Mechanisms of Idiopathic Left Ventricular Tachycardia

Idiopathic Left Ventricular Tachycardia. Idiopathic left ventricular tachycardia (ILVT) differs from idiopathic right ventricular outflow tract (RVOT) tachycardia with respect to mechanism and pharmacologic sensitivity. ILVT can he categorized into three subgroups. The most prevalent form, verapamil-sensitive intrafascicular tachycardia, originates in the region of left posterior fascicle of the left bundle. This tachycardia is adenosine insensitive , demonstrates entrainment, and is thought to he due to reentry. The tachycardia is most often ablated in the region of the posteroinferior interventricular septum. A second type of ILVT is a form analogous to adenosine- sensitive RVOT tachycardia. This tachycardia appears to originate from deep within the interventricular septum and exits from the left side of the septum. This form of VT also responds to verapamil and is thought to he due to cAMP-mediated triggered activity. A third form of ILVT is propranolol sensitive. It is neither initiated or terminated by programmed stimulation, does not terminate with verapamil, and is transiently suppressed by adenosine, responses consistent with an automatic mechanism. Recognition of the heterogeneity of ILVT and its unique characteristics should facilitate appropriate diagnosis and therapy in this group of patients.     

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.     

Diagnosis and Ablation of Multiform Fascicular Tachycardia

Ablation Multiform Fascicular Tachycardia . Introduction: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies. Methods and Results : Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF. Conclusions : Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated. (J Cardiovasc Electrophysiol, Vol. 24, pp. 297‐304, March 2013)     

Comparison of Presystolic Purkinje and Late Diastolic Potentials for Selection of Ablation Site in Idiopathic Verapamil Sensitive Left Ventricular Tachycardia

BACKGROUND: Idiopathic verapamil-sensitive left ventricular tachycardia (ILVT) is the most common form of idiopathic left ventricular tachycardia (VT). Different methods have been proposed for ablation of ILVT. METHODS: Between June 2002 and February 2004, 15 patients (12 men; age 28 +/- 11 years, range 12 to 51) with ILVT underwent radiofrequency (RF) ablation at our center. We retrospectively assessed the significance of recording purkinje potential (PP) and late diastolic potential (DP) and its effect on selection of ablation target and number of RF application. RESULTS: Sixteen VTs were observed. The clinical VT had either RBBB and left axis morphology (14 cases) or RBBB and right axis morphology (2 cases). The QRS duration during tachycardia was 124 +/- 12 ms and the tachycardia cycle length was 356 +/- 53 ms. DP and PP were recorded at the targeted area for RF ablation in 11 and 9 patients respectively. The PP-Q interval, DP-Q interval and DP width were 18 +/- 4, 53 +/- 18 and 14 +/- 8 ms, respectively. The number of RF application was 7.2 +/- 4.3. Fewer applications were needed in whom RF ablation was initially targeted to PP (with or without DP) recording site (10 patients, 4.7 +/- 1.8) compared to those targeted to DP recording site (5 patients, 12.2 +/- 3.3) ( P < 0.05). CONCLUSION: Compared to DP alone, earliest PP (with or without concomitant DP) might be superior for selection of target site of RF ablation in patients with ILVT.     

左室特发性室性心动过速折返路径标测和消融点的选择

报道 1 0例 (男 8、女 2 )左室特发性室性心动过速 (简称室速 )折返路径标测结果和选择折返路径的不同部位为消融点的消融效果。电生理检查常规插入右室心尖与冠状静脉窦电极 ,并经左、右股动脉分别插入大头电极和2 8 2mm间距冠状静脉窦 1 0极标测电极至左室 ,后者贴靠在室间隔表面。窦性心律时各电极对可依次记录到His束电位 (HP)、左束支电位 (LBP)和左后分支的蒲氏纤维电位 (PP) ,室速时仍可同时记录到上述各电位 ,但顺序相反 ,PP领先 ,HP最后 ;而各部位的V波激动顺序在窦性心律和室速时是相同的 ,都是远端电极 (PP以远 )的V波最早 ,近端电极 (HP)的V波最晚。大头电极置于PP电极对附近。结果 :1 0例中 9例能记录到折返路径各电位心内电图 ,折返路径记录成功率为 90 % ( 9/1 0 )。第 1例大头电极位于PP电极对略上方处放电 ,消融成功 ,但导致完全性左束支阻滞。第 2 ,3例开始在PP电极对略下方处放电 ,但凡未记录到PP的点 ,虽然V波最早 ,都是放电无效点。最后消融成功的点 ,都记录到最领先的PP。第 4例以后 ,都必须记录到最领先的PP后才放电 ,除 1例 2次放电成功外 ,都是 1次放电成功。 1 0例随访至今 3～ 1 8个月 ,未服任何抗心律失常药均无室速发作。结论 :左室标测法不仅对研究左室特发性室速的折返     

射频消融治疗特发性室性心动过速疗效观察

目的 :评价射频消融术治疗特发性室性心动过速 (室速 )临床疗效。方法 :5 6例特发性室速患者中 ,34例左室特发性室速采用EPT小、中弯大头导管 (或Webstr小弯大头 ) ,在左室行激动顺序标测和消融 ,以P电位较QRS起点提前 2 0ms以上作为消融靶点。 2 2例右室流出道室速采用Webster加硬导管在右室流出道行起搏标测 ,以起搏时与心动过速时体表 12导联QRS形态完全相同或最接近处为消融靶点 ,成功标准为放电过程中心动过速终止且不能诱发。结果 :5 1例患者消融成功 ,成功率 91.1%。 34例左室特发性室速中 30例靶点位于左室间隔中下部 ,2例近左室心尖 ,1例左室流出道 ,1例位于间隔高位。 31例消融成功 ,1例失败 ,2例因导管到达间隔处机械刺激终止室速而不能再诱发 ,于终止室速处作为靶点射频消融 ,1例于术后第 2天、另 1例半年后室速复发。 2 2例右室流出道室速 ,16例位于流出道间隔侧 ,6例位于流出道游离侧壁。 19例起搏标测到与心动过速 12导联QRS形态完全相同靶点 ,1例形态接近 ,消融获成功。 2例未能诱发室速 ,射频消融 1个月心动过速重新出现 ,所有患者无并发症出现。结论 :射频消融术对特发性室速是一种安全有效的治疗方法 ,可作为首选治疗。电生理未诱发室速或机械刺激终止室速不宜尝试射频消融治疗。     

Retrograde Purkinje Potential Activation During Sinus Rhythm Following Catheter Ablation of Idiopathic Left Ventricular Tachycardia

Idiopathic Left VT and Purkinje Potentials . We describe two patients with idiopathic left ventricular tachycardia that were cured by radiofrequency catheter ablation. Tachycardia was inducible by ventricular stimulation and was verapamil sensitive. Two distinct presystolic potentials (PI and P2) were recorded during tachycardia in the mid-septal or inferoapical area, but only one potential (P2) was recorded during sinus rhythm. After catheter ablation at this site, the PI potential was noted after the QRS complex during sinus rhythm, while the P2 was still observed before the QRS complex. The P1 potential showed a decremental property during atrial or ventricular pacing. These data suggest that Purkinje tissue with decremental properties was responsible for the tachycardia mechanism, and that the reentry circuit involving this tissue is likely to be of considerable size.     

Radiofrequency catheter ablation of left ventricular tachycardia in the normal heart

Background: Radiofrequency (RF) catheter ablation is a safe and effective cure for many forms of supraventricular tachycardia. Its efficacy in the cure of right ventricular outflow tract tachycardia, and some forms of left ventricular tachycardia in patients with left ventricular dysfunction, has also been shown. In contrast limited data are available to assess the role of RF catheter ablation in treating idiopathic left ventricular tachycardia (ILVT), an unusual form of tachycardia occurring in patients without demonstrable heart disease.
Aim: To examine the efficacy and safety of RF catheter ablation in patients with ILVT.
Methods: Three patients without structural heart disease and with recurrent drug-refractory ILVT (right bundle branch block and left axis morphology) underwent electrophysiologic study (EPS) to initiate and localise the site of origin of their VT. RF catheter ablation of the VT focus was performed, with success being defined as failure to reinduce VT during incremental infusion of isoprenaline.
Results: In all three patients VT was inducible by rapid right atrial pacing and/or programmed ventricular stimulation, and could be terminated by intravenous verapamil. RF catheter ablation was successful in all patients. The site of successful ablation was common to each patient and was localised to the infero-apical aspect of the left ventricular septum. It was characterised by the recording of the earliest presystolic 'P' potential during both sinus rhythm and induced ILVT. No complications occurred during the procedure. During follow-up periods ranging from six to 12 months there were no symptomatic or documented episodes of recurrent ILVT.
Conclusions: We conclude that ILVT can be safely and effectively cured by RF catheter ablation.     

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.     

Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology

Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.     

Identification of the slow conduction zone in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia using electroanatomic mapping

Identification of the Slow Conduction Zone in a Macroreentry. Background: Although idiopathic left ventricular tachycardia (ILVT) has been shown to possess a slow conduction zone (SCZ), the details of the electrophysiological and anatomic aspects are still not well understood. Objective: We hypothesized that the SCZ can be identified using a 3‐dimensional electroanatomic (EA) mapping system. Methods : Ten patients with ILVT were mapped using a 3‐dimensional electroanatomic (EA) mapping system. After a 3‐dimensional endocardial geometry of the left ventricular was created, the conduction system with left Purkinje potential (PP) and the SCZ with diastolic potential (DP) in LV were mapped during sinus rhythm (SR) and ventricular tachycardia (VT) and were tagged as special landmarks in the geometry. The electrophysiological and anatomic aspects of it were investigated. Results: EA mapping during SR and VT was successfully performed in 7 patients, during VT in 3 patients. The SCZ with DPs located at the inferoposterior septum was found in 7 patients during SR and all patients during VT. The length of the SCZ was 25.2 ± 2.3 mm with conduction velocity 0.08 ± 0.01 m/s. No differences in these parameters were found between patients during SR and VT (P > 0.05). An area with PP was found within the posterior septum. A crossover junction area with DP and PP was found in 7 patients during SR and VT. This area with DP and PP during SR coincided or were in proximity to such area during VT and radiofrequency ablation targeting the site within the area abolished VT in all patients. Conclusion: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified and can be used to guide the ablation of ILVT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 840‐845, August 2012)     

特发性左室室性心动过速非接触球囊导管系统的标测与消融

介绍非接触球囊导管标测系统 (EnSite 30 0 0系统 )指导难治性特发性左室室性心动过速的标测与射频消融的初步经验。 5例男性病人 ,年龄 33± 17(17～ 6 2 )岁 ,常规方法标测和导管消融失败 2 .4± 1.1(1～ 4)次。常规放置高位右房和右室电生理导管 ,运用置入左室的 6 4极球囊导管和大头电极 ,系统重建三维心内膜几何模型和等电势 ,经右室导管诱发VT ,心动过速周期为 32 3.8± 48.1ms。EnSite 30 0 0系统标测到VT的最早激动点分别位于左后间隔中下部、左侧间隔后下部左束支下方、后下间隔近心尖部、左室后壁近基底部和左后间隔中部。在最早激动点和关键峡部分别行点状、环状和线性消融。 2例患者在心动过速时放电、3例患者在窦性心律时消融 ,均获成功。成功消融靶点处的单极电图均为QS型。X线曝光时间为 2 5± 12min。随访 7.8± 4.6 (1～ 11)个月所有患者均未发作心动过速。结果表明 ,与常规方法比较 ,EnSite 30 0 0系统所建立的心腔三维模拟等电势图可直观地显示心动过速的起源点、传导途径和关键峡部 ,系统模拟的单极腔内电图的形态也有助于判断病灶起源部位及提高消融成功率 ,尤其适用于常规方法消融失败的室性心律失常的标测 ,其独特的导航系统可引导消融导管到达靶点部位指导射频消融 ,并可减少X?     

左室特发性室性心动过速常规方法消融困难的线性消融

目的:探讨在常规方法消融困难的左室特发性室性心动过速（ILVT）患者中室间隔左室面线性消融的有效性。方法: 18例术中不能诱发持续性心动过速或发作时不能耐受患者,进行室间隔左室面心尖到心底部连线的前1/3～1/2区域,在窦性心律下首先标到蒲肯野氏纤维电位（PP）,向下至室间隔与左室下壁交界、向上至前后间隔中线进行线性消融,术后门诊或电话随访。结果: 所有患者术后即刻均未能诱发出ILVT。随访3~35（23±13）个月,3例/18例（17%）复发,远期成功率达83%,无1例发生永久性的并发症。结论: 对于术中不能诱发持续性心动过速或发作时不能耐受的ILVT患者,室间隔左室面线性消融安全有效,可以作为补救性消融措施。     

Idiopathic verapamil-sensitive sustained left ventricular tachycardia

Idiopathic verapamil-sensitive left ventricular tachycardia (VT) has characteristic QRS configurations during VT: right bundle-branch block with either left axis or right axis (less common) deviation. QRS duration is relatively narrow (0.13-0.16s) and frequently endocardial activation prior to QRS is recorded during VT, which is the basis of its being called fascicular tachycardia. The mechanism is probably reentry, but the nature of the slow conduction necessary for the occurrence of reentry is quite different from that of other sustained monomorphic VT associated with structural heart disease. Chronic oral verapamil therapy is the drug of choice for alleviation of symptoms. Long-term prognosis is good.     

Bundle Branch Reentry Ventricular Tachycardia with Two Distinct Left Bundle Branch Block Morphologies

Bundle Branch Reentry VT with Two Morphologies. Introduction: Bundle branch reentry ventricular tachycardia (VT) is usually amenable to treatment with radiofrequency ablation. Different QRS morphologies during VT are possible when anterograde ventricular activation is over the left bundle branch. Manifestations of tbis reentrant tachycardia with more than one QRS morphology with anterograde activation via the right bundle have not been reported and would be unusual due to the more discrete anatomy of the right bundle branch. Methods and Results: An electropbysiologic study was conducted in a patient with dilated ventricle and diminished ventricular function with VT, Typical characteristics of bundle branch reentry were noted when VT was induced. The study was notable for the presence of a right bundle recording only during macroreentrant beats or VT and the distal location of the recording. Radiofrequency ablation was performed. Postablation stimulation again induced VT, proven to be of the same bundle branch reentry mechanism but of a different QRS morphology. A second ablation was required for complete ablation of this patient's bundle branch reentry VT. Conclusion: In bundle branch reentry utilizing the left bundle as the retrograde limb and the right bundle branch as the anterograde limb of the circuit, VT of more than one distinct morphology can be seen. Careful evaluation to assess for the persistence of VT of the same mechanism is necessary to ensure complete ablation of the reentrant circuit. Preexisting right bundle disease and a dilated heart with more dispersed distal right bundle branches may predispose to such a phenomenon.     

Epicardial Macro-Reentrant Ventricular Tachycardia Exhibiting an Endocardial Centrifugal Activation Pattern in a Case with Arrhythmogenic Right Ventricular Cardiomyopathy

A 55-year-old man with arrhythmogenic right ventricular cardiomyopathy underwent catheter ablation of ventricular tachycardia (VT) with left bundle branch block and left superior axis QRS morphology with an early precordial transition. Endocardial mapping during the VT revealed a focal activation pattern from a small region of low voltage in the left ventricular (LV) septum. Despite earliest endocardial activation in the LV septum, epicardial mapping demonstrated a macro-reentrant circuit with successful catheter ablation at an inferior peritricuspid annular site. Activation from the reentrant circuit propagated through the scar area in the epicardial right ventricle to the remote endocardial LV breakout site.     

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).     

Radiofrequency Ablation of Idiopathic Left Anterior Fascicular Tachycardia

Left Anterior Fascicular Tachycardia. Introduction: A 45-year-old man with idiopathic ventricular tachycardia (VT) having a right bundle branch block configuration with right-axis deviation underwent au electrophysiologic test.
Methods and Results: Mapping demonstrated a site on the auterobasal wall of the left ventricle where there was an excellent pace map and an endocardial activation time of -20 msec, hut radiofrequency catheter ablation at this site was unsuccessful. At a nearby site, a presumed Purkinje potential preceded the QRS complex by 30 msec during VT and sinus rhythm, and catheter ablation was effective despite a poor pace map and an endocardial ventricular activation time of zero.
Conclusion: Idiopathic VT with a right bundle branch configuration and right-axis deviation may originate in the area of the left anterior fascicle. A potential presumed to represent a Purkinje potential may he more helpful than endocardial ventricular activation mapping or pace mapping in guiding ablation of this type of VT.     

Long‐Term Outcome After Catheter Ablation for Left Posterior Fascicular Ventricular Tachycardia Without Development of Left Posterior Fascicular Block

Long‐Term Outcome After Substrate‐Based Ablation of LPF VT During SR . Background: Catheter ablation of left posterior fascicular (LPF) ventricular tachycardia (VT) is commonly performed during tachycardia. This study reports on the long‐term outcome of patients undergoing ablation of LPF VT targeting the earliest retrograde activation within the posterior Purkinje fiber network during sinus rhythm (SR). Methods: This study retrospectively analyzed 24 consecutive patients (8 female; mean age 26 ± 11 years) referred for catheter ablation of electrocardiographically documented LPF VT. Programmed stimulation was performed to induce tachycardia, while mapping and ablation was aided by use of a 3D electroanatomical mapping system. Catheter ablation targeted the earliest potential suggestive of retrograde activation within the posterior Purkinje fiber network (retro‐PP) recorded along the posterior mid‐septal left ventricle during SR if LPF VT was noninducible. Results: Overall, 21/24 (87.5%) patients underwent successful catheter ablation in SR targeting the earliest retro‐PP, while 3/24 (12.5%) patients were successfully ablated during tachycardia. In none of the patients, ablation resulted in LPF block. No procedure‐related complications occurred. After a median follow‐up period of 8.9 (4.8–10.9) years, 22/24 (92%) patients were free from recurrent VT. Conclusion: In patients presenting with LPF VT, ablation of the earliest retro‐PP along the posterior mid‐septal LV during SR results in excellent long‐term outcome during a median follow‐up period of almost 9 years. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1179–1184, November 2012)     

Verapamil-Sensitive Left Anterior Fascicular Ventricular Tachycardia: Results of Radiofrequency Ablation in Six Patients

Verapamil-Sensitive Left Anterior Fascicular VT. Introduction: Verapamil-sensitive left ventricular tachycardia (VT) with a right bundle branch block (RBBB) configuration and left-axis deviation bas been demonstrated to arise from the left posterior fascicle, and can be cured by catheter ablation guided by Purkinje potentials. Verapamil-sensitive VT with an RBBB configuration and right-axis deviation is rare, and may originate in the left anterior fascicle. Methods and Results: Six patients (five men and one woman, mean age 54 ± 15 years) with a history of sustained VT with an RBBB configuration and right-axis deviation underwent electrophysiologic study and radiofrequency (RF) ablation. VT was slowed and terminated by intravenous administration of verapamil in all six patients. Left ventricular endocardial mapping during VT identified the earliest ventricular activation in the anterolateral wall of the left ventricle in all patients. RF current delivered to this site suppressed the VT in three patients (ablation at the VT exit). The fused Purkinje potential was recorded at that site, and preceded the QRS complex by 35, 30, and 20 msec, with pace mapping showing an optimal match between the paced rhythm and the clinical VT. In the remaining three patients, RF catheter ablation at the site of the earliest ventricular activation was unsuccessful. In these three patients, Purkinje potential was recorded in the diastolic phase during VT at the mid-anterior left ventricular septum. The Purkinje potential preceded the QRS during VT by 66, 56, and 63 msec, and catheter ablation at these sites was successful (ablation at the zone of slow conduction). During 19 to 46 months of follow-up (mean 32 ± 9 months), one patient in the group of ablation at the VT exit bad sustained VT with a left bundle branch block configuration and an inferior axis, and one patient in the group of ablation at the zone of slow conduction experienced typical idiopathic VT with an RBBB configuration and left-axis deviation. Conclusion: Verapamil-sensitive VT with an RBBB configuration and right-axis deviation originates close to the anterior fascicle. RF catheter ablation can be performed successfully from the VT exit site or the zone of slow conduction where the Purkinje potential was recorded in the diastolic phase.