Radiofrequency Catheter Ablation of Frequent Monomorphic Ventricular Ectopic Activity

INTRODUCTION: Frequent ventricular ectopic beats can result in severe symptoms and may even be incapacitating in some patients. Although radiofrequency catheter ablation is an effective and safe therapy for drug refractory idiopathic ventricular tachycardia, it has not been widely used in ventricular ectopy. The purpose of this study was: (1) to assess the potential role of catheter ablation in eliminating monomorphic ventricular ectopy in symptomatic patients regarding feasibility and safety and (2) to determine the usefulness of various mapping strategies. METHODS AND RESULTS: Forty-one patients with symptomatic ventricular ectopic activity (right ventricular origin in 23 patients, left ventricular origin in 18 patients) were enrolled. The mean frequency of ventricular ectopic beats was 1512+/-583/hour documented by Holter ECG monitoring. These patients had previously been unable to tolerate or had been unsuccessfully treated with a mean of 3+/-1 antiarrhythmic agents. The site of origin was mapped using earliest endocardial activation times, unipolar electrograms and pace mapping. Radiofrequency ablation was successful in 34 (83 %) of 41 patients. Multivariate logistic regression analysis revealed pace mapping as the only independent predictor for a successful ablation site (P < 0.01). After a follow-up of 3 months, the overall success rate was 71%. The mean frequency of ventricular ectopic beats after successful ablation was 12+/-10 ventricular premature beat/hour. CONCLUSION: Radiofrequency catheter ablation is an effective and safe treatment for frequent symptomatic drug refractory monomorphic ventricular ectopic activity. Pace mapping predicts best successful ablation of ventricular ectopic beats.     

应用射频消融术治疗右室流出道频发室性早搏的疗效观察

目的评价经导管射频消融治疗频发单形性右室流出道室性早搏的方法和疗效。方法选择28例症状重、右室流出道室性早搏患者进行射频消融治疗。所有患者均无器质性心脏病,24h动态心电图（Holter）确定RVOT频发单形性室性早搏≥10000次／24h。采用起搏标测和激动顺序标测,前者以起搏标测诱发的QRS波与室性早搏QRS波形态完全相同为消融靶点,后者以早搏时最早心室激动点为消融靶点。其中26例起源于右室流出道间隔部,2例起源于右室流出道游离壁。结果消融即刻成功率92．9％（26／28）,其中右室流出道间隔部92.3％（24／26）,游离壁100％（2／2）。患者24h动态心电图记录消融前、后室性期前收缩分别为（16206±2030）次／24h和（100±110）次／24h,P〈0．01。随访6-20个月,1例复发,再次消融成功。结论经导管射频消融可有效治疗症状重、药物治疗无效或不能耐受的单形性右室流出道室性早搏。     

射频消融治疗右室流出道频发单形性室性早搏的体会

目的　探讨射频消融治疗右室流出道频发室早的意义。方法　右室流出道频发单形性室性早搏病人2 8例。无心脏病史。ECG确定为右室流出道频发单形性室性早搏 (10 /min)。采用激动标测法 ,以自发单形性室性早搏V波最提前处为靶点消融。结果　即刻成功率 10 0 % (2 8/2 8)。术前与术后 2周 2 4h动态心电图监测 ,单形性室性早搏数 15 ,836～ 32 ,4 19/2 4h(术前 ) :0～ 1,2 36 /2 4h(术后 )。随诊 6～ 2 4个月 ,2 8例病人均已恢复正常生活 ,无并发症发生。结论　射频消融治疗右室流出道频发单形性室性早搏安全、有效。     

室性早搏的经导管射频消融评价

评价单形室性早搏 (简称室早 )经导管射频消融治疗的有效性和安全性。对 97例症状严重的正常心脏室早患者进行了导管射频消融 ,男 38例、女 5 9例 ,年龄 46 .2± 7.1岁。采用起搏标测和激动顺序标测 ,前者以起搏时与室早QRS波形态完全相同点为消融靶点 ,后者以早搏时最早心室激动点为消融靶点。 97例室早全部起源于心室流出道 ,右室流出道室早 95例 ,全部呈左束支阻滞形态 ;左室流出道室早 2例 ,QRS波均呈右束支阻滞形态 ,其中 1例V1导联呈Rs形态 ,1例呈rsr′形态。消融即刻成功率 95 .9% (93/ 97) ,2 4h动态心电图记录消融前后室早数为 2 0416± 1891次 / 2 4h和 12 2± 140次 / 2 4h(n =19,P <0 .0 0 1)。所有病人无任何并发症。随访 19± 6月未服用任何抗心律失常药物的症状消除率为 91% ,复发率是 4.3% (4/ 93) ,随访期间亦无不良反应和并发症发生。结论 :经导管射频消融可有效而安全地消除正常心脏单形室早 ,可作为症状严重、药物治疗无效或不能耐受患者的治疗选择     

Treatment of catecholamine-sensitive right ventricular tachycardia by endocardial catheter ablation.

Endocardial catheter ablation with direct current high voltage shocks was performed in a patient with recurrent syncope due to a catecholamine-sensitive ventricular tachycardia that was drug refractory and occurred in the absence of identifiable heart disease. Pace mapping and catheter activation mapping of the spontaneous and isoproterenol-induced ventricular tachycardia located the tachycardia origin in the right ventricular outflow tract. Ablation dramatically reduced spontaneous ventricular tachycardia and ectopic activity (from 50,000 to less than 100 ectopic beats/24 h). The patient has remained symptom free and without ventricular tachycardia recurrence for 3 years. These observations and review of previous studies suggest that catheter mapping can easily locate the arrhythmia focus in the right ventricular outflow tract and that catheter ablation can be performed at low risk. Catheter ablation is a viable option for the treatment of right ventricular catecholamine-sensitive tachycardias that are unresponsive to antiarrhythmic drugs.     

Rate control vs. pulmonary vein isolation

Atrial fibrillation (AF) is a frequent arrhythmia encountered in clinical practice. It can be asymptomatic in some patients but incapacitating in others. Regardless of symptoms, patients at increased risk of embolism need chronic anticoagulation. In patients with AF and a rapid ventricular response that cannot be controlled with drugs, interventional procedures are required. Radiofrequency catheter ablation of the atrioventricular junction with pacemaker implantation is an effective therapeutic approach that relieves the symptoms associated with a rapid and irregular rhythm. This approach can also improve left ventricular function in patients with tachycardia-induced cardiomyopathy. Due to the irreversible nature of this approach, it is more suitable for older patients and those with advanced left ventricular dysfunction. Many patients with a structurally normal heart have symptomatic paroxysmal AF refractory to antiarrhythmic agents. This form of AF is frequently initiated by premature atrial beats arising from the pulmonary veins. A catheter ablation technique is available to electrically isolate the pulmonary veins. This procedure can eliminate AF in many patients but can result in complications, including embolic events, pulmonary veins stenosis, and cardiac perforation.     

经导管射频消融治疗流出道起源室性期前收缩临床观察

目的探讨经导管射频消融治疗流出道起源室性期前收缩的方法和疗效。方法回顾性分析36例流36例起源室性期前收缩患者行射频消融治疗的临床资料，着重分析射频消融治疗的方法、结果及随访观察。结果36例患者中35洌消融治疗后期前收缩完全消失．成功率97．2％（35／36），其中11例患者合并器质性心脏病，存行经导管射频消融治疗后症状明显改善。手术时间为（77．1±18．3）min，消融时间（356．4±127．4）s，术中、术后无并发症．随访6个月，1例复发，复发率2．9％（1／35）．结论经导管射频消融治疗心事流叶道室性期前收缩的成功率高、安全性好、手术并发症少，远期效果较好．对合并器质性心脏病的患者也可选择行射频消融治疗.     

Endocardial mapping of right ventricular outflow tract tachycardia using noncontact activation mapping

INTRODUCTION: Activation mapping and pace mapping identify successful ablation sites for catheter ablation of right ventricular outflow tract (RVOT) tachycardia. These methods are limited in patients with nonsustained tachycardia or isolated ventricular ectopic beats. We investigated the feasibility of using noncontact mapping to guide the ablation of RVOT arrhythmias. METHODS AND RESULTS: Nine patients with RVOT tachycardia and three patients with ectopic beats were studied using noncontact mapping. A multielectrode array catheter was introduced into the RVOT and tachycardia was analyzed using a virtual geometry. The earliest endocardial activation estimated by virtual electrograms was displayed on an isopotential color map and measured 33 +/- 13 msec before onset of QRS. Virtual unipolar electrograms at this site demonstrated QS morphology. Guided by a locator signal, ablation was performed with a mean of 6.9 +/- 2.2 radiofrequency deliveries. Acute success was achieved in all patients. During follow-up, one patient had a recurrence of RVOT tachycardia. Compared with patients (n = 21) who underwent catheter ablation using a conventional approach, a higher success rate was achieved by noncontact mapping. Procedure time was significantly longer in the noncontact mapping group. Fluoroscopy time was not significantly different in the two groups. CONCLUSION: Noncontact mapping can be used as a reliable tool to identify the site of earliest endocardial activation and to guide the ablation procedure in patients with RVOT tachycardia and in patients with ectopic beats originating from the RVOT.     

右室流出道室性早搏的导管消融治疗

目的　探讨右室流出道频发单形性室性早搏行射频导管消融治疗的可行性和有效性。方法　对 11例无器质性心脏病右室流出道频发单形性室性早搏患者进行射频导管消融 ,采用起搏标测 ,以起搏时与自发室早QRS波群图形完全相同的点为消融靶点。结果　消融即刻成功率 91% (10 / 11) ,所有患者无任何并发症 ,随访 1～ 30个月 ,无迟发并发症发生 ,无室早复发。结论　右室流出道频发单形性室性早搏予射频导管消融治疗有效、安全 ,具有可行性。     

右室流出道室性早搏的射频消融治疗

目的探讨射频消融治疗右室流出道室性早搏的方法和疗效。方法选择52例右室流出道室性早搏患者进行射频消融法治疗,男28例,女24例,年龄15~67岁,平均45.1岁;病史3~14年,平均6.8年均有明显症状,但无器质性心脏病的证据。多种抗心律药物治疗无效,心电图显示室性早搏均呈左束支阻滞图形,Ⅱ、Ⅲ、AVF导联为高大的R波。采用起搏标测。结果即刻成功率94%(49/52)。术前与术后1周24h动态心电图检查室性早搏为(11250~37460)次/24h和(0~1120)次/24h,两者间差异(P<0.01)。随访2~32个月,无复发。结论无器质性心脏病顽固性右室流出道室早的导管射频消融是一种安全可靠的方法。     

反复无休止室性心动过速的动态心电图监测与研究

目的探讨反复无休止室性心动过速（室速）的动态心电图（dynamic electrocardiogram,DCG）特点。方法收集昆明医科大学第二附属医院确诊为无休止性室速18例患者的DCG资料,根据临床诊断、心内电生理、DCG的室速特点,将患者分为两组：特发性室速（IVT）组共10例,年龄（45.00±12.83）岁;心肌病组共8例,年龄（58.86±11.39）岁。所有患者行24 h DCG监测,对室速发作总的时间、阵次、室性心搏数,频率及QRS波形态进行分析研究。结果所有患者在室速发作中持续时间占总监测时间的11.2%～30.5%;室速心搏次数占总心搏的13.2%～26.4%。IVT组中室速起源于右心室流出道7例,左心室流出道2例,左后间隔分支区域1例。与心肌病组比较,IVT组年龄偏轻,室速发作时心室率偏慢,差异有统计学意义（P〈0.05）;且室速持续时间长。IVT组最长一阵室速发生持续时间〉30 s有8例（80%）,扩张型心肌病组无1例发生。结论根据12导联DCG室速发作时间长短,可对反复无休止室速进行诊断,且通过室速发作时QRS波特点可初步判断其起源部位,对指导临床,尤其是射频消融治疗起到一定的作用。     

Atrial flutter and atrial fibrillation: which relationship? New insights into the electrophysiological mechanisms and catheter ablation treatment.

Atrial fibrillation (AF) and atrial flutter (AFL) are two arrhythmias commonly associated in clinical practice. This association generally reflects a similar arrhythmogenic substrate. It has been observed that the development of isthmus-dependent AFL is often preceded by AF. The conversion from AF to AFL develops thanks to a line of functional block in the right atrial free wall. In this subset a particular condition is represented by typical AFL that occurs during the treatment with class IC or III antiarrhythmic drugs in patients with previous AF. A hybrid approach (antiarrhythmic drugs and catheter ablation) has been proposed as a possible treatment of drug-induced AFL. The conversion from AFL to AF is less frequent and may be due to several mechanisms: a shortening of the length of the line of functional block, atrial ectopic beats or rapid atrial rhythm, focal activation from the pulmonary veins, alternans of atrial action potentials. Also, atypical right and left AFL can determine AF. Finally, atypical AFL may occur after AF ablation, and could be prevented by associated cavotricuspid isthmus ablation.     

Clinical importance of short–long–short sequences: Analysing the mode of onset of ventricular tachycardias and atrial fibrillation

Clinical importance of atrial and ventricular ectopic beats are investigated in some experimental and clinical trials. They are common and occur in a broad spectrum of the population. This includes patients without structural heart disease and those with any form of cardiac disease, independent of severity. Although we know something about the mechanisms and etiology of serious ventricular arrhythmias and atrial fibrillation, we don't know a lot about mode of onset of those arrhythmias. Can short-long-short sequences, related ectopic beats predict AF and ventricular tachycardias in some selected groups of patients? In this paper we will try to answer this important question.     

Changes in sinus RR interval patterns preceding ventricular ectopic beats: assessment with rate enhancement and dynamic heart rate trends.

Changes in heart rate preceding ventricular ectopic beats may be used to identify clinical subsets of patients. We evaluated RR interval patterns preceding ventricular ectopic beats with a rate enhancement method which estimates ventricular ectopic beat dependence on the sinus RR interval preceding the ventricular ectopic beat and the dynamic heart rate trend, which is based on the slope of the five RR intervals preceding the ventricular ectopic beat. Using these two methodologies in 176 patients with frequent ventricular ectopic beats we identified several unique subsets of patients: (1) bradycardia-enhanced patients were younger with a high proportion of males and longer, more variable coupling intervals; (2) tachycardia-enhanced patients exhibited sleep suppression of ventricular ectopic beats and had shorter, less variable coupling intervals; (3) patients with predominantly no change in RR preceding the ventricular ectopic beat were significantly older, with greater prevalence of cardiovascular disease and reduced sinus RR variability, indicating decreased autonomic nervous system activity. These two methods may serve as a basis for further investigations regarding the treatment and prognosis of ventricular ectopic beats.     

Surgical and catheter ablative techniques for treating supraventricular tachycardia.

Although antiarrhythmic drugs are commonly used in patients with supraventricular tachycardia, their use is limited due to inefficacy, side effects and patient compliance problems. Nonpharmacologic therapies used in the treatment of supraventricular tachycardia include: antitachycardia pacing, DC and radiofrequency catheter ablation and surgical therapy. Although certain pacing techniques can prevent the initiation of tachycardia, antitachycardia pacing is primarily used to terminate the supraventricular tachycardia once it has occurred. In patients with primary atrial tachycardias that are refractory to treatment, DC or radiofrequency catheter ablation can be used to modify or completely ablate the AV junction with resultant complete heart block. With DC AV junction ablation, 65% of patients will have resultant third degree AV block and 20% of patients will have modification of AV condition. Results with radiofrequency ablation have shown efficacy rates ranging from 56-9470 and can be used without the need for general anesthesia. Both forms of catheter ablation can be used to selectively alter the retrograde limb of an AV node reentrant circuit. Catheter ablation has been successful in ablating accessory pathways. DC catheter ablation has been predominantly used in posterior paraseptal pathways. More recently, radiofrequency catheter ablation of the ventricular insertion site of accessory pathways has demonstrated usefulness in selective laboratories. Surgical therapy for supraventricular tachycardia has been used for excision and/or ablation of an atrial ectopic focus, surgical ablation of the AV node in patients with refractory atrial tachyarrhythmias and microsurgery of the AV node in patients with AV node reentrant tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

分支起源室早的射频消融

目的探讨左室传导分支起源的室性早搏（Premature Ventricular Contractions,PVCs）的心电生理特点及导管射频消融（RadioFrequencyCatheterAblation,RFCA）方法。方法 14例排除器质性心脏病的左室分支起源的PVCs患者,3例行常规导管射频消融治疗,11例在三维电解剖标测（Carto）下射频消融治疗。结果14例患者均表现为＂反复心悸＂,PVCs均大于10000次/24h,7例伴有阵发性左室室性心动过速。6例左前分支起源患者的标准12导联心电图PVCs表现为心电轴右偏、右束支阻滞图形并左后分支阻滞（left posterior hemiblock,LPH）。8例左后分支起源患者的标准12导联心电图PVCs表现为心电轴左偏、右束支阻滞图形及左前分支阻滞（leftanteriorhemiblock,LAH）。在成功消融靶点（最早或提前激动点）附近均记录到浦肯野氏分支电位（Purkinje Potential,PP）,位于左室前外侧间隔、左室中间隔高位或左室后间隔中部,V波提前于体表心电图QRS波（33.0±10.1）ms;11例患者采用冷盐水灌注消融或普通Carto消融导管消融,3例常规7F双弯消融导管消融,放电即刻成功消融,无并发症。术后随访11±5个月,5例患者PVCs完全消失,9例患者24h动态心电图的PVCs小于1000次。结论起源于左室传导前、后分支起源的PVCs各有其临床特征,在消融导管标测到PVC最早或提前激动点并伴有PP处成功消融。     

Premature Ventricular Contraction–Induced Cardiomyopathy

Premature ventricular contractions are of common occurrence in routine clinical practice. Though generally perceived as of benign consequence in healthy people in the absence of heart disease, their presence can be a harbinger of fatal ventricular tachyarrhythmia in individuals with structural heart disease. With some of the latest insights into the treatment of ventricular tachyarrhythmia, especially with the advent of catheter ablation, there has been renewed interest in premature ventricular contractions, not only as a predictor of arrhythmia, but also for their potential etiological association with cardiomyopathy.     

Newer Methods for Ventricular Tachycardia Ablation and When to Use Them

Radiofrequency (RF) catheter ablation has long been an important therapy for ventricular tachycardia and frequent symptomatic premature ventricular beats and nonsustained arrhythmias when antiarrhythmic drugs fail to suppress the arrhythmias. It is increasingly used in preference to antiarrhythmic drugs, sparing the patient adverse effects of drugs. Success of ablation varies with the underlying heart disease and type of arrhythmia: very effective for patients without structural heart disease, less effective in structural heart disease. Failure occurs when a target for ablation cannot be identified or ablation lesions fail to reach and abolish the arrhythmia substrate that may be extensive, intramural, or subepicardial in location. Approaches to improving ablation lesion creation are modifications to RF ablation and emerging investigational techniques. Easily- implemented modifications to RF methods include manipulating the size and location of the cutaneous dispersive electrode, increasing duration of RF delivery, and use of lower-tonicity catheter irrigation (usually 0.45% saline). When catheters can be placed on either side of culprit substrate, RF can be delivered in a bipolar or simultaneous unipolar configuration that can be successful. Catheters with extendable and retractable irrigated needles for delivery of RF are under investigation in clinical trials. Cryoablation is potentially useful with specific situations in which maintaining contact is difficult. Transvascular ethanol ablation and stereotactic radioablation have both shown promise for arrhythmias that fail other ablation strategies. Although substantial clinical progress has been achieved, further improvement is clearly needed. With ability to increase ablation lesion size, continued careful evaluation of safety, which has been excellent for standard RF ablation, remains important.     

Morphologic features of right ventricular ectopic beats

A study of the morphologic features of right ventricular ectopic beats produced by stimulating the endocardium of the right ventricle with a nonpacing catheter tip, and a comparison of these features with the patterns of classic left bundle branch block, afforded the following clues: (1) a wide (> 0.04 second) r wave in lead V₁; (2) a QS or rS complex deeper in lead V₄ than in V₁; and (3) right axis deviation in the frontal plane occurring commonly in right ventricular ectopic beats and rarely in left bundle branch block.

Artificially paced right ventricular beats shared the first 2 characteristics (wide r wave in lead V₁ and deep QS or rS complex in lead V₄) with the ectopic beats produced at catheterizatton but, unlike them, displayed an invariable left axis deviation.

Application of these findings to the clinical tracing may be helpful in discriminating between right ventricular ectopic beats and aberration of the left bundle branch block type.     

Radiofrequency catheter ablation of ventricular tachycardias

Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.