA procedure for VT using high-density mapping catheters. Substrate mapping was performed in all patients. Procedural endpoints were VT non-inducibility and local abnormal ventricular activities (LAVAs) elimination. The primary end point was survival free from appropriate ICD shocks and secondary end points included VT storm and all-cause mortality.ResultsSixty-four consecutive patients were included (68±9 years, 95% male, mean ejection fraction 33±11%, 39% VT storms, and 69% appropriate ICD shocks). LAVAs were identified in all patients and VT inducibility was found in 83%. LAVA elimination and non-inducibility were achieved in 93.8% and 60%, respectively. After a mean follow-up of 25±18 months, 90% and 85% of patients are free from appropriate ICD shocks at one and two years, respectively. The proportion of patients experiencing VT storm decreased from 39% to 1.6%. Overall survival was 89% and 84% at one and two years, respectively.ConclusionsRCA of VT in IHD using a high-density mapping substrate-based approach resulted in a steady freedom of ICD shocks and VT storm.     

Substrate-modification using electroanatomical mapping in sinus rhythm to treat ventricular tachycardia in patients with ischemic cardiomyopathy

Summary The treatment especially of frequent ischemic VT remains a challenge for medical and catheter ablation procedures. We evaluated the efficacy of a substrate-based procedure to eliminate clinical VTs in this patient collective.Methods In 25 consecutive patients (ejection fraction 37±12%) with frequent symptomatic medically refractory ischemic VT (with recurrent ICD-shocks), left ventricular anatomic scar mapping (Biosense Webster CARTO™) was performed in order to modify the underlying myocardial substrate. Scar tissue was identified as having bipolar voltages <0.5 mV. Prior to the procedure an electrophysiological study (EPS) to determine number and morphology of inducible VTs was performed. Linear ablation procedures (8 mm tip, 70 Watts, 70 °C) were based on the findings of scar areas and proximity to anatomic obstacles. Correct location of ablation was documented by similarity of the morphology during pace-mapping. Follow-up included clinical evaluation, ICD holter interrogation plus holter ECG recording.Results The clinical VT was eliminated by linear catheter ablation in 23/25 patients (92%) (failure due to unstable catheter position during transaortic approach in 1 and epicardial origin of VT in 1). In 16/23 patients (70%) complete success could be produced with no VT inducible after substrate modification (1.7±1.0 lines per patient). In 7 patients (30%) only partial success was documented with further VTs inducible after ablation. No procedure-related complications occurred. During follow- up (10±4 months) 4 patients (16%) had occurrences of new VTs documented on ICD holter (3 patients with initially partial success and 1 with initial complete success) differing in cycle length and morphology from the clinical VT. Comparing patients with complete to those with partial success, there was a statistically significant difference of 93 vs. 48% freedom of arrhythmia (p=0.03). No difference in regard to baseline characteristics existed in these two patient subgroups.Conclusions Ablation of frequent VTs in patients with ischemic cardiomyopathy can be safely performed using electro-anatomic scar mapping with a high procedural success of 90%. Based on the morphological findings, linear ablation can suppress inducibility of all VTs in 70% of patients with high mid-term efficacy. In patients with only partial ablation success, non-clinical VTs often occur early during follow-up (50%).     

Impact of different activation wavefronts on ischemic myocardial scar electrophysiological properties during high-density ventricular tachycardia mapping and ablation

Introduction

Scar-related ventricular tachycardia (VT) usually results from an underlying reentrant circuit facilitated by anatomical and functional barriers. The later are sensitive to the direction of ventricular activation wavefronts. We aim to evaluate the impact of different ventricular activation wavefronts on the functional electrophysiological properties of myocardial tissue.

Methods

Patients with ischemic heart disease referred for VT ablation underwent high-density mapping using Carto®3 (Biosense Webster). Maps were generated during sinus rhythm, right and left ventricular pacing, and analyzed using a new late potential map software, which allows to assess local conduction velocities and facilitates the delineation of intra-scar conduction corridors (ISCC); and for all stable VTs.

Results

In 16 patients, 31 high-resolution substrate maps from different ventricular activation wavefronts and 7 VT activation maps were obtained. Local abnormal ventricular activities (LAVAs) were found in VT isthmus, but also in noncritical areas. The VT isthmus was localized in areas of LAVAs overlapping surface between the different activation wavefronts. The deceleration zone location differed depending on activation wavefronts. Sixty-six percent of ISCCs were similarly identified in all activating wavefronts, but the one acting as VT isthmus was simultaneously identified in all activation wavefronts in all cases.

Conclusion

Functional based substrate mapping may improve the specificity to localize the most arrhythmogenic regions within the scar, making the use of different activation wavefronts unnecessary in most cases.     

室性心动过速的基质标测与消融

目的 探讨使用Carto三维系统标测致心律失常性右心室心肌病(ARVD/C)室性心律失常的基质来指导导管消融的安全性和有效性.方法 自2007年7月至2008年4月,北京大学第一医院心内科连续收治4例ARVD/C患者,年龄28～53岁,男性3例,女性1例,其中1例患者有直系亲属猝死家族史,发作性室性早搏/室性心动过速(VT)病史3个月至24年.使用Carto三维系统进行电解剖电压标测,局部电压低于1.5 mV的区域判断为病变心肌,低于0.5 mV的区域为瘢痕区,结合传统的激动顺序标测、起搏标测、拖带标测和心室内碎裂电位,识别病变心肌范围和心动过速折返路径以指导消融.结果 4例患者电生理检查共诱发出7种形态的左束支阻滞形、VT,电解剖电压标测的低电压区主要位于右心室流人道的基底部和偏间隔部,在病变心肌与正常心肌交界区和/或环绕病变心肌的最早激动处做线性消融,4例患者均获消融即刻成功,无并发症.4例患者消融术后随访3个月至1年,有1例出现复发,口服胺碘酮控制,至今无晕厥和猝死.结论 ARVD/C的VT标测与消融安全可靠,应用三维系统进行电解剖电压标测与传统的心电标测方式相结合,可更精确判断ARVD/C的室性心律失常基质和有效提高消融成功率.     

CARTO标测指导心肌梗死后室性心动过速的射频消融

心肌梗死 (MI)后室性心动过速 (VT)的基质存在解剖上的复杂性并且血液动力学常常是不稳定的 ,因此射频导管消融的成功率是有限的。本研究的目的是运用电解剖标测 (CARTO)指导VT的射频消融 ,以便弄清折返环和梗死区的关键峡部 ,此可能增加临床消融的效率。 19例MI的病人 (年龄 6 6± 7岁 ,其中男性 17例 )因VT拟作 2 0次消融 [17例在服用抗心律失常药 ,7例已安装埋藏式心脏转复除颤器 (ICD) ]。所有病例均反复发作临床型VT(周期为 42 3± 87ms)。在VT时或窦律 /右室起搏 (SR/RVP)行左室CARTO标测。对 13例 14次血液动力学稳定的VT实施标测 ,包括 2例无休止性慢VT。仅 8例临床性VT ,在心动过速时完成了整个左室的重建 ,另 6例因反复机械损伤MI区内关键性峡部 ,使临床型VT不再诱发。 12例在SR/RVP时完成左室标测 ,包括 6例关键性峡部损伤及 6例血液动力学不稳定者。在 8例CARTO标测的VT中 ,有 3例呈现典型的“8字”型折返环 ,2例沿二尖瓣 (MA)激动心室。在 8例VT中 ,于关键性峡部放电消融 ,其中 6例VT终止 ,平均放电 2次 ;然后行线性消融连接两个疤痕区域或连接疤痕与MA环 ,平均放电 16次。在SR/RVP时标测 ,可见 1个或多个疤痕区域 ,4例在诱发VT时放电 ,均终止了VT ;另 8例因极不稳定的血液动力学或机械损?     

Rescue ablation of electrical storm in patients with ischemic cardiomyopathy: a potential-guided ablation approach by modifying substrate of intractable, unmappable ventricular tachycardias.

OBJECTIVES: The purpose of this study was to evaluate a substrate-modifying, primarily potential-guided catheter ablation approach as a bailout therapy in patients with complex myocardial infarction and electrical storms due to ventricular tachycardias (VTs). BACKGROUND: Management of electrical storm is a domain of medical treatment. A definite trigger or delineated scar has been characterized as a requirement for substrate-orientated ablation of intractable unmappable ventricular tachyarrhythmias but can be absent, as shown in the presented cases. METHODS: Five patients who presented with ischemic cardiomyopathy and severe reduced left ventricular ejection fraction also suffered from multiple types of unstable VTs that deteriorated into drug-refractory electrical storm. Patients had 96 to 580 VT episodes requiring therapy with an implantable cardioverter-defibrillator (ICD) and received 3 to 310 shock deliveries prior to ablation. Treatment with beta-blockers, amiodarone, class IB antiarrhythmic drugs, deep sedation, and overdrive pacing and/or cardioversion of incessant VTs failed to stabilize the electrical storm but enabled left ventricular electroanatomic voltage mapping. A simplified substrate modification was performed by ablation of delayed fractionated potentials in areas identified by pace mapping, matching three to eight documented types of VTs per patient in complex scar areas. RESULTS: All patients could be stabilized after ablation. During 12 to 30 months of follow-up, three patients remained free of any VT episode requiring ICD treatment, and two patients had <1 VT episode per month. CONCLUSIONS: The cases presented demonstrate that rescue VT ablation of drug-refractory electrical storm is possible by a substrate-orientated ablation approach even in patients with complex chronic infarction and various VTs.     

Feasibility of the transseptal approach for fast and unstable left ventricular tachycardia mapping and ablation with a non-contact mapping system

Background Radiofrequency ablation of fast and unstable left ventricular tachycardia (VT) usually requires non-contact mapping. The procedure is usually performed by a retrograde-transaortic route, requiring a double femoral artery puncture, for the 9F multielectrode catheter and the 7F ablation catheter which are advanced through the aorta and aortic valve into the left ventricle (LV). Reported limitations of the procedure are due to the stiffness of the balloon catheter, particularly in patients with tortuous peripheral arteries, atherosclerotic aorta, or with aortic stenosis. The aim of our study was to test the feasibility and assess the safety of a transseptal approach for left VT non-contact mapping and ablation.Materials and methods Ten patients with multiple cardiac defibrillator shocks because of fast and unstable VT were selected for non-contact mapping and ablation. After a double transseptal puncture the multielectrode catheter (Ensite Array™, St. Jude Medical) was advanced through a standard 10F introducer to a stable position in the LV apex over a 260 cm length 0.035 J-tip guidewire. The ablation catheter (Celsius™ Thermo-cool, Biosense Webster) was then inserted through the second 8F introducer. Twenty-five monomorphic sustained ventricular tachycardia were induced and ablated at the level of the diastolic pathway or exit point revealed by unipolar isopotential mapping. The total procedural and fluoroscopy times were 209 ± 32 min and 28.5 ± 9.27 min, respectively, which were comparable to those described with the traditional retrograde-transaortic approach. No major complication related with the transseptal approach were reported.Conclusion A transseptal approach can be a feasible and effective alternative approach for mapping and ablation of fast and unstable left VT with a non-contact mapping system.     

The Origin of Epicardial Ventricular Tachycardia Revealed by Entrainment From a Permanent Epicardial Left Ventricular Pacing Lead

Entrainment From Left Ventricular Pacing Lead. Recognizing ventricular tachycardias (VTs) that require epicardial ablation is desirable, but challenging when prior surgery prevents percutaneous epicardial mapping. This patient had cardiomyopathy, prior cardiac surgery, and VT that failed endocardial ablation. Observing that the Bi‐V implantable cardioverter defibrillator (ICD), left ventricular (LV) lead was epicardial to the area of infarct scar, it was used to pace during VT. Entrainment with concealed fusion with long stimulus to QRS interval, consistent with an epicardial VT circuit, was observed. Surgical cryoablation targeting the area around the LV lead eliminated VT. Thus pacing maneuvers from permanent epicardial leads can occasionally help identify an epicardial VT origin. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1293‐1295, November 2010)     

Human histopathology of electroanatomic mapping after cooled-tip radiofrequency ablation to treat ventricular tachycardia in remote myocardial infarction

INTRODUCTION: Catheter ablation of ventricular tachycardia (VT) in remote myocardial infarction (MI) often requires excessive mapping procedures. Documentation of the electrical substrate via electrogram amplitude may help to identify regions of altered myocardium resembling exit areas of reentrant VTs. METHODS AND RESULTS: A patient with multiple symptomatic monomorphic VTs (biventricular ICD, remote MI) underwent electroanatomic substrate mapping (CARTOtrade mark) for VT ablation. Regions of scar (bipolar electrogram amplitudes or=1.5 mV), and "altered" myocardium (0.5-1.5 mV) were identified. Ablation was directed to regions with "altered" myocardium based on pace map correlation. After ablation the clinical VT did not reoccur. The patient died due to worsening of heart failure 7 days afterward. During postmortal evaluation specified sites of electroanatomic mapping were correlated to histopathological findings. Annotated scar areas were documented to consist of areas with massive fibrosis (>or=80% of mural composition). Ablations were found to span through regions with intermediate fibrosis (21-79%) mapped as "altered" myocardium. Ablation produced transmural coagulation necrosis of mesh-like fibrotic tissue with interspersed remnants of myocardial cells up to a maximum depth of 7.0 mm. Subendocardial intramural bleedings were universal findings 7 days after ablation. CONCLUSIONS: Electroanatomic substrate mapping for VT ablation sufficiently identified regions of scar and normal myocardium. Regions with bipolar electrogram amplitudes between 0.5 and 1.5 mV were found to correlate to areas of "intermediate" fibrosis (21-79%) with only remnant strands of myocardial cells and were identified as target region for ablation. Cooled-tip endocardial radiofrequency ablation lead to transmural coagulation necrosis up to a depth of 7.0 mm.     

Relationship between successful ablation sites and the scar border zone defined by substrate mapping for ventricular tachycardia post-myocardial infarction

INTRODUCTION: It is unknown if identification of scar border zones by electroanatomical mapping correlates with successful ablation sites determined from mapping during ventricular tachycardia (VT) post-myocardial infarction (MI). We sought to assess the relationship between successful ablation sites of hemodynamically stable post-MI VTs determined by mapping during VT with the scar border zone defined in sinus rhythm. METHODS AND RESULTS: Forty-six patients presenting with hemodynamically stable, mappable monomorphic VT post-MI and who had at least one such VT successfully ablated were prospectively included in the study. In each patient, VT was ablated by targeting regions during VT that exhibited early activation, +/- isolated mid-diastolic potentials, and concealed entrainment suggesting a critical isthmus site. Prior to ablation, a detailed sinus-rhythm CARTO voltage map of the left ventricle was obtained. A voltage <0.5 mV defined dense scar. Successful VT ablation sites were registered on the sinus voltage map to assess their relationship to the scar border zone. Of the 86 VTs, 68% were successfully ablated at sites in the endocardial border zone. The remaining VTs had ablation sites within the scar in (18%), in normal myocardium (4%), and on the epicardial surface (10%). There were no significant differences in VT recurrence amongst the different groups. CONCLUSION: Successful ablation sites of hemodynamically stable, monomorphic VTs post-MI are often located in the scar border zone as defined by substrate voltage mapping. However, in a sizable minority, ablation sites are located within endocardial scar, epicardially, and even in normal myocardium.     

致心律失常性右室心肌病的CARTO系统电生理基质标测和射频导管消融

目的应用CARTO系统对致心律失常性右室心肌病(ARVC)患者进行电解剖标测并指导射频消融治疗其室性心动过速(简称室速)。方法入选伴有室速反复发作的25例ARVC患者,年龄36±12岁,男性17例,有家族成员35岁以下早发猝死史3例。术前行常规心电图、心室晚电位、心脏B超检查。在窦性心律或/和心动过速时,电解剖标测三维重建右室。术中6例同时行右室造影检查。根据双极电图电压高低确定疤痕区、正常心肌和临界边缘区。对于折返性室速,线性消融关键峡部或疤痕区与三尖瓣环之间或两疤痕区间;对于局灶性室速,点消融局部最早激动区域。结果 20%(5/25)体表心电图发现前壁或下壁导联Epsilon波,心室晚电位阳性占88%(21/25),心脏B超发现右室不同程度的局部或整体扩张,56%(14/25)可见局部囊袋状向外膨出。所有患者均出现1～5(2±1)种左束支阻滞型室速,其中5例合并频发室性早搏,1例伴心房扑动,1例伴左后间隔旁道。即时消融成功率为72%(18/25)。随访14±10(4～36)个月,原消融成功的5例室速复发。1例消融失败伴晕厥史的患者植入ICD治疗。无手术相关并发症和死亡发生。结论应用CARTO系统电解剖标测可安全有效指导射频消融治疗ARVC患者的室速,有相对较高的失败和复发率。CARTO系统标测的电压图,参考术前心电图、心脏B超及右室造影可了解病变心肌的分布范围,对初步确定室速的病理基质有帮助。     

Substrate-modification using electroanatomical mapping in sinus rhythm to treat ventricular tachycardia in patients with ischemic cardiomyopathy

The treatment especially of frequent ischemic VT remains a challenge for medical and catheter ablation procedures. We evaluated the efficacy of a substrate-based procedure to eliminate clinical VTs in this patient collective.

Methods  

In 25 consecutive patients (ejection fraction 37±12%) with frequent symptomatic medically refractory ischemic VT (with recurrent ICD-shocks), left ventricular anatomic scar mapping (Biosense Webster CARTO™) was performed in order to modify the underlying myocardial substrate. Scar tissue was identified as having bipolar voltages <0.5 mv.=" prior=" to=" the=" procedure=" an=" electrophysiological=" study=" (eps)=" to=" determine=" number=" and=" morphology=" of=" inducible=" vts=" was=" performed.=" linear=" ablation=" procedures=" (8=" mm=" tip,=" 70=" watts,=" 70=" °c)=" were=" based=" on=" the=" findings=" of=" scar=" areas=" and=" proximity=" to=" anatomic=" obstacles.=" correct=" location=" of=" ablation=" was=" documented=" by=" similarity=" of=" the=" morphology=" during=" pace-mapping.=" follow-up=" included=" clinical=" evaluation,=" icd=" holter=" interrogation=" plus=" holter=" ecg=">     

Impact of catheter ablation for atrial fibrillation in patients with heart failure and left ventricular systolic dysfunction

Introduction and AimsCatheter ablation has been shown to improve left ventricular (LV) ejection fraction (LVEF) in patients with atrial fibrillation (AF) and heart failure (HF). Our aim was to assess the impact of AF ablation on the outcome of patients with HF and LV systolic dysfunction.MethodsWe performed a retrospective observational cohort study of all patients with HF and LVEF <50% and with no apparent cause for systolic dysfunction other than AF who underwent catheter ablation in a tertiary referral center between July 2016 and November 2018. The primary endpoint was a ≥5% improvement in LVEF. Secondary endpoints included improvement in New York Heart Association (NYHA) class and reduction in LV end-diastolic diameter (LVEDD) and left atrial diameter (LAD).ResultsOf 153 patients who underwent AF ablation in this period, 22 (77% male, median age 61 [IQR 54-64] years) fulfilled the inclusion criteria. Median follow-up was 11.1 months (IQR 6.1-19.0). After ablation, median LVEF increased from 40% (IQR 33-41) to 58% (IQR 55-62) (p<0.01), mean NYHA class improved from 2.35±0.49 to 1.3±0.47 (p<0.001), and median LAD and LVEDD decreased from 48.0 (IQR 43.5-51.5) mm to 44 (IQR 40-49) mm (p<0.01) and from 61.0 (IQR 54.0-64.8) mm to 55.0 (52.2-58.0) mm (p<0.01), respectively.ConclusionIn patients with HF and LV systolic dysfunction, AF ablation is associated not only with improved functional status but also with favorable structural remodeling, including improvement in LVEF and decreases in LAD and LVEDD.     

Epicardial ablation of ventricular tachycardia using a new high-density mapping system

We report the case of a 44-year-old woman who was referred for ablation of recurrent ventricular tachycardia (VT) in the setting of dilated cardiomyopathy secondary to myocarditis. The ECG displayed a right bundle branch block morphology and superior axis in the frontal plane, associated with a pseudo delta wave in the precordial leads that suggested an epicardial origin.Cardiac magnetic resonance performed prior to the procedure showed late gadolinium enhancement at the lateral wall of the left ventricle (LV) and excluded subendocardial fibrosis in either ventricle. This information was crucial and influenced the ablation strategy, identifying the target area as exclusively epicardial, thus avoiding unnecessary mapping of the endocardial surface of the LV.Epicardial activation mapping and ablation during VT were performed using the Orion® high-density catheter (Boston Scientific Inc.) and the Rhythmia® mapping system (Boston Scientific Inc.). Applications near the exit site immediately terminated the tachycardia, which was no longer inducible.One year after the procedure the patient was still in sinus rhythm with no episodes of VT or non-sustained VT recorded by continuous monitoring via an implanted cardioverter-defibrillator.     

Long-term results after ablation of infarct-related ventricular tachycardia.

OBJECTIVES: The purpose of this study was to assess the long-term effects of ablation of infarct-related ventricular tachycardia (VT) and the subsequent requirement for implantable cardioverter-defibrillator (ICD) therapy. BACKGROUND: The long-term consequences after initially successful catheter ablation of infarct-related VT remain unclear. METHODS: Forty patients who presented with infarct-related VT were studied using noncontact mapping to guide ablation. RESULTS: One hundred forty VTs were mapped using the noncontact mapping system, including 36 (25.7%) clinical VTs. An endocardial exit site was determined in 100% of VT circuits, diastolic endocardial activity in 77 VTs (55%), and complete circuits in 24 VTs (17.1%). Eighty-one VTs (57.9%) were targeted for ablation, of which 67 (82.7% of targeted) were successfully ablated, including 27 clinical VTs (75% of clinical). Documented recurrence of an ablated VT occurred in 7.5% of patients over 36.3 +/- 21.0 months of follow-up. Episodes of new or recurrent, nontargeted VT or ventricular fibrillation (VF) occurred in 37.5% and VT recurrence without documentation of cycle length in 5%. In patients with ICDs, mean shock frequency was reduced from 6.8 +/- 7.3 per month in the year prior to ablation to 0.05 +/- 0.12 per month after ablation, over 24.7 +/- 18.9 months of follow-up (P < .0001). CONCLUSIONS: In patients with infarct-related VT, noncontact mapping-guided VT ablation is associated with a high procedural success rate, and VT recurrence necessitating ICD therapy delivery is significantly reduced. However, only 42.5% of patients remain free from VT/VF 3 years after ablation. Catheter ablation for infarct-related VT is indicated as an adjunctive therapy in patients with symptomatic VT but cannot substitute for ICDs and antiarrhythmic drugs.     

Endocardial and epicardial radiofrequency ablation of ventricular tachycardia associated with dilated cardiomyopathy: the importance of low-voltage scars

OBJECTIVES: The purpose of this study was to evaluate the occurrence, locations, and relationship of ventricular tachycardia (VT) to low-voltage areas in dilated cardiomyopathy (DCM). BACKGROUND: The substrate causing monomorphic VT after infarction is characterized by regions of low-voltage (<1.5 mV) scar on electroanatomic maps. The substrate causing VT associated with DCM is less well defined. METHODS: A total of 28 patients were studied with endocardial (26 patients) and epicardial (8 patients) electroanatomic mapping. The VT circuits were defined by entrainment or pace mapping. RESULTS: Ventricular tachycardia was due to focal VT in 5, bundle-branch re-entry in 2, and myocardial re-entry in 22 patients (both focal and re-entry VTs in 1 patient). All patients with myocardial re-entry had endocardial (20 of 20 patients) and/or epicardial (7 of 7 patients mapped) scar. Most (63%) endocardial scars were adjacent to a valve annulus. Of the 19 VT circuit isthmuses identified, 12 were associated with an endocardial scar and 7 with an epicardial scar. All myocardial re-entrant VTs were abolished in 12 of 22 patients, and inducible VT was modified in 4 patients. During follow-up of 334 +/- 280 days, 54% of patients with myocardial re-entry were free of VT despite frequent episodes before ablation. CONCLUSIONS: The VTs in DCM are most commonly the result of myocardial re-entry associated with scar. Scars are often adjacent to a valve annulus, deep in the endocardium, and can be greater in extent on the epicardium than on the endocardium. The use of epicardial mapping and radiofrequency is likely to improve success.     

Radiofrequency catheter ablation of ventricular tachycardias

Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.     

三维标测指导致心律失常性右心室心肌病室性心动过速的射频消融

目的介绍致心律失常性右心室心肌病（ARVC）室性心动过速（室速）的三维标测方法及其消融策略。方法21例ARVC室速患者,因1—4种抗心律失常药物治疗无效,临床上呈反复发作、无休止发作或植入型心律转复除颤器（ICD）植入后频繁放电治疗,接受导管消融治疗。其中,男性19例,女性2例,平均年龄（32±12）岁。9例患者接受电解剖（Carto）标测,12例患者接受非接触标测（EnSite—Array）。在首先明确病变基质的基础上,通过激动标测、拖带标测及起搏标测,分析心动过速的起源、可能的传导径路及其出口以及它们与病变基质的关系。通常于心动过速的出口处及其周边行局灶消融,术中病变基质周边的延迟激动电位应一并消融。结果21例患者,2例呈无休止发作,1例患者表现为频繁室性早搏及加速性室性自主心律,余18例患者消融中共诱发出34种心动过速。所有心动过速均呈左束支阻滞形,平均心动过速周长为（289±68）ms。16例患者（28种室速）消融治疗即刻成功,3例患者（7种室速）部分成功,2例患者（2种室速）消融失败,即刻消融成功率76．2％。所有患者消融术后继续服用抗心律失常药物。平均随访6～30（1d±7）个月,成功患者中2例复发,其中1例再次消融成功;未达即刻成功的5例患者,经抗心律失常药物治疗后,均无室性心律失常事件发生,其中包括1例消融后植入ICD者。结论三维标测系统可首先明确ARVC患者的病变基质,在此基础上结合激动标测和心内各种电刺激技术,可直观显示心动过速的起源、缓慢传导区出口及折返环路,以此制定消融策略可成功治疗ARVC室速。心动过速起源于心肌深部或ARVC病变进展,是消融失败和复发的常见原因。     

经导管射频消融心律转复除颤器植入后电风暴

目的报道3例心律转复除颤器（ICD）植入后抗心律失常药物治疗无效的室性心律失常电风暴患者经导管射频消融的结果。方法2名男性与1名女性患者,年龄为75、55、37岁,分别患有陈旧性前壁心肌梗死、致心律失常性右心室心肌病、左心室心肌病。均在ICD植入后发生抗心律失常药物治疗无效的电风暴。应用Carto电解剖标测系统引导盐水灌注射频导管标测和消融室性心动过速（VT）。对可标测VT（持续性、血流动力学稳定）行激动和拖带标测;对不可标测VT,则在基质标测的基础上行起搏标测和／或短时间的拖带标测。结果3例患者中共诱发出5种形态的VT,4种血流动力学较稳定VT和1种血流动力学不稳定VT。成功消融了所有形态的VT,抑制了电风暴的急性发作。消融后随访的6、19和36个月中,仅1例患者出现1次ICD放电。结论在电解剖标测的基础上,应用盐水灌注射频导管消融ICD植入后抗心律失常药物治疗无效的电风暴有很好的疗效。     

Ventricular tachycardia in Chagas' disease: a comparison of clinical, angiographic, electrophysiologic and myocardial perfusion disturbances between patients presenting with either sustained or nonsustained forms

Ventricular tachycardia (VT) is common among patients with Chagas' heart disease but the ultimate mechanisms responsible for its sustained and nonsustained forms are not understood. This study aimed at determining which factors differentiate between patients with sustained (S-VT) and nonsustained VT (NS-VT). Fifty-six consecutive chagasic patients with VT were prospectively selected: 28 patients with spontaneous S-VT and 28 patients with NS-VT. The patients underwent clinical, angiographic, electrophysiologic and myocardial perfusion examination. Syncope episodes (S-VT: 43% versus NS-VT: 11%, p = 0.007) and induction of S-VT by programmed ventricular stimulation (S-VT: 89% versus NS-VT: 7%, p = 0.001) were significantly more frequent in S-VT patients. Evidence of a scar-related reentry was observed in all 24 S-VT patients who underwent endocardial mapping for attempted radiofrequency ablation of 33 VTs. Overall, 29 VTs arose from the LV (88%) and 4 VTs arose from the RV (12%). Among these, 27 VTs (82%) were related to LV inferolateral scar, 2 VTs (6%) were related to LV apical scar, and 4 VTs (12%) were related to RV scars. A significantly higher prevalence of wall motion abnormalities (S-VT: 82% versus NS-VT: 46%, p = 0.005) and myocardial perfusion defects (basal segments, S-VT: 95.5% versus NS-VT: 44%, p = 0.001) was documented within the LV inferior and/or posterolateral regions in S-VT patients compared to NS-VT. In conclusion: (a) VT may arise from various regions in both ventricles, but LV inferolateral scar is the main source of S-VT reentrant circuits; (b) there is good topographic correlation between myocardial perfusion, wall motion abnormalities and areas that originate S-VT; (c) although to a lesser extent, wall motion and perfusion defects also occur in a relevant proportion of chagasics with NS-VT.