Therapy of "Idiopathic" Ventricular Tachycardia

"Idiopathic" Ventricular Tachycardia. Idiopathic ventricular tachycardias occur in "normal" hearts and are generally benign arrhythmias. They can arise from either the left or right ventricle, and the origin is usually predictable from the surface ECG. These arrhythmias are produced by diverse mechanisms. When treatment is indicated, empiric pharmacotherapy can he successful. However, if drugs are not tolerated or tail, radiofrequency (RF) ablation may he indicated. During electrophysiologic study, arrhythmia mechanism tan he determined, and pace and activation mapping can he used to localize the site of ventricular tachycardia origin to direct application of RF lesions. RF ablative therapy has been associated with high success rates.     

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.     

A Case with Occurrence of Antidromic Tachycardia After Ablation of Idiopathic Left Fascicular Tachycardia: Mechanism of Left Upper Septal Ventricular Tachycardia

A 36‐year‐old male presented with verapamil‐sensitive narrow QRS tachycardia. The patient underwent the catheter ablation of common idiopathic left fascicular ventricular tachycardia (ILVT) 2 years ago. During narrow QRS tachycardia, the diastolic and presystolic potentials (P1 and P2) were recorded at the left septum. Activation sequences of P1 and P2 were opposite from those in common ILVT. Entrainment of P1 at the upper septum exhibited concealed fusion and S‐QRS equal to P1‐QRS. Radiofrequency current to P1 suppressed VT. Idiopathic left upper septal VT might be the antidromic macroreentry of the common form of ILVT.     

Histologic Evolution of Radiofrequency Lesions in an Old Human Myocardial Infarct Causing Ventricular Tachycardia

Histology of RF Lesions. Introduction : Radiofrequency (RF) ablation of ventricular tachycardia (VT) late after myocardial infarction may be difficult due to characteristics of the infarct containing the reentry circuit. RF lesions in these infarcts in humans have not been characterized.
Methods and Results : Catheter mapping and ablation of VT originating from an anterior wall infarct was performed 8 days and again 12 hours prior to death. Pacing identified a region of abnormal conduction where RF ablation terminated VT. This region contained strips of myocytes sandwiched between endocardial fibrosis and dense scar. RF lesions ranged from 2 × 2 mm to 5 × 10 mm and were up to 3 mm in depth. Acute lesions showed superficial thrombus and early coagulation necrosis without inflammation. Older lesions showed coagulation necrosis, sparse neutrophil infiltrate, minimal granulation tissue, hemorrhage, and mixed inflammatory infiltrate along the lumen without re-endothelialization.
Conclusion : In this patient, RF lesions had sufficient depth but not width to interrupt the thin, but potentially broad, sheets of myocytes in the reentry circuit. In thinned areas, RF lesions can extend to the epicardium. Selecting sites with abnormal electrograms confines RF lesions to the infarct region. Inflammation and hemorrhage could conceivably cause delayed effects of RF.     

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。     

Entrance Site of the Slow Conduction Zone of Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia:

Entrance Site in ILVT. The entrance site of the slow conduction zone was identified by entrainment study in an 18 year-old woman with verapamil-sensitive idiopathic left ventricular tachycardia. Radiofrequency catheter ablation at this site eliminated the tachycardia. The entrance site was at a mid-septal location and was more than 2 cm away from the exit site. Electrophysiologic findings suggested macroreentry in the Purkinje system as the mechanism of idiopathic left ventricular tachycardia.     

Idiopathic Reentrant Right Ventricular Outflow Tract Tachycardia With Presystolic Potential of Central Pathway

Idiopathic Reentrant RVOT VT With Presystolic Potential . A 12‐year‐old girl with recurrent palpitation due to idiopathic ventricular tachycardia (VT) with a left bundle branch block configuration and inferior axis was referred to our hospital. During the VT, a spiky presystolic potential (SP) was recorded at the septum of right ventricular outflow tract (RVOT) just below pulmonary valve. The SP was entrained with a decremental property by pacing from right ventricular apex. Concealed entrainment was observed by pacing where the SP was recorded. Delivery of radiofrequency current targeting the SP abolished the VT. The SP with the decremental property could represent the central pathway of this idiopathic RVOT reentrant VT. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1174‐1177)     

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.     

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.     

射频消融特发性室性心动过速的标测方法初探（附五例分析）

５例特发性室性心动过速（ＶＴ）经射频电流导管消融（ＲＦＣＡ）而获治愈。本文从成功的ＲＦＣＡ结果着重探讨特发性ＶＴ兴奋灶的标测方法。心内膜激动时间标测，以局部电图较体表导联ＱＲＳ波时间提前≥１０ｍｓ处定为心室最早激动点（ＥＶＡ），５例平均心室最早激动至ＱＲＳ波起始时间为１８±１１．７ｍｓ，在ＥＶＡ处放电消融仅１例成功。采用起搏标测法定位以略低于自发ＶＴ的频率沿ＥＶＡ上下左右逐点标测，寻找起搏电图至少１１个导联的ＱＲＳ波形态、振幅、极性与自发ＶＴ相同的标测点放电消融，４例均获成功。消融成功的局部电图较ＱＲＳ波平均提前２６±１２．８ｍｓ。结果提示联合应用心内膜激动时间标测和起搏标测并侧重于后者，可能是提高ＲＦＣＡ特发性ＶＴ成功率的一种有效方法。     

Effect of Radiofrequency Catheter Ablation of Ventricular Tachycardia on Left Ventricular Function in Patients with Prior Myocardial Infarction

Introduction: Successful RF ablation of VT late after MI can involve multiple applications and long lines of RF lesions. The impact on left ventricular function is potentially important, but not well defined. Quantitative echocardiography was used to determine the effect of radiofrequency (RF) ablation on left ventricular function in patients with ventricular tachycardia (VT) after myocardial infarction (MI). Methods and Results: In 62 patients (55 men; age 67 ± 1.1 yr.) who underwent RF ablation for VT late after MI, left ventricular ejection fraction (LVEF) was quantified from digitized echocardiograms performed 1 week before and <72 hours after ablation. Patients received a mean of 25.6 ± 2.2 (range of 3–98) RF lesions. The LVEF pre- and post-ablation did not differ for the group (pre-LVEF 29.8 ± 11.9% vs. post-LVEF 29.5 ± 11.2%, p = 0.626), or for the 30 patients who received >25 RF lesions (Pre-LVEF 28.5 ± 11.1% vs. Post-LVEF 28.1 ± 10.8%, p = 0.74) or for the 7 patients who received >40 RF lesions (Pre-LVEF 29.9 ± 12.7% vs. Post-LVEF 29.2 ± 6.2%, p = 0.84). Although LVEF did not change for the group, LVEF increased >5% in 12/62 (19.4%) pts and decreased 5% in 14/62 (22.5%) pts. Patients with a decrease in EF did not differ from the remaining patients with respect to age, gender, number of RF lesions, or use of a cooled RF catheter, but did have a better initial EF (38.8 ± 12.2% versus 27.2 ± 10.6%, p = 0.001). Conclusion: Multiple RF ablation lesions confined to infarct regions do not measurably affect LV function, but a cautious approach, confining ablation lesions to areas of scar, as was attempted in this study, seems prudent.     

Analysis During Sinus Rhythm of Critical Sites in Reentry Circuits of Postinfarction Ventricular Tachycardia

Background: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites. Methods: In 33 patients (mean age 67 ± 11 yrs) with prior infarction, mapping and radiofrequency (RF) catheter ablation of 57 hemodynamically-tolerated VT's (cycle length 478 ± 96) were performed. The morphologies of electrograms (EGM) at sites of concealed entrainment (CE) were compared during SR and VT. RF energy was delivered at 94 sites (51 successful and 43 unsuccessful ablation sites). Results: During SR, isolated potentials (IP), but not late potentials (LP) recorded via the mapping catheter, were associated with successful ablation. At 29/39 sites with an IP during sinus rhythm, an isolated diastolic potential (IDP) also was present during VT, whereas at 4 sites IP's were present only during SR (p < 0.001). At 11/29 sites where isolated potentials were present during SR and VT, the morphology of the isolated potential during VT and SR was similar; and all but one of these sites were successful ablation sites (p = 0.01). The EGM amplitude during VT correlated with the amplitude during SR (R = 0.9, p < 0.001). An identical pacemap was present during SR at 33/94 sites; this was not associated with successful ablation. Conclusion: SR mapping may be helpful in identifying critical sites of reentry in postinfarction VT. At sites within the reentry circuit, characteristics of sinus rhythm EGM's that are associated with successful ablation include the presence of IP's, but not the presence of LP's.     

特发性室性心动过速射频消融中出现快速心室反应与消融成功关系探讨

探讨特发性室性心动过速 (IVT)射频消融中出现快速心室反应 (FVR)与成功消融的关系。观察IVT在射频消融中出现FVR的表现形式、发生率 ,成功消融与无效消融中FVR的特点。 2 8例IVT行射频消融 ,成功率 2 7/ 2 8(96 .4% ) ,均无并发症出现。FVR表现为 :①心动过速消融中出现加速室性心律后心动过速终止 ;②心动过速中间断出现窦性心律 ;③窦性心律中间断出现短阵室性心动过速 (VT)、双发或联律、室性早搏。统计结果表明 :有效消融时表现为心动过速在消融中 10余秒内终止 ,恢复窦律 ,窦律下进一步消融出现③或直接在窦律下消融出现③ ,FVR与VT形态相同 ,且随着消融过程进行 ,FVR室性QRS波个数由多至少直至消失。结论 :IVT射频消融中出现FVR很常见 ,其出现并不增加并发症的发生率 ;消融中FVR表现为室性QRS波形态与VT相同且个数由多至少直至消失为有效消融指标     

Idiopathic Right Ventricular Tract Outflow Tachycardia Induced by High‐Frequency Stimulation

Idiopathic Right Ventricular Tract Outflow Tachycardia Induced by High‐Frequency Stimulation. Ventricular tachycardia arising from the right ventricular outflow tract is one of the common forms of idiopathic ventricular tachycardia. One of the major challenges in mapping and ablation of idiopathic right ventricular outflow tract ventricular tachycardia is noninducibility. Direct stimulation of sympathetic nerves innervating the right ventricular outflow may provide an alternative approach to induce arrhythmia. We report a case of idiopathic right ventricular outflow tract tachycardia in whom tachycardia was noninducible by aggressive conventional stimulation protocols, which was induced by high‐frequency stimulation of proximal pulmonary artery and was successfully ablated. (J Cardiovasc Electrophysiol, Vol. 24, pp. 221‐223, February 2013)     

Late QRS Activity in Signal‐Averaged Magnetocardiography,Body Surface Potential Mapping,and Orthogonal ECG in Postinfarction Ventricular Tachycardia Patients

Background: Delayed electrical activity necessary for re‐entrant ventricular tachycardia (VT) is detectable noninvasively with high resolution techniques. We compared high resolution signalaveraged analysis of magnetocardiography (MCG), body surface potential mapping (BSPM), and orthogonal three‐lead ECG (SA‐ECG) in the identification of patients prone to VT after myocardial infarction (Ml). Methods: Patients with remote myocardial infarction and cardiac dysfunction were studied, 22 with (VT group) and 22 without VT (control group). MCG with seven channels and BSPM with 63 and SA‐ECG with three orthogonal leads were registered. After signal‐averaging and highpass filtering, three time domain analysis (TDA) parameters describing late electrical activity were computed: QRS duration (QRSd), root mean square amplitude (RMS) of the last 40 ms of QRS, and the duration of the low‐amplitude QRS end (LAS). Results: All parameters by each method were significantly different between the patients’groups. For example, LAS parameter in MCG was 59 (SD 22) ms in the VT group vs. 37 (SD 13) ms in controls (P < 0.001), 77 (SD 22) ms vs. 56 (SD 19) ms in BSPM (P = 0.002), and 60 (SD 24) ms vs. 39 (SD 22) ms in SA‐ECG (P = 0.005). The combination of LAS parameter in MCG and SA‐ECG resulted in improved performance in comparison to any single parameter with 95% sensitivity and 68% specificity. Conclusions: All three high resolution methods identified VT propensity among post‐Mi patients with cardiac dysfunction and between‐method differences were small. Information in MCG and SA‐ECG may be complementary and their combination could be of value in postinfarction arrhythmia risk assessment. A.N.E. 2002;7(4):389–398     

Ventricular Mapping During Atrial and Right Ventricular Pacing: Relation of Electrogram Parameters to Ventricular Tachycardia Reentry Circuits After Myocardial Infarction

INTRODUCTION: Ventricular tachycardia (VT) late after myocardial infarction is usually due to reentry in the border zone of the infarct area. Identification of critical parts of the VT reentry circuit by catheter mapping without needing to induce VT is a desirable goal for VT ablation. The aim of this study was to develop a model to predict reentry circuit locations based on characteristics of sinus or paced electrograms and pace mapping (PM) recorded from the infarct region. METHODS: Left ventricular electroanatomic mapping with the CARTO mapping system was performed in 16 male patients with recurrent VT late after myocardial infarction. A total of 1072 left ventricular sites were recorded during atrial pacing (AP) and right ventricular pacing (RVP), and the corresponding electrograms were analyzed for their local activation time (LAT), onset (ONS), end (END), duration (DUR), and amplitude (AMP) in each pacing sequence. At 1041 of these sites, PM was performed; the resulting stimulus to QRS intervals (S-QRS) was determined at 931 sites, the remaining 110 sites did not capture. All the obtained parameters were compared with the location of 18 ablation target areas with a radius of 2 cm defined by success of radiofrequency (RF) ablation or entrainment during VT, or both. RESULTS: Of 1072 sites, 227 (21%) were in the target and 845 (79%) were outside the target. All parameters were significantly different (p < 0.05) in AP and in RVP between inside and outside the target in a univariate analysis. In a multivariate analysis LAT, END, DUR, and AMP in AP, END and AMP in RVP, and S-QRS were independent predictors for the target (p < 0.05). A combination of selected parameters of these predictors (DUR in AP, AMP in RVP, and S-QRS) had a specificity of 64% with a sensitivity of 80% for the target. CONCLUSION: The observations suggest that ablation guided by a combination of abnormal electrograms in different rhythms can be useful to ablate VT and reduce the necessity of VT induction. Anatomically fixed regions of block may be important for reentry and be identifiable during sinus rhythm.     

射频消融术治疗特发性室性心动过速的临床分析

总结射频消融术治疗特发性室性心动过速（简称室速）２７例。左室特发性室速１７例均消融成功，其中１６例采用标测Ｖ波前最早Ｐ电位（浦肯野纤维电位）的方法；１例采用起搏标测的方法，成功靶点处均在左室间隔部。１例复发，再次消融成功。对１０例右室特发性室速采用起搏标测和激动标测的方法，其中８例消融成功，成功靶点７例在右室流出道、１例在流入道部位。成功８例中２例复发或再发，１例复发后电生理检查不能诱发室速，无法消融；１例再发左室室速，再次消融成功。２７例中１例出现静脉炎并发症。以上结果表明射频消融术是治疗特发性室速的安全有效方法。     

An Unusual Case Of Right Ventricular Outflow Tract Tachycardia

In this report, we describe an unusual case of right ventricular outflow tract (RVOT) tachycardia with episodes of repetitive monomorphic ventricular tachycardia (VT), paroxysmal sustained VT and incessant monomorphic VT of the same morphology. Diltiazem, adenosine, or metoprolol failed to interrupt these arrhythmias. However, administration of intravenous propafenone completely eliminated all ventricular ectopic activity. Electrophysiologic study performed off propafenone showed that the ventricular ectopic activity originated from a single locus at the anterior wall of the RVOT. Two radiofrequency applications at this site resulted in complete elimination of ventricular ectopic activity.     

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.