Prevalence and characteristics of idiopathic outflow tract tachycardia with QRS alteration following catheter ablation requiring additional radiofrequency ablation at a different point in the outflow tract

Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.     

右心室流出道室性心动过速的射频消融治疗

目的 评价射频消融治疗右心室流出道室性心动过速(室速)的有效性和安全性.方法 对37例右心室流出道室速患者进行射频消融治疗,观察其疗效及安奎性,并随访观察复发的情况.结果 37例右心室流出道室速经射频消融治疗成功33例,成功率为89.2%,复发2例,无严重的并发症.结论 射频消融治疗右心室流出道室速是一种安全有效的治疗手段.     

左室流出道室性心律失常的射频消融治疗

目的 探讨起源于左室流出道少见部位的室性心动过速和/或频发室性早搏的心电图特点和射频消融治疗.方法 3例左室流出道室速和/或室早患者,术中进行激动和起搏标测,同时结合冠状动脉造影或三维电解剖标测系统(CARTO)定位.结果 3例患者中2例体表心电图特点类似右室流出道间隔部室速及室早,经腔内电生理证实起源于主动脉根部右冠窦内.1例起源于主动脉瓣-二尖瓣连接区(AMC),该部位室速及室早特有的典型心电图表现为II、III、aVF及所有胸前导联QRS波均呈R形.3例患者消融后观察2~24个月,均无复发.结论 右冠窦和AMC是左室流出道室速和/或室早的少见特殊起源部位,根据体表心电图形态,结合多种腔内标测技术及冠脉造影,能进行准确定位及成功消融.     

Pleomorphic ventricular tachycardia: an uncommon presentation in idiopathic left ventricular tachycardia

Idiopathic left ventricular tachycardia (ILVT) is a distinct entity that arises in the left ventricle, may have reentrant mechanism and is verapamil-sensitive. Pleomorphism as defined by multiple ventricular tachycardia morphologies is usually associated with either coronary artery disease or cardiomyopathy but very rare in cases of ILVT. In this case report, we describe an unusual case of ILVT with two ECG morphologies of the opposite axis that were successfully eliminated with radiofrequency ablation. The successful ablation sites were closely located to each other in the left lower ventricular septum.     

Unusual features of an idiopathic ventricular tachycardia arising from the left ventricular outflow tract

We encountered a 40-year-old man with recurrent symptomatic palpitations manifested as monomorphic ventricular tachycardia (VT) of a right bundle branch block (RBBB) pattern with an inferior frontal axis. Physical examination, chest roentgenogram, and echocardiogram were unremarkable. The VT could be provoked by treadmill exercise testing. Electrophysiologic study revealed that the VT could be reproducibly initiated with either atrial or ventricular pacing at cycle lengths between 500 and 400 ms. With overdrive ventricular pacing, the VT could be terminated. Of note was the observation that intravenous adenosine was not effective, but intravenous verapamil could interrupt the VT. The VT was pace mapped to be arising from a site at the left ventricular outlet tract (LVOT). Notably, during pace mapping, the pacing spike was immediately followed by the beginning of the paced QRS complex, and during VT, there was no time delay between the earliest local activation and the onset of QRS complex. Furthermore, there was no mid-diastolic activity or Purkinje potential that could be recorded during sinus rhythm and VT. Subsequently, the VT was successfully ablated with radiofrequency energy as guided by pace mapping. In summary, an idiopathic VT arising from the LVOT was found to be cycle lengths- and catecholamine-dependent, adenosine-insensitive but verapamil responsive. These unusual features suggest that either microreentry or triggered activity could be the underlying mechanism.     

New simplified technique for 3D mapping and ablation of right ventricular outflow tract tachycardia

OBJECTIVE: To evaluate the safety and efficacy of using a circular multielectrode catheter for mapping and ablation of ventricular tachycardia (VT) or premature ventricular complexes (PVCs) from the right ventricular outflow tract (RVOT). BACKGROUND: Three-dimensional (3D) mapping systems are commonly used for mapping and ablation of RVOT VT and PVCs. Newer catheters that are circular with multiple electrodes, such as the Lasso catheter, are capable of simultaneously recording from multiple points within a circumferential plane. Given the tubular structure of the RVOT, these catheters could be used for mapping tachycardias from the RVOT. METHODS: A retrospective cohort study of patients undergoing radiofrequency (RF) ablation of RVOT VT or PVCs was performed. In group 1 (n = 7), mapping was performed with a single ablation catheter and fluoroscopy. In group 2 (n = 10), 3D mapping using ESI (n = 9) or CARTO (n = 1) was performed. In group 3 (n = 12), mapping was performed with a circular multielectrode catheter (n = 12). All ablations were performed with 4-mm tip catheters using RF energy. RESULTS: Catheter ablation for RVOT VT (n = 15) or PVCs (n = 14) was performed on 29 cases in 26 patients, 9 males. Mean age was 35.9 years. In groups 1, 2, and 3, the mean number of lesions was 17.7 +/- 7.7, 13.6 +/- 7.7, and 18.2 +/- 22.7 and the median number of lesions was 20, 13, and 5, respectively. There were no significant differences in the number of lesions, RF time, fluoroscopy time, procedure time, and acute success rate among the three techniques. There were three complications in group 2 and one in group 3. CONCLUSION: The use of a circular multielectrode catheter is as effective as the other standard available 3D mapping techniques, both in terms of procedural success and procedural characteristics. Additionally, because of the lower cost associated with using the circular multielectrode catheter approach, further evaluation should be performed to determine whether this is the most cost-effective approach to 3D mapping and ablation of RVOT tachycardias.     

The surface electrocardiographic changes after radiofrequency catheter ablation in patients with idiopathic left ventricular tachycardia

Surface electrocardiographic changes after radiofrequency (RF) catheter ablation (RFCA) were observed in patients with idiopathic left ventricular tachycardia (ILVT), and the possible mechanisms were analysed. In 41 cases with ILVT who underwent the RFCA, the surface electrocardiograms (ECGs) before and after RFCA were recorded and the serum cardiac troponin I (cTnI) were measured before, immediately after, 4 h after and 24 h after RFCA. Seven patients developed different models and degrees of fascicular block after successful RFCA. The configurations of fascicular block had no dynamic alteration during the follow-up periods. No significant difference in the duration of the RF energy delivered, the numbers of RF lesion and the serum levels of cTnI between the patients with or without the electrocardiographic alteration was observed. Thus, the RFCA can cause the fascicular block in some of the patients with ILVT. The different distribution models of the left bundle branch, but not the damage degree to the endocardium induced by RF current, is the primary factor to the changes of ECG.     

Repetitive monomorphic ventricular tachycardia of left coronary cusp origin

Repetitive monomorphic ventricular tachycardia with a morphology of inferior axis and left bundle branch block pattern in patients without structural heart disease commonly originates from the right ventricular outflow tract. We report the case of a 22-year-old man with an incessant, monomorphic ventricular tachycardia with a similar morphology originating from the left coronary cusp, which was confirmed by perfect pace mapping, local ventricular activation preceding the onset of QRS by 25 mse, and eliminated by a single delivery of low-energy (11 W) radiofrequency currents.     

频发右心室流出道室性期前收缩对右心室流出道结构影响的研究

目的 探讨右心室流出道(RVOT)起源频发室性期前收缩对RVOT结构的影响.方法 选取2009～2011年行射频消融治疗的频发RVOT起源室性期前收缩患者30例,分析其心电图特征、动态心电图、心脏彩色超声结果及术中精确定位,分析室性期前收缩对RVOT结构的影响.结果 射频消融术前RVOT直径为(31.76±3.33)mm,术后6个月为(30.93±2.68)mm(P＜0.01);相关性分析显示:RVOT直径与室性期前收缩负荷呈正相关(r=0.484,P＜0.05).RVOT间隔部来源室性期前收缩QRS时限为(157.69±18.33) ms,游离壁来源室性期前收缩QRS时限为(179.23±16.05)ms(P＜0.01),QRS时限与来源部位相关(r=0.566,P＜0.01).室性期前收缩QRS时限与RVOT直径无相关性(r=0.097,P＞0.05).结论 RVOT来源室性期前收缩经射频消融治疗后,RVOT直径有减小的趋势,其与室性期前收缩负荷呈正相关,与室性期前收缩形态无相关性.     

Evaluation of left ventricular false tendons in children with idiopathic left ventricular tachycardia

Background

Left ventricular false tendons (FT) traverse the ventricular cavity and are thought to have some association with idiopathic left ventricular tachycardia (ILVT). However, reported prevalence of FT varies widely, making correlation difficult. Superior echocardiographic windows of pediatric patients may permit better analysis of FT in ILVT. Our study describes the relationship between FT and ILVT in young patients.

Methods

Retrospective case‐control study of 30 ILVT patients with 98 controls compared for FT. Diagnosis of ILVT was made by electrocardiogram and clinical history, and for 25 patients was further confirmed by electrophysiology study (EPS). Presence of FT was identified by one blinded observer and verified by a second blinded observer. Presence of FT was then compared between ILVT patients and controls using Fisher's exact test.

Results

Presence of FT did not differ significantly between patients and controls (53% vs 43%, P  =  0.40). Twelve FT patients (19%) had multiple FTs detected, though the incidence of ILVT was no higher in the setting of multiple FTs. A total of 25 patients with ILVT underwent EPS for intended ablation therapy, with ultimate success in 22/25 (88%) after one or more ablation sessions. Of the 25 EPS patients, FTs were present in 11, but precise correlation between successful ablation location and FT location was not possible since intraprocedural echocardiography was not performed in this patient group.

Conclusions

Presence of FTs did not differ between ILVT patients and controls. While FTs are not absolutely required for ILVT, they may still play a role in some cases.

     

Primary radiofrequency ablation for incessant idiopathic ventricular tachycardia

Fascicular VT and RVOT tachycardia are sometimes difficult to induce by programmed electrical stimulation (PES), despite pharmacologic provocation. In such instances, catheter mapping is hampered and efficacy of catheter ablation is difficult to judge. The study included nine patients who presented with incessant idiopathic VT and were directly taken to the electrophysiological laboratory for RF ablation. During the same period, elective ablation was performed on 108 patients with idiopathic VT. The success rate, procedural and fluoroscopy times number of energies, and the peak temperature were evaluated and compared. Of the nine patients, seven had incessant fascicular VT and two had RVOT tachycardia. The mean VT cycle length was 356 +/- 32 ms and the earliest endocardial activation time during VT was 23.6 +/- 6 ms relative to surface QRS complexes. A fascicular potential was not seen in three of the seven patients with fascicular VT. The mean procedural time was 71 +/- 32 minutes and 144 +/- 40 minutes (P = 0.023) while the fluoroscopy time was 14.6 +/- 4.6 minutes and 30 +/- 16 minutes (P < 0.001), respectively, in the primary ablation and elective groups. The total number of RF energies delivered was 2.0 +/- 1.3 versus 7.4 +/- 5.6 (P = 0.07), respectively. The significantly increased procedural time during elective ablation was largely due to time spent in fascicular VT induction. All patients in the primary ablation group were successfully ablated and none had a recurrence. Primary ablation is a safe and effective option in patients with incessant idiopathic VT. Moreover, in fascicular VT, it is superior to elective ablation in terms of success, fluoroscopy and procedural times.     

射频消融治疗特发性室性心动过速的临床观察

目的观察射频消融(RFCA)治疗9例特发性室性心动过速(IVT)方法和结果。方法分别行激动顺序标测法和起搏标测法,对左室特发性室速(ILVT)7例,右室特发性室速2例,行射频消融治疗。结果6例ILVT射频消融治疗成功,均起源于左室间隔面,有效消融靶点处P电位较体表心电图QRS起始点提前(34.6±8.9)m s(25~58 m s),2例IRVT射频消融成功,有效消融靶点处与心动过速时的12导联心电图QRS波形完全相同。无一例出现并发症。结论射频消融是治疗特发性室性心动过速的有效方法。     

左心室特发性室性心动过速射频消融成功判断标准的可靠性研究

目的根据经射频消融治疗的左室特发性室性心动过速患者,术中诱发室性心动过速程序的变化以及随访结果,评价室性心动过速消融成功标准的客观性,寻找更可靠的判断标准。方法1994-2008年消融成功并得到随访的146例特发性室性心动过速患者的临床发病情况;第1组68例,常规方法;第2组51例,常规方法结合靶点刺激;第3组27例,导管消融使其体表心电图成为左后分支阻滞图形,在此基础上重复第2组方法。观察3种方法对复发率的影响。结果①38.7％的患者在术中诱发窗口不稳定,存在着随手术时间延长室性心动过速不易诱发的特点。②第1组68例患者复发率为8.8％,第2组51例复发率为3.9％,第3组27例复发率为0％,第3组复发率明显低于第1组。结论形成左后分支阻滞的消融策略结合靶点刺激,有助于提高效果判断的可靠性。     

导管射频消融治疗右室流出道室性早搏的护理

目的探讨导管射频消融治疗右室流出道室性早搏的护理方法。方法对52例右室流出道室性早搏患者,采用射频消融治疗,并给予心理护理和基础护理。结果52例均完成了射频消融治疗。随访2~60个月,根治率92.3%(48/52),有效率98.1%(51/52)。结论合理、细致的护理可消除患者的恐惧心理,提高手术耐受性,且能及早发现和防治并发症,增加手术的安全性。     

经导管射频消融治疗右室流出道室性期前收缩

目的　评价经导管射频消融治疗单形性右室流出道室性期前收缩的有效性和安全性。方法　采用射频导管消融术对 4 2例症状严重的正常心脏单形性右室流出道室性期前收缩进行治疗 ,男 2 8例 ,女 14例 ,年龄 (42 .2±7.8)岁。将消融电极送至右室流出道区域 ,采用起搏标测和激动顺序标测 ,前者以起搏时与室性期前收缩QRS波形态完全相同为消融靶点 ,后者以室性期前收缩时最早心室激动点为消融靶点。 4 2例室性期前收缩全部起源于右室流出道 ,呈左束支阻滞图形 ,其中 36例起源于右室流出道间隔部 ,6例起源于右室流出道游离壁。以室性期前收缩在放电后 10秒内消失 ,并维持窦性心律 30～ 6 0min为即刻成功标准。结果　消融即刻成功率为 90 .5 % (38/ 4 2 ) ,其中右室流出道间隔部 94 .4 % (34/ 36 ) ,游离壁 6 6 .7% (4/ 6 )。 2 0例患者 2 4小时动态心电图记录消融前后室性期前收缩数分别为 (2 0 80 0± 10 4 0 )次 / 2 4h和 (110± 12 0 )次 / 2 4h(P <0 .0 0 1)。 1例患者消融术中出现室颤经电复律恢复窦性心律 ,其余无任何并发症。随访 4～ 16个月症状缓解率为 89.5 % (34/ 38) ,复发率为 5 .3% (2 / 38) ,均为右室流出道游离壁室性期前收缩。随访期间亦无并发症。结论　经导管射频消融可有效地治疗症状重、药     

Determinants of successful ablation of idiopathic ventricular tachycardias with left bundle branch block morphology from the right ventricular outflow tract

The aim of the study was to define the factors that may predict the outcomes of radiofrequency ablation from the right ventricular outflow tract (RVOT) in patients with idiopathic VT with a QRS morphology of LBBB. Endocardial mapping and RF ablation from the RVOT were performed in 35 patients (14 men, mean age 41 +/- 14 years), and VT was successfully ablated in 30 patients. There was no significant difference with regard to clinical characteristics and electrophysiological findings between patients with successful and failed ablation. The VTs with successful ablation showed an rS (n = 16) or QS (n = 14) pattern in lead V1, and all five VTs with failed ablation showed an rS pattern in lead V1. Although the absence of an R wave in lead V1 did not differ between patients with successful and failed ablation (P = 0.13), the absence of an R wave in lead V1 predicted VT successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 24%). The VTs with successful ablation had a median precordial transitional zone at lead V4 (range V3-V6), whereas all five VTs with failed ablation had precordial transition zones at lead V3 (P = 0.004). Furthermore, a presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 predicted VT not successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 100%). In conclusion, some VTs with LBBB and inferior or normal axis cannot be ablated from the RVOT. The presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 suggest that some VTs may not arise from the RVOT.     

Frequency of spontaneous and inducible atrioventricular nodal reentry tachycardia in patients with idiopathic outflow tract ventricular arrhythmias

OBJECTIVES: We sought to assess the frequency of spontaneous or inducible atrioventricular nodal reentry tachycardia (AVNRT) in patients referred for radiofrequency ablation (RFA) of idiopathic outflow tract ventricular arrhythmias. BACKGROUND: In patients with no obvious heart disease, AVNRT and outflow tract ventricular tachycardia (VT) are the most frequently encountered supraventricular and ventricular tachycardias, respectively. An increased coexistence of the two arrhythmias has been recently suggested. METHODS: In 68 consecutive patients referred for RFA of an idiopathic ventricular outflow tract arrhythmia, a stimulation protocol including repeated bursts of rapid atrial pacing, up to triple atrial extrastimuli during sinus rhythm and rapid ventricular pacing was performed before and after isoproterenol infusion following RFA of the ventricular arrhythmia. In patients with inducible AVNRT, RFA of the slow pathway was performed. RESULTS: Of the 68 study patients, 17 (25%) had either spontaneous AVNRT documented prior to RFA of the ventricular arrhythmia (n = 4) or inducible AVNRT at the time of RFA of the ventricular arrhythmia (n = 13). AVNRT was induced by atrial pacing in 15 (88%) of 17 patients: in 3 patients without isoproterenol and in 12 patients during isoproterenol infusion. Uncomplicated RFA of the slow pathway was successfully achieved in all patients with inducible AVNRT. CONCLUSION: Spontaneous or inducible AVNRT is relatively common in patients with idiopathic outflow tract ventricular arrhythmias. Atrial stimulation, especially when performed after isoproterenol infusion plays a major role in AVNRT inducibility. Although we performed RFA of the slow pathway in patients with inducible AVNRT and no prior tachycardia documentation, the question whether this is mandatory remains unsettled.     

Catheter ablation of ventricular tachycardia in structurally normal hearts

Ventricular tachycardia (VT) in patients without structural heart disease can be observed in 10% of patients presenting with ventricular arrhythmias. These VTs are characterized by QRS morphology, ventricular origin and their response to pharmacologic agents. It is essential to rule out structural heart disease in this population as this can significantly alter the management and the long-term prognosis. These VTs generally have a benign course and therapeutic options are aimed at relieving symptoms related to the arrhythmia. Medical therapy is effective in many patients and radiofrequency offers a cure to those who are refractory to medical therapy. Careful attention to the electrocardiogram can help localize the origin of the VTs, which is crucial when planning an ablation strategy.     

Localization of precise origin of idiopathic ventricular tachycardia from the right ventricular outflow tract by a 12-lead ECG: a study of pace mapping using a multielectrode "basket" catheter

Radiofrequency catheter ablation guided by pace-mapping techniques has proven effective in eliminating idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT). A method for rapidly identifying the origin of VT from 12-lead electrocardiogram (ECG) findings would be helpful for the catheter ablation procedure. The purpose of this study is to precisely localize the origin of idiopathic VT from the RVOT by a 12-lead ECG from a study of multipoint pace mapping. In one patient with premature ventricular complex (PVC) and 3 with VT, a "basket" catheter was deployed in the RVOT for bipolar pacing from 56 sites in the endocardium of RVOT. Under fluoroscopy the pacing sites were classified into the septum and free wall. We investigated the QRS morphology in leads, I, II, and III; the depth of the QS wave in leads aVR and aVL; and the height of the initial r wave in leads V1 and V2. Pacing was captured in 30-47 of 56 sites (54%-84%). As the pacing sites changed from the anterior to posterior of the septum, the QS notch (-) type in lead I shifted through rs to R, while a shift from R type to rR' or Rr' was noted in leads II and III. As the pacing sites changed from the anterior to posterior of the free wall, lead I showed a shift from the QS notch (+) type to R, while a shift from rR' to Rr' (or rR' unchanged) was found in leads II and III. The depth of the QS wave in leads aVR and aVL showed a tendency for aVR to be deeper than aVL toward the posterolateral attachment of both the septum and free wall, whereas aVL tended to be deeper than aVR toward the anterior attachment. The initial r waves in V1 and V2 became greater as the pacing site was positioned at a higher or more posterior location. These findings may provide more precise and clinically useful diagnostic information on the site of the origin of idiopathic VT originating from the RVOT by a 12-lead ECG.     

Role of the notched unipolar electrogram in guiding catheter ablation of frequent premature ventricular contractions originating from the ventricular outflow tract

ObjectiveTo investigate the value of a notched unipolar electrogram (N-uniEGM) in confirming the origin of premature ventricular contractions originating from the ventricular outflow tract (VOT-PVC) during mapping and ablation procedures.MethodsThis retrospective study enrolled consecutive patients with symptomatic idiopathic frequent VOT-PVCs that underwent radiofrequency ablation. The characteristics of the uniEGM of the successful ablation targets were analysed. N-uniEGM was defined as the uniEGM presenting a QS morphology with ≥1 steep notches on the downstroke deflection. All patients were followed-up for 3 months post-ablation.ResultsThe study enrolled 190 patients with a mean ± SD age of 49.0 ± 15.3 years. N-uniEGMs were recorded in 124 of 190 (65.3%) patients. The N-uniEGM distribution area was limited to a mean ± SD of 0.8 ± 0.4 cm². N-uniEGM showed consistency with the outcomes of activation mapping and pace mapping. Patients with an N-uniEGM had an ablation success rate of 98.4% (122 of 124) and their ablation times were significantly shorter than those without an N-uniEGM (7.6 ± 3.8 s versus 15.8 ± 8.8 s, respectively). The sensitivity and specificity of N-uniEGM in predicting successful ablation of VOT-PVCs were 72.6% and 91.7%, respectively.ConclusionN-uniEGM was a highly specific and moderately sensitive predictor of successful radiofrequency ablation in patients with VOT-PVCs.