Substrate Characterization and Catheter Ablation for Monomorphic Ventricular Tachycardia in Patients With Apical Hypertrophic Cardiomyopathy

VT Ablation in Apical Hypertrophic Cardiomyopathy . Introduction: Monomorphic ventricular tachycardia (VT) is uncommon in apical hypertrophic cardiomyopathy (HCM). The purpose of this study was to define the substrate and role of catheter ablation for VT in apical HCM. Methods: Four patients with apical HCM and frequent, drug refractory VT (mean age of 46 ± 10 years, left ventricular [LV] ejection fraction; 54 ± 14%) underwent catheter ablation with the use of electroanatomic mapping. Endocardial mapping was performed in 4 patients and 3 patients underwent epicardial mapping. Results: In 3 patients, VT was related to areas of scar in the apical LV where maximal apical wall thickness ranged from 14.5 to 17.8 mm, and 2 patients had apical aneurysms. Endocardial and epicardial substrate mapping revealed low voltage (<1.5 mV) scar in both endocardial and epicardial LV in 2 and only in the epicardium in 1 patient. Inducible VT was abolished with a combination of endocardial and epicardial ablation in 2 patients, but was ineffective in the third patient who had intramural reentry that required transcoronary ethanol ablation of an obtuse marginal vessel for abolition. The fourth patient had focal nonsustained repetitive VT from right ventricular outflow tract (RVOT), consistent with idiopathic RVOT‐VT, that was successfully ablated. During follow‐ups of 3‐9 months, all patients remained free from VT. Conclusion: Monomorphic VT in apical HCM can be due to endocardial, epicardial or intramural reentry in areas of apical scar. Epicardial ablation or transcoronary alcohol ablation is required in some cases. (J Cardiovasc Electrophysiol, Vol. 22, pp. 41‐48, January 2011)     

Successful Catheter Ablation of Hemodynamically Unstable Monomorphic Ventricular Tachycardia in a Patient with Hypertrophic Cardiomyopathy and Apical Aneurysm

Patients with hypertrophic cardiomyopathy (HCM) and left ventricular (LV) apical aneurysm represent a previously under-recognized but important subgroup within this heterogeneous disease spectrum. Apical aneurysms and the contiguous areas of myocardial fibrosis have been associated with monomorphic ventricular tachycardia (VT) and increased risk for adverse clinical events including sudden cardiac death, prioritizing the application of primary prevention implantable defibrillators. However, VT may be repetitive, thereby raising considerations for additional treatment strategies such as radiofrequency ablation. In this report, we describe such a patient with HCM and apical aneurysm in whom the mapping and ablation procedure was effective in identifying and abolishing the VT focus.     

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.     

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.     

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 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.     

Electrophysiological Mapping and Radiofrequency Catheter Ablation for Ventricular Tachycardia in a Patient with Peripartum Cardiomyopathy

A 38‐year‐old female with prior failed endocardial ablation for ventricular tachycardia (VT) was referred for further treatment. She had been diagnosed with peripartum cardiomyopathy 7 years before and had persistent left ventricular dysfunction with an ejection fraction of 20%. Epicardial voltage mapping showed extensive epicardial scar despite absence of endocardial scar. Five distinct VT morphologies were induced. Ablation was aided by electrogram characteristics, pace mapping, entrainment mapping, and establishing electrical inexcitability along areas of epicardial scar. After epicardial ablation no sustained VT was induced. She had been doing well without VT occurrence but died 1 year later unexpectedly at home.     

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.     

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).     

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.     

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.     

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。     

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.     

Mid‐ventricular Hypertrophic Obstructive Cardiomyopathy with Apical Aneurysm Complicated with Syncope by Sustained Monomorphic Ventricular Tachycardia

Mid‐ventricular hypertrophic obstructive cardiomyopathy with secondary formation of apical aneurysm is a rare variant of hypertrophic cardiomyopathy. They have a unique behavior because unlike other variants it causes sustained monomorphic ventricular tachycardia, which makes it particularly severe.     

Radiofrequency Catheter Ablation of Multiple Morphologies of Ventricular Tachycardia by Targeting a Single Region of the Left Ventricle

Radiofrequency Ablation of Multiple VTs. Introduction : As treatment options for ventricular tachycardia (VT) continue to evolve, the use of radiofrequency catheter ablation is rapidly expanding. However, in the presence of multiple morphologies of VT, achieving successful results may seem less likely. We report two patients with multiple morphologies of VT who underwent successful radiofrequency ablation by application of adiofrequency energy to a single region in the left ventricle.
Methods and Results : Two patients, each without any apparent cardiac dysfunction and a history of documented VT, were referred to our institution for further management. They underwent an electrophysiologic study and were found to have easily inducible VT, of three morphologies in one patient and two in the other. Using a transaortic approach, left ventricular mapping was performed for detecting a site with presystolic potentials, earliest ventricular activation, or both. Application of radiofrequency energy to a single area in the left ventricle resulted in the elimination of all previously inducible VT in each patient.
Conclusion : VTs with distinctly different morphologies can occur in patients with no detectable structural heart disease. These VT circuits may share a common pathway and, therefore, may readily be amenable to therapy with radiofrequency catheter ablation.     

Electroanatomical Mapping‐Guided Endocardial and Epicardial Ablation of Sustained Ventricular Tachycardia Originating From Alcohol Septal Ablation‐Induced Scar in a Patient With Hypertrophic Obstructive Cardiomyopathy

Ventricular Tachycardia After Alcohol Septal Ablation. A 76‐year‐old female developed 2 different ventricular tachycardias (VTs) 5 years after alcohol septal ablation (ASA) for symptomatic hypertrophic obstructive cardiomyopathy. VT#1 was a small macroreentry at the anterior border of the low‐voltage zone, suggesting the ASA‐scar and eliminated by endocardial ablation at a site recording fractionated potentials covering the mid‐diastolic and presystolic periods. VT#2 was a focal VT and eliminated by epicardial cryoablation at the basal posterior left ventricle, suggesting the posterior border of the ASA‐scar. Using the electroanatomical mapping, we demonstrated that the mechanism of the VTs was reentry at the edge of the ASA‐scar. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1296‐1299, November 2010)     

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。     

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.