Radiofrequency Catheter Ablation of Ventricular Tachycardia Following Implantation of an Automatic Cardioverter Defibrillator

The present study reports on the complementary role of two nonpharmacological options of antiarrhythmic therapy. Background: Catheter ablation, antitachycardia surgery, and the implanfahie cardioverter de/ibrillator (ICD)have become important tools in the management of ventricuiar tachyarrhythmias. However, the emergence of ventricuiar tachyarrhythmias after implantation of an ICD is possihie because the arrhythmogenic suhstrate is not affected. Patients and Methods:Six of 180 patients developed frequent episodes of monomorphic ventricular tachycardia (n = 2) or incessant ventricular tachycardia (n = 4) following implantation of an ICD and underwent radio/requency (RF)catheter ablation. Catheter ablation was performed using a HF generator HAT 200. Energy was delivered between a 4-mm tip electrode of the ahiation catheter and a patch electrode. Results: Catheter ablation was done 6.8 ± 5 months following ICD implantation; 6 ± 2.2 RF impulses were delivered at the site of origin of ventricuiar tachycardia chararcterized by early endocardial activation during ventricular tachycardia, identical pace mapping and long latency between stimulus, and QRS-complex in five patients. New bundle branch reentry was the underlying mechanism of ventricular tachycardia in one patient. RF catheter ablation resulted in termination o/ incessant ventricular tachycardia. Immediately postabiation, the documented ventricular tachycardia was rendered noninducible in all patients. No ICD malfunctions have been observed. One patient died due to heart failure 24 hours after successful ablation of the incessant ventricular tachycardia. During a follow-up of 5–19 months, episodes of ventricular tachycardia recurred in four patients. All episodes could be controlled by the ICD without frequent cardioversions. Conclusion: RF catheter ablation is o complementary therapeutic option in case of frequent or incessant ventricular tachycardia after ICD implantation.     

特发性室性心动过速射频导管消融方法探讨

目的：探讨特发性室性心动过速（IVT）的消融方法。方法：对12例IVT患者进行射频消融治疗，源于右心室IVT采用消融导管起搏标测法，以起搏时与VT发作时的12导联心电图QRS波形态与振幅完全相同的起搏部位为消融靶点。并在周围做巩固消融，起源于左心室IVT以激动标测法或寻找P电位。结果：IVT消融成功率91．6％（11／12），1例ILVT在第3次复发射频消融后发生双束支阻滞而安装了VVI永久起搏器。结论：起源于左心室的IVT宜采用激动顺序标测法，起源于右心室的IVT宜采用起搏标测法。对有效靶点周围进行线状或环状消融，有利于提高手术成功率。     

Ventricular tachycardia--etiology, mechanisms and therapy

Prevention and therapy of cardiovascular diseases have undergone enormous changes over the last decades. However, ventricular tachycardias (VT) still pose a major problem in a number of cardiac patients. Analysis of the etiology and mechanism of the tachycardia is of paramount importance for initiation of specific therapies. The morphology of VTs on the surface ECG can be either polymorphic or monomorphic. Polymorphic VTs have a constantly changing QRS-morphology due to the variable ventricular activation, without specific origin. This kind of VT is mainly caused by an acute, often reversible condition, such as ischemia or QT-prolongation. These VTs are potentially malignant, they cannot be treated by catheter ablation. In contrast, monomorphic VTs have a constant QRS-morphology, indicative of repetitive ventricular depolarisation in the same activation sequence. This kind of VT is either caused by focal abnormal activity (triggered activity, automaticity, micro-reentry) or by an arrhythmogenic substrate (macro-reentry). Focal idiopathic VTs usually have a benign prognosis and catheter ablation is potentially curative. The majority of ventricular arrhythmias, however, are substrate-related reentry tachycardias, most commonly based on an infarct scar Therapy of first choice for these patients is the treatment with an implantable Cardioverter/Defibrillator (ICD). Catheter ablation is indicated in case of drug refractory recurrent VTs triggering repeated ICD therapies. The different therapeutic strategies are not alternative but complementary options in many patients.     

Results of Catheter Ablation of Ventricular Tachycardia Using Direct Current Shocks

Thirty-three patients with recurrent ventricular tachycardia (VT) underwent catheter ablation with direct-current shocks. One to four shocks of 100–300 joules were delivered to the presumed VT exit sites as identified by endocardial mapping and pace mapping. Fifteen patients (45%) had no recurrence of symptomatic VT during a follow-up interval of 15.5 ± 10 months (mean ± standard deviation). Five patients experienced six nonfatal complications (new VT or ventricular fibrillation, transient neurological deficit, atrioventricular block, brachial artery thrombosis). In conclusion, catheter ablation in selected patients with recurrent VT has the potential for preventing recurrences of VT over the long-term and is relatively safe.     

Ventricular fibrillation/tachycardia

Ventricular fibrillation and rapid ventricular tachycardia called as pulseless tachycardia are both fetal and need immediate therapy to respore sinus rhythm. Sustained monomorphic ventricular tachycardia is also known to have a poor prognosis. Diagnosis of these arrhythmias should be followed by electrophysiologic study for risk stratification. The efficacy of the antiarrhythmic drug therapy is known to be limited. Catheter ablation can cure the arrhythmia but the success rate is limited: 50-70% in selected patients. Though symptomatic, ICD is the most reliable therapy so far. Antiarrhythmic drugs or catheter ablation should be tried as adjunctive therapy in fatal ventricular arrhythmias.     

Radiofrequency ablation of the ventricular tachycardia with arrhythmogenic right ventricular cardiomyopathy using non-contact mapping

BACKGROUND: Intracardiac non-contact mapping provides a rapid and accurate isopotential mapping that facilitates catheter ablation of the ventricular tachyarrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC). METHODS: Thirty-two consecutive patients (26 men and 6 women, mean 37.2 +/- 13.8 years) were treated with ablation. Fourteen patients had a history of syncope/pre-syncope. Two patients had an implantable cardiac defibrillator (ICD) previously implanted. RESULTS: There were 67 ventricular tachycardias (VTs) induced in the 32 patients. The average VT rate was 210 +/- 32.2 (130-310) bpm. There were 42 episodes of VT that had a heart rate > or =200 bpm and 24 of the 32 patients (75%) had > or =2 morphologies of VT. Regional ablation was applied by targeting the earliest VT activation sites under the guidance of non-contact mapping. Acute success was achieved in 84.4% (27/32) patients, and significant improvement was seen in 15.6% (5/32) patients as evidenced by a slower rate of VT. None of the patients experienced syncope/pre-syncope or sudden death during the 28.6 +/- 16 (9-72) month follow-up. There were no complications of the procedure. At the end of follow-up, 81.3% of the patients were free of VT without medication while the rest of the patients achieved a modified success. CONCLUSIONS: The rapid ventricular tachyarrhythmias in ARVC patients can be abolished or improved significantly by regional RF catheter ablation under the guidance of non-contact mapping. There was no sudden cardiac arrest or death in those patients without ICD implantation. Delayed efficacy may occur in some patients after ablation.     

Changing Trends in Therapy Delivery with a Third Generation Noncommitted Implantable Defibrillator: Results of a Large Single Center Clinical Trial

Thirty-four patients underwent implantation of a third generation ICD, the 4210 ATP, for sudden cardiac death or ventricular tachycardia. This device incorporates significant telemetry logs as well as a detailed analysis of each arrhythmia episode detected. During the period of clinical follow-up, a mean of 12.2 months, a total of 26,569 VT or VF detections were made. The vast majority of these were either due to atrial fibrillation, nonsustained VT, or "noise" detection, and only 6% led to device therapy. ATP was successful in 86.3% of episodes, with 3.5% accelerations and 2.4% failure of ATP trains. The majority of inappropriate therapy episodes were clustered in seven patients, and all were easily diagnosed with the aid of the extensive telemetry Jogs and sense histories. Of five late deaths, three were from congestive heart failure, one from cerebrovascular accident, and one unknown. These data reveal that this "tiered" therapy noncommitted ICD performs to expectations; the stored data is of significant value in diagnosing the cause of ICD therapy. In addition, ATP is an effective modality for termination of VT.     

Catheter Ablation versus Standard Conventional Treatment in Patients with Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE-AF) - Study Design

Background: Electrical isolation of the pulmonary veins by catheter ablation is an emerging treatment modality for the treatment of atrial fibrillation (AF) and is increasingly used in patients with heart failure.
Methods: The catheter ablation versus standard conventional treatment in patients with left ventricular dysfunction and atrial fibrillation trial (CASTLE-AF) is a randomized evaluation of ablative treatment of atrial fibrillation in patients with left ventricular dysfunction. The primary endpoint is the composite of all-cause mortality or worsening of heart failure requiring unplanned hospitalization using a time to first event analysis. Secondary endpoints are all-cause mortality, cardiovascular mortality, cerebrovascular accidents, worsening of heart failure requiring unplanned hospitalization, unplanned hospitalization due to cardiovascular reason, all-cause hospitalization, quality of life, number of therapies (shock and antitachycardia pacing) delivered by the implantable cardioverter-defibrillator (ICD), time to first ICD therapy, number of device-detected ventricular tachycardia and ventricular fibrillation episodes, AF burden, AF free interval, left ventricular function, exercise tolerance, and percentage of right ventricular pacing. CASTLE-AF will randomize 420 patients for a minimum of 3 years at 48 sites in the United States, Europe, Australia, and South America.     

Ventricular Tachycardia/Fibrillation: Therapeutic Alternatives

It is now clear that no single therapy is appropriate for a consecutive series of patients with ventricular tachycardia or ventricular fibrillation (VT/VF). Drug responders by electrophysiological studies, patients who are not inducible following surgery, and patients treated with an implantable cardioverter defibrillator (ICD) all can have similarly low sudden death rates and virtually identical long-term mortality. However, many patients fail to respond to drugs, and surgical risks are excessive in others, and always higher than for an ICD implant. Nevertheless, overall survival in each of these groups (and probably for patients treated with antitachycardia pacers and ablation) is about 60% at 60 months. Major challenges now are: (1) choosing therapy to maximize risk-benefit ratio; and (2) treatment of the pump failure and progressive disease that now accounts for most cardiac mortality.     

Recent advances in radiofrequency catheter ablation

Radiofrequency catheter ablation has been established as a first-line treatment of various paroxysmal tachycardias, and its developments are still ongoing. As recent advances of radiofrequency catheter ablation, we can point out the following issues: 1) transaortic approach for idiopathic ventricular tachycardia(VT) of LBBB-form with inferior axis, 2) new approach guided by mid-diastolic potential for verapamil-sensitive VT, 3) pulmonary vein(PV) isolation technique guided by PV ostial circular electrogram mapping for paroxysmal atrial fibrillation, 4) new ablation strategies for macro-reentry tachycardia such as incisional atrial tachycardia and VT post old myocardial infarction guided by electro-anatomical mapping, and 5) cooled-tip ablation technique for atrial flutter and VT resistant to conventional system.     

导管消融减少植入式心脏转复除颤器放电治疗的Meta分析

目的 评估对于曾有急性心肌梗死的室性心动过速(VT)患者,导管消融(RA)减少植入式心脏转复除颤器(ICD)放电转律治疗的疗效和安全性.方法 计算机检索Pubmed、EMbase、Cochrane图书馆、中国生物医学文献光盘数据库、中文科技期刊全文数据库、CNKI数字图书馆,纳入RA+ICD和单独使用ICD对比治疗VT...     

心房颤动射频消融术中出现规律性快速性房性心律失常的预测因素

目的：分析心房颤动（简称房颤）经导管射频消融术中出现心房扑动、房性心动过速等规律性快速性房性心律失常（RATs）的预测因素。方法：首次行经导管射频消融治疗的497例房颤患者（阵发性房颤333例,持续性和（或）永久性房颤164例）在三维标测系统及环状标测电极导管指导下行经导管射频消融治疗（包括环肺静脉电隔离、线性消融和（或）碎裂电位消融）。术中记录RATs的发生情况,并分析RATs的可能影响因素。结果：术中共有163例患者[32．8％;阵发性房颤92例,持续性和（或）永久性房颤71例]出现195种RATs,持续性和（或）永久性房颤术中RATs的发生率显著高于阵发性房颤（43．3％比27．6％,P〈0．001）。单因素分析发现心脏外科术后（P〈0．001）、术前有RATs（P=0．010）、持续性和（或）永久性房颤（P〈0．001）、左房内径增大（P〈0．001）、左室射血分数降低（P=0．018）是房颤术中出现RATs的影响因素。Logistic多因素回归分析发现心脏外科术后[优势比（0R）=8．14,95％可信区间（CI）：I．69～39．1,P=0．0093、术前有RATsEOR=2．15,95％CI：1．35～3．42,P=0．001]、持续性和（或）永久性房颤[0R=1．71,95％CI：1．06～2．76,P=0．029]、左房内径[0R=1．04,95％CI：1．01～1．08,P=0．025]是术中出现RATs的独立预测因素。结论：房颤射频消融术中常出现RATs,心脏外科术后、术前有RATs、持续性和（或）永久性房颤、左房内径是术中出现RATs的独立预测因素。     

Two Cases of Ventricular Parasystole Associated with Ventricular Tachycardia

In two patients, ventricular pamsystole (VP) was associated with ventricular tachycardia (VT), and in one patient, catheter ablation was successful. In patient 1, with dilated cardiomyopathy, VP led to VT, which converted to ventricular fibrillation. In patient 2, VP led to symptomatic nonsustained polymorphic VT. The origin of parasystolic focus was determined byendocardial mapping, and a radiofrequency current was delivered to patient 2. Both VP and VT disappeared immediately, and no recurrence has been observed during a follow-up of 8 months. Catheter ablation to the parasystolic focus was effective and a relationship between VP and VT was strongly suggested.     

Electroanatomically guided catheter ablation of ventricular tachycardias causing multiple defibrillator shocks

With conventional techniques, RF catheter ablation is difficult in patients with unstable VT or with multiple VTs. The feasibility of RF catheter ablation guided by three-dimensional electroanatomic mapping technique in patients whose implanted ICD continued to deliver multiple shocks due to VT despite use of antiarrhythmic medications was assessed in 19 patients (15 men, 4 women; mean age [+/- SD] 70+/-7 years). All had a prior history of MI and subsequently had received an ICD due to VT. During the 12-week preablation period, these patients received 31+/-15 shocks (range 4-62 shocks) due to refractory monomorphic VTs. An electroanatomic mapping technique using the CARTO system was performed to delineate scar tissue. RF catheter ablation was then performed at appropriate sites identified by pace mapping and by substrate mapping. Seventeen patients were on amiodarone at the time of ablation. Twenty-seven VTs were documented clinically, and 45 were induced during electrophysiological evaluation. Of the 45 tachycardias induced, 38 VTs were targeted for ablation. Catheter ablation was performed during sinus rhythm in 31 episodes and during VT in 7 episodes. During a mean follow-up of 26+/-8 weeks (range 18-48 weeks), 13 (66%) patients had no recurrence of VT (P < 0.0001) and antiarrhythmic drugs were discontinued or the number of medications reduced in 17 patients (P < 0.0001). Electroanatomic mapping is helpful in identifying sites for catheter ablation in highly symptomatic patients with refractory VT associated with myocardial scarring.     

Inappropriate detection of supraventricular arrhythmias by implantable dual chamber defibrillators: a comparison of four different algorithms

Inappropriate therapy of supraventricular tachyarrhythmias by an ICD is still a common problem. Dual chamber (DDD) ICDs provide additional atrial sensing and should result in higher specificity for detection of supraventricular tachyarrhythmias. However, a direct comparison of different dual chamber algorithms has not been reported. The detection algorithms of four different DDD ICDs were tested: Phylax AV, Defender IV, Ventak AV III DR, and Gem DR 7271. Based on arrhythmias recorded from patients undergoing invasive electrophysiological studies and in many cases of catheter ablation at our institution, a library consisting of 71 supraventricular and 15 ventricular tachyarrhythmias was created. The library consists of episodes of atrial fibrillation, atrial flutter with different AV conduction, typical and atypical AV nodal reentrant tachycardia, AV reentrant tachycardia, sinus tachycardia, and ventricular tachycardia with and without ventriculoatrial conduction. Atrial fibrillation was appropriately classified by all four algorithms. However, the specificity for detection of other supraventricular tachyarrhythmias achieved by the Biotronik (12%) and the Guidant (11%) devices was significantly lower compared to the specificity of the ELA (28%) and the Medtronic DDD ICD (20%). This is due to the fact that the Biotronik and the Guidant algorithm classified all supraventricular tachyarrhythmias resulting in a stable ventricular rate as ventricular tachycardia, whereas the ELA and Medtronic algorithms performed a more detailed analysis by assessment of PR association, atrial onset, or timing of the atrial event relative to the ventricular event, respectively. Atrial fibrillation, the most common supraventricular tachyarrhythmia in patients with ICD, was detected by all devices.     

Reinitiation of ventricular macroreentry within the His-Purkinje system by back-up ventricular pacing - a mechanism of ventricular tachycardia storm

BACKGROUND: We describe immediate reinitiation of macroreentry ventricular tachycardia (VT) involving the His-Purkinje system by ventricular pacing from the electrode of an implantable cardioverter defibrillator (ICD) as a mechanism of VT storm refractory to ICD therapy. METHODS AND RESULTS: Repetitive reinitiation of bundle branch reentry tachycardia (BBRT), interfascicular tachycardia, or both VTs by ventricular pacing was identified in four ICD patients presenting with VT storm or incessant VT. All patients had a pre-existing prolonged HV interval (75 +/- 9 ms) and left bundle branch block (LBBB) or bifascicular block during sinus rhythm. The VTs included BBRT with LBBB in three patients and interfascicular tachycardia with right bundle branch block (RBBB) and left anterior or left posterior fascicular block in two patients. The paced beats from the ICD electrode exhibited a LBBB pattern of depolarization in two patients and a RBBB contour in V1 and V2 with left axis deviation in two patients. The QRS complex during pacing from the ICD electrode closely resembled that of the recurrent VT in all four patients suggesting that the pacing site of the ICD electrode was in proximity to the myocardial exit site of the bundle fascicle used for antegrade conduction during the reinitiated VT. Ventricular pacing from the ICD electrode after termination of the VT apparently encountered the retrograde refractoriness of this bundle fascicle and allowed immediate re-propagation of the wavefront orthodromically along the VT circuit. BBRT was eliminated by ablation of the right bundle branch. Successful ablation of the interfascicular tachycardias was achieved by targeting (1) an abnormal potential of the distal left posterior Purkinje network or (2) a diastolic potential during VT in the midinferior left ventricular (LV) septum. CONCLUSIONS: Repetitive reinitiation of BBRT and interfascicular tachycardia by ventricular pacing from the ICD electrode should be considered as a mechanism of VT storm refractory to ICD therapy in patients with a pre-existing conduction delay within the His-Purkinje system.     

Worldwide Clinical Experience with aDown-Sized Active Can ImplantableCardioverier Defibrillator in 162 ConsecutivePatients

Treatment with an ICD is the first-line treatmentfor survivors of sudden cardiac death. More recently, evidence accumulates that prophylactic ICD therapy may be beneficial for selected subgroups of patients after myocardial infarction. Particularly for future studies on the value of prophylactic ICD therapy, downsized devices are needed to allow easy pectoral implantation with a single lead configuration and featuring extended memory capabilities.Accordingly, this study assesses the clinical performance of a downsized fourth-generation ICD in 162consecutive patients. All devices could be successfully implanted pectorally, in 96% with a single leadconfiguration with a low defibrillation threshold of 10.6 ± 5.2 J. During a 3-month follow-up, 26% of thepatients received ICD therapy. Twenty percent had appropriate therapy for ventricular fibrillation (n= 9) and VT (n = 23), which was effective in all cases. Of the 450 episodes of VT, 426 were terminated by an-titachycardia pacing. Fourteen patients (9%) had inappropriate ICD therapy mainly due to atrial fibrillation or sinus tachycardia, which could be reliably diagnosed by the ICD stored intracardiac electrograms.     

Results of Delivered Therapy for VT or VF in Patients with Third-Generation Implantable Cardioverter Defibrillators

Third-generation implantable cardioverter defibrillators (ICDs) offer tiered therapy and can provide significant advantage in the management of patients with life-threatening arrhythmias. Three different types of ICDs were implanted in 21 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia presentation was VT(76%), VF(10%), or both (14%). The mean left ventricular ejection fraction for the group was 32.4 ± 7%. No surgical mortality occurred. Prior to discharge individual EPS determined the final programmed settings of the ICDs. During a mean follow-up of 13 ± 1.4 months (range 2–20) the overall patient survival was 85.7%. No sudden arrhythmic or cardiac death occurred. Twenty of 21 patients (95%) received therapy by their device. In 14 patients (67%) antitachycardia pacing (A TP) was programmed "on," 13 of which was self-adaptative autodecremental mode. There were 247 VT episodes, 231 of which were subjected to ATP with 97% success and 3% acceleration or failure. Low energy shocks reverted all other VT episodes. VF episodes were successfully reverted by a single shock (93%), two shocks (6%), or three shocks (1 %). We conclude that ATP therapy of VT is successful in the large majority of episodes with rare failures, and that VF episodes are generally terminated by a single ICD shock.     

Delayed papillary muscle rupture after radiofrequency catheter ablation: A case report

BACKGROUNDWith an increased number of surgical procedures involving the mitral annular region, the risk of mitral valve prolapse (MVP) has also increased. Previous studies have reported that worsening of MVP occurred early after radiofrequency catheter ablation (RFCA) at papillary muscles in ventricular tachycardia (VT) patients with preoperative MVP. CASE SUMMARYWe report a case where MVP and papillary muscle rupture occurred 2 wk after RFCA in a papillary muscle originated VT patient without mitral valve regurgitation or prolapse before. The patient then underwent mitral valve replacement with no premature ventricular contraction or VT. During the surgery, a papillary muscle rupture was identified. Pathological examination showed necrosis of the papillary muscle. The patient recovered after mitral valve replacement. CONCLUSIONToo many ablation procedures and energy should be avoided.     

Activation of the Right Ventricular Apical Electrogram during Ventricular Tachycardia: Suitahility for Synchronizing Intracavitary Cardioversion

An intravascular catheter positioned in the right ventricular apex has been used for intracavitary cardioversion in patients with recurrent ventricular tachycardia. We examined the timing of the right ventricular apical electrogram during sinus rhythm and ventricular tachycardia (VT) in order to determine if this signal could be used to synchronize the delivery of a countershock. Sixty-three distinct morphologies of VT were observed in 33 patients undergoing electrophysiologic testing with programmed stimulation. Regardless of VT morphology or site of origin, the bipolar right ventricular electrogram always occurred within the peripheral QRS complex during ventricular tachycardia. Relative timing occurred within the QRS ranging from the initial 13% of the QRS to the last 12%. When all episodes of VT were examined, the timing of the right ventricular electrogram did not correlate linearly with the peak of the ECG, but the right ventricular electrogram occurred within 60 ms of the peak ECG in 83% of episodes of ventricular tachycardia. In one case of arrhythmogenic right ventricular dysplasia, the right ventricular electrogram occurred 160 ms after the peak ECG in ventricular tachycardia, a time when delivery of a countershock may have precipitated ventricular fibrillation. Six of these patients underwent cardioversion utilizing an intracavitary catheter and external generator. Acceleration of VT, or conversion to ventricular fibrillation, occurred following two of 27 shocks (7.4%). The right ventricular electrogram occurred the latest within the QRS complex in the two patients who developed acceleration of the tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)