Radiofrequency Catheter Ablation of Idiopathic Left Ventricular Tachycardia:

Idiopathic Left Ventricular Tachycardia. Introduction: Idiopathic left ventricular tachycardia with a QRS pattern of right bundle branch block and left-axis deviation constitutes a rare but electrophysiologically distinct arrhythmia entity. The underlying mechanism of this tachycardia, however, is still a matter of controversy. This report describes findings in a 42-year-old man who underwent successful radiofrequency catheter ablation of idiopathic left ventricular tachycardia.
Methods and Results: On electrophysiologic study, the tachycardia was reproducibly induced and terminated with double ventricular extrastimuli. Intravenous verapamil terminated the tachycardia whereas adenosine did not. Detailed left ventricular catheter mapping during sinus rhythm revealed a fragmented delayed potential at the mid-apical region of the inferior site near the posterior fascicle of the left bundle branch. At the same site, continuous electrical activity throughout the entire cardiac cycle was recorded during ventricular tachycardia. Repeated spontaneous termination of this continuous electrical activity in late diastole was followed immediately by termination of the tachycardia. Single application of radiofrequency current for 20 seconds at this site completely abolished inducibility of the tachycardia. After catheter ablation, at the identical site of preablation recording of the fractionated potential during sinus rhythm, no fragmented delayed activity could be recorded. There was no complication from the ablation procedure.
Conclusion: The preablation recordings of fragmented delayed potentials during sinus rhythm and continuous diastolic electrical activity during tachycardia, together with ablation characteristics and previously reported electrophysiologic properties of this arrhythmia, may further support microreentry as the underlying mechanism in idiopathic left ventricular tachycardia.     

Radiofrequency Catheter Ablation of Left Ventricular Outflow Tract Tachycardia:

Left Ventricular Outflow Tract Tachycardia. Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. We report two patients whose QRS configuration during VT commonly showed an inferior axis and monophasic R waves in all the precordial leads. The mechanism of these VTs appeared to be triggered activity. From mapping and ablation, the origin of these VTs was determined to be in the most posterior LVOT, corresponding to the aortomitral continuity (left fibrous trigone).     

特发性室性心动过速的射频消融

目的:对经射频消融术证实的特发性室性心动过速的病例进行总结分析,探讨室性心动过速的发病状况、心电图特点、消融靶点的确定及消融结果。方法:对68 例特发性室性心动过速的起源部位和体表心电图进行分析,所有患者在诱发出室性心动过速后进行射频消融治疗,观察特发性室性心动过速的射频消融成功率和复发率以及它们和消融靶点的关系。结果:本组特发性室性心动过速患者中右室室性心动过速较左室室性心动过速多见。右室特发性室性心动过速心电图表现为左束支传导阻滞,左室特发性室性心动过速心电图则多表现为右束支传导阻滞。消融靶点的确定右室特发性室性心动过速主要采用起搏标测法,左室特发性室性心动过速主要采用激动顺序标测法。右室流出道室速组在起搏标测时起搏ECG和VT时ECG的12导联QRS波完全相同处消融成功率较高。结论:室性心动过速发作时的体表心电图可初步估计特发性室性心动过速的起源部位,射频消融术治疗特发性室性心动过速成功率高,并发症少。     

Radiofrequency Catheter Ablation of Sustained Monomorphic Ventricular Tachycardia in Hypertrophic Cardiomyopathy

Monomorphic VT in HCM. Introduction : Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm.
Methods and Results : The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal internals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds.
Conclusion : Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.     

Radiofrequency Catheter Ablation of Ventricular Tachycardia in Right Ventricular Cardiomyopathy:

RF Catheter Ablation of VT. Radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) in patients with a right ventricular (RV) cardiomyopathy has only rarely been successful. This report demonstrates reentrant VT in the setting of RV cardiomyopathy in which the tricuspid valve annulus acted as one of the harriers of an isthmus of slow conduction, identified by the presence of entrainment with concealed fusion. The RF pulse was further targeted by analysis of the relationship between the postpacing interval with the tachycardia cycle length, and of the local activation time with the stimulation time. Long-term clinical follow-up has documented no recurrent VT.     

Ablation of Ventricular Tachycardia with a Saline-Cooled Radiofrequency Catheter:

INTRODUCTION: In animal models, active cooling of the electrode during radiofrequency (RF) ablation allows creation of larger lesions, presumably by increasing the power that can be delivered without coagulum formation. These RF lesions have not been characterized in human myocardium in regions of infarction and scarring. METHODS AND RESULTS: Cooled-tip RF catheter ablation of ventricular tachycardias (VTs) was performed in two patients who had severe congestive heart failure and subsequently underwent cardiac transplantation. The first patient had four different monomorphic VTs. RF applications along the inferoseptal margin of a scarred region abolished all inducible VTs. The second patient had sarcoidosis involving the myocardium and four different inducible VTs. RF current applied at an inferobasal VT exit and at the right and left septa failed to abolish the VTs. The explanted hearts were examined at the time of cardiac transplantation 18 and 21 days later, respectively. Lesions extended to depths up to 7 mm, reaching clusters of myocardial cells deep to regions of fibrosis. Microscopically, the ablation sites contained coagulation necrosis with hemorrhage, surrounded by a rim of granulation tissue. CONCLUSION: Saline-irrigated RF catheter ablation produces relatively large lesions capable of penetrating deep into scarred myocardium.     

Radiofrequency Catheter Ablation of Left Ventricular Outflow Tract Tachycardia from the Coronary Cusp: A New Approach to the Tachycardia Focus

INTRODUCTION: Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during VT exhibited an atypical left bundle branch block and inferior axis. Pace mapping revealed that the origin of this VT was very close to the left sinus of Valsalva. Transcoronary cusp RF catheter ablation abolished the VT in this patient and is a new approach for the treatment of this kind of VT. The application of this approach to the other types of VT has yet to be determined.     

Catheter Ablation of Canine Ventricular Myocardium Utilizing Radiofrequency Current

To determine if catheter-delivered radiofrequency current (RFC) could safely destroy ventricular myocardium, 6P quadripolar catheters were inserted into the right ventricular and left ventricular endocardium of 11 heparinized, closed-chest dogs. RFC (continuous wave, 625 kHz) was delivered via a commercially available eiectrosurgical unit for 10–20 sec between the catheter tip and a surface electrode (unipolar configuration). Voltage delivered was 42 ± 8 volts with a current of 0.23 ± 0.07 amperes and an impedance of 182 ± 32 ohms. An average power of 9.8 ± 4.4 watts resulted in a delivered energy of 112 ± 60 joules. The catheters were repositioned in the right and left ventricular apices and RFC was delivered between the two tip electrodes for 10–20 sec (bipolar configuration). Voltage delivered was 44 ± 7 watts with a current of 0.20 ± 0.07 amperes and an impedance of 241 ± 49ohms. An averageof 8.5 ± 4.3 watts of power resulted on delivered energy of 106 ± 29 joules.
At necropsy, lesions were identified in 5/11 right and 9/11 left ventricular free-wall sites and 7/11 right and 11/11 left ventricular apical sites. Lesion size ranged from 4–8 mm in depth and 3–9 mm in diameter and the size did not correlate with energy delivered. The endocardial surface was grossly intact in all. No hemodynamic compromise, electrode pitting, or changes in postshock catheter resistance were noted. However, one dog had spontaneous ventricular fibrillation after a transseptal pulse. Although no large thrombi were noted, a thin layer of endocardial thrombus formation was usually present. We conclude that catheter-delivered RFC can selectively damage myocardial tissue with minimal complications.     

Tachycardia-Induced Cardiomyopathy Secondary to Right Ventricular Outflow Tract Ventricular Tachycardia: Improvement of Left Ventricular Systolic Function After Radiofrequency Catheter Ablation of the Arrhythmia

Cardiomyopathy Secondary to RVOT VT. Introduction : Several reports describe development of cardiomyopathics secondary to supraventricular tachycardia. Few reports have described cardiomyopathies secondary to ventricular tachycardia.
Methods and Results : We describe a patient who presented with dilated cardiomyopathy and repetitive nonsustained monomorphic ventricular tachycardia. Cardiac cathcterization showed hemodynamically insignificant coronary artery disease. Radiofrequency ablation of a right ventricular outflow tract ventricular tachycardia resulted in improvement of the left ventricular systolic function and resolution of heart failure symptoms.
Conclusions : This report suggests that right ventricular outflow tract ventricular tachycardia may cause reversible tachycardia-induced cardiomyopathy.     

射频消融治疗特发性室性心动过速103例

总结不同起源部位特发性室性心动过速(IVT)经导管射频消融(RFCA)治疗的成功经验。103例IVT行RFCA治疗,左室特发性VT(ILVT)起自间隔部者以最早的P电位处为靶点,右室特发性VT(IRVT)和其他部位的IVT均以起搏与VT发作时12导联心电图QRS波形态完全相同处或最早心室激动处为靶点。结果:RFCA治疗IVT的成功率为96.12%,ILVT为92.9%,IRVT为98.4%,复发率为2.9%。IVT起源部位分别位于左室后间隔部32例,左室游离壁1例,左室流出道9例,右室流出道60例、流入道1例。结论:IVTRFCA的关键是消融靶点的标测和确定,可根据VT发作时的心电图表现估计其起源位置。IVT的RFCA成功率高。     

Successful Radiofrequency Catheter Ablation of Sustained Ventricular Tachycardia Postmyocardial Infarction in Man Guided by a Multielectrode "Basket" Catheter

Multielectrode "Basket" Catheter. Currently, analysis of sustained ventricular tachycardia postmyocardial infarction in man is limited by the time required for single point activation mapping and the difficulty in obtaining information during hemodynamically unstable arrhythmias. To overcome these limitations, we developed a multielectrode "basket" catheter for endocardial recording and pacing. This report describes the first clinical use of such a catheter to guide successful radiofrequency ablation of incessant sustained ventricular tachycardia postmyocardial infarction. This system may significantly shorten the time required for VT analysis and improve the results of radiofrequency catheter ablation for VT postmyocardial infarction.     

Radiofrequency Catheter Ablation of Idiopathic Left Ventricular Tachycardia Originating in Both Left Posterior and Anterior Fascicles

A 45-year-old woman underwent radiofrequency ablation (RFA) for symptomatic idiopathic left ventricular tachycardia (ILVT). The clinical arrhythmias had two different patterns, a wide QRS tachycardia with right bundle branch block (RBBB) and left axis deviation (LAD) and another with RBBB and right axis deviation (RAD). The electrophysiology study localized the origin of tachycardias to the midinferior and superior ventricular septum, respectively. RFA terminated successfully ILVT with RBBB and LAD morphology, but another pattern could not be ablated. Noncontact mapping revealed the earliest site of activation at the superior septum. RFA at this site terminated successfully ILVT with RBBB and RAD.     

Tachycardia-Induced Right Ventricular Cardiomyopathy: Epicardial Radiofrequency Ablation of an Unusual and Unexpected Ventricular Tachycardia

A 38-year-old man without prior medical history was hospitalized for sustained monomorphic ventricular tachycardia (VT) left bundle branch block pattern with inferior QRS axis resistant to beta blockers. Right ventricular (RV) ejection fraction (EF) was 28%. Left ventricular EF was normal. Right and left endocardial ablation failed. Percutaneous epicardial radiofrequency application at the lateral mitral annulus was successful. The RVEF later normalized.
Some VTs originating from the left ventricular epicardium are potential mimickers of benign VTs originating from the ventricular outflow tract (right or left) or arrhythmogenic right ventricular cardiomyopathy VT and they may induce isolated RV dysfunction.     

Catheter Ablation of the Left Ventricular Outflow Tract Tachycardia from the Left Atrium

RF ablation of idiopathic left ventricular outflow tract ventricular tachycardia (LOT-VT) may imply in significant risk of damaging the proximal left main if RF pulses are being delivered from the left sinus of Valsalva or from inside an epicardial coronary vein. This report describes a new approach to control LOT-VT by means of RF catheter ablation.     

温度监测控制在室性心动过速射频消融中的应用

在７例左室特发性室性心动过速病人成功射频消融中，使用温度监测控制，发现消融时电极一组织界面温度迅速升高，经过一定时间达到两种稳定的温度状态。即４８℃左右（４８．７±２．０℃）和７０℃左右（６６．０±４．８℃）．其输出功率分别为４８Ｗ和２２±１０．３（１５～３５）Ｗ（Ｐ＜０．００１）。无论输出功率多少，用７Ｆｒ可控大头导管电极，在放电开始后约４ｓ，局部温度可达４８℃，而达设定温度（７０℃）需１０ｓ左右，通过温度监测控制提示：放电５～１０ｓ消融不成功，应重新进行标测。此结论与临床观察相吻合。     

环形标测电极指导下射频导管消融右心室流出道室性心动过速

探讨环形电极对右室流出道室性心动过速(RVOTVT)的标测指导作用及射频消融方法。6例特发性RVOTVT患者,男4例、女2例,年龄35.0±6.3(18～42)岁。行常规电生理检查,应用环形电极标测右室流出道,以最早激动点结合窦性心律下起搏标测确定靶点。结果:4例起源于右室流出道间隔前部,1例起源于间隔后部,1例起源于游离壁,6例均成功进行了射频消融,成功率100%。平均手术时间78±22min。结论:环形标测电极可以指导快速寻找室性心动过速起源点,缩短标测及消融时间。     

射频导管消融治疗室性早搏的研究进展

室性早搏的治疗,以往学者不主张对其进行药物处理,只是出现较明确的临床症状、患者精神上受较大的影响、且药物效果不好或不愿用药的情况,才推荐导管消融治疗。随着科技进步和人对高水平生活的追求,导管消融治疗室性早搏的适应证也相应调整了,现将在回顾文献的基础上,对经射频导管消融治疗室性早搏的现况作一概述。     

特发性室性心动过速的导管射频消融治疗

目的评价特发性室性心动过速(IVT)的导管射频消融(RFCA)治疗效果。方法20例IVT患者,男11例,女9例,年龄30.4±12.419～40岁。病史1～8年。心动过速频率146～240bpm。所有病例无器质性心脏病的证据。术前停用抗心律失常药物至少5个半衰期。常规心内电生理检查,采用起搏标测与激动标测相结合的方法进行标测,并行靶点消融。结果20例病人中,右室IVT9例,其中右室流出道VT8例,成功7例;希氏束下方VT1例,消融成功;左室IVT11例,其中间隔部VT10例,成功9例,左室游离壁VT1例,成功1例,总成功率90%(18/20)。18例术中成功诱发出VT,2例左室IVT患者术中未诱发出VT,采用起搏标测,记录到与自发VT心电图12导联完全一致的起搏心电图,消融3个月后,1例复发。结论RFCA治疗IVT疗效肯定,成功率高,复发率低。左室IVT应以激动标测为主,记录到最提前的浦肯野电位(PP)或异常电位(AP)提示为成功的靶点,且术中能否诱发出VT是手术成功的关键。右室IVT应以起搏标测为主。     

Anterior Q-Wave Infarction Complicating Attempted Catheter Electrode Ablation of Ventricular Tachycardia

This report describes an attempt to treat recurrent ventricular tachycardia by catheter electrode ablation. The procedure failed to control the arrhythmia and resulted in a Q-wave anteroseptal myocardial infarction. The potential complications of catheter electrode ablation in the normal ventricle are emphasized.     

Catheter Ablation of Repetitive Monomorphic Ventricular Tachycardia From Left Ventricular Outflow Tract Guided by Unipolar Mapping

Repetitive monomorphic ventricular tachycardia from the left ventricular outflow tract is an uncommon arrhythmia. Successful catheter ablation has been previously reported in a few cases, but a large number of applications were usually needed when an approach based on either activation mapping or pace mapping was used. In our patient, the selection of the target point for application was based exclusively on unipolar mapping criteria of the ectopic beats, resulting in a short procedure with successful outcome.