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 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.     

Permanent junctional reciprocating tachycardia (Coumel type): an unusual location of a retrograde accessory pathway

Permanent junctional reentrant tachycardia (PJRT) is an uncommon form of tachycardia that is usually due to an atrioventricular reentry via a right posteroseptal accessory pathway with decremental properties. We describe a case of PJRT that showed evidence of two accessory pathways located both left and right. A 63-year-old woman was referred to our institution for radiofrequency (RF) ablation of a permanent form of regular narrow QRS tachycardia (T) (cycle length 520 ms) with long RP interval (380 ms); P wave was negative in inferior leads, negative in D1 and flat in aVL. During sinus rhythm, AH and HV intervals were 110 ms and 50 ms respectively. The atrioventricular anterograde conduction curve was continuous. A decremental retrograde conduction via a left posterior pathway until ventricular effective refractory period (210 ms) was evident. Tachycardia inducible with both atrial and ventricular programmed stimulation was almost incessant. During tachycardia, a premature ventricular depolarization delivered when His bundle was refractory was able to advance the next atriogram, and tachycardia could be interrupted by a ventricular depolarization without atrial capture. During right atrial mapping, an earliest atrial activation was found in the mid-septal position just above the coronary sinus ostium and RF application caused a transient interruption of T (3 minutes). Tachycardia resumed with basal characteristics, but no evidence of earlier right atrial activation was found during atrial mapping. Successful RF ablation was performed via retrograde aortic catheterization in the left posterior region. This case showed evidence of a left posterior pathway causing PJRT. However, the transient successful ablation in the right mid-septal region and the lack of evidence of right early atrial activation after RF application could account for the presence of an additional right accessory pathway or a strand of the same broad left pathway.     

温度监测控制在室性心动过速射频消融中的应用

在７例左室特发性室性心动过速病人成功射频消融中，使用温度监测控制，发现消融时电极一组织界面温度迅速升高，经过一定时间达到两种稳定的温度状态。即４８℃左右（４８．７±２．０℃）和７０℃左右（６６．０±４．８℃）．其输出功率分别为４８Ｗ和２２±１０．３（１５～３５）Ｗ（Ｐ＜０．００１）。无论输出功率多少，用７Ｆｒ可控大头导管电极，在放电开始后约４ｓ，局部温度可达４８℃，而达设定温度（７０℃）需１０ｓ左右，通过温度监测控制提示：放电５～１０ｓ消融不成功，应重新进行标测。此结论与临床观察相吻合。     

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.     

Catheter Ablation of the Left Ventricular Outflow Tract Tachycardia from the Left Atrium

RF ablation of idiopathic left ventricular outflow tract ventricular tachycardia (LOT-VT) may imply in significant risk of damaging the proximal left main if RF pulses are being delivered from the left sinus of Valsalva or from inside an epicardial coronary vein. This report describes a new approach to control LOT-VT by means of RF catheter ablation.     

Ablation of idiopathic ventricular tachycardia by bipolar radiofrequency current application between the left aortic sinus and the left ventricle.

BACKGROUND: Failure to ablate idiopathic ventricular outflow tract tachycardia by radiofrequency current is not uncommon and suggests that non-standard approaches may be required to map and suppress idiopathic ventricular tachyarrhythmias in some patients. METHODS AND RESULTS: Left and right ventricular activation and pace mapping proved inadequate for radiofrequency application in a patient with idiopathic ventricular outflow tract tachycardia. Presystolic activity was recorded at the left aortic sinus of Valsalva, and the QRS complex recorded at this location during pacing showed few differences compared with that recorded during tachycardia. Radiofrequency current application at this site transiently suppressed the tachycardia. Following new mapping of the left ventricle outflow tract, radiofrequency application just below the aortic valve in close proximity to the previous aortic application site transiently abolished the arrhythmia. Finally, bipolar radiofrequency application between the distal electrode of the aortic catheter and the distal electrode of a second catheter placed in the left ventricular subaortic area permanently suppressed the tachycardia. CONCLUSION: Bipolar radiofrequency application between the aortic sinus of Valsalva and the left ventricle could be an alternative approach in occasional patients with idiopathic ventricular outflow tract tachycardia resistant to conventional left ventricular and aortic root unipolar radiofrequency application.     

射频消融左后分支治疗维拉帕米敏感性特发性室性心动过速

目的报道消融左后分支治疗左室特发性室性心动过速(简称室速)。方法对57例维拉帕米敏感性左室特发性室速患者进行电生理检查及射频消融,以窦性心律时产生左后分支阻滞和/或室速不再被诱发作为消融成功终点。结果57例中41例室速诱发条件稳定(71.9%),9例诱发条件不稳定(15.8%),7例不能被诱发(12.3%),所有患者均达消融成功终点。术后全部患者体表心电图Ⅰ导联出现R波降低,S波加深,呈rS形态或RS形态,Ⅱ、Ⅲ、aVF导联出现小q波,或在原有q波基础上加深,R波振幅明显增高,呈qR形态,额面电轴度数显著增加(54.06°±38.24°vs 90.55°±7.88°,P<0.001)。27例出现完全性左后分支阻滞改变(47.4%),30例为不完全性左后分支阻滞(52.6%)。1例1年后室速再发,左后分支阻滞消失,重复消融直至再次出现左后分支阻滞,术后室速未有再发。结论射频消融产生左后分支阻滞可作为左室特发性室速的消融成功终点,尤其适用于不易被常规电生理检查诱发的患者。     

Radiofrequency ablation of idiopathic left ventricular tachycardia at the site of earliest activation as determined by noncontact mapping

INTRODUCTION: The most effective method for guiding radiofrequency (RF) ablation of idiopathic left ventricular tachycardia (ILVT) has yet to be determined. We investigated the use of noncontact mapping in five patients with this condition. METHODS AND RESULTS: The multielectrode array was positioned in the left ventricular apex via the retrograde approach. Isopotential color maps of ILVT were examined to determine the site of earliest endocardial activation. The ablation catheter was steered to the target site using the locator signal. Pace mapping was performed and contact electrograms examined for diastolic potentials. RF energy was applied to the target site. Sustained ventricular tachycardia was induced in 2 patients and nonsustained ventricular tachycardia in 3. The site of earliest activation was at the apical septum in 3, the inferior apex in 1, and the base of the inferior wall in 1. Mean timing was 21 +/- 10 msec before onset of the surface QRS. Diastolic activity was visualized with noncontact mapping at the base of the septum in 1 patient. A Purkinje potential was seen at the ablation site in only 1 patient. No diastolic activity was seen in the remaining 3 patients. Tachycardia was successfully terminated in all 5 patients with a median of four RF applications. No patient suffered a recurrence after 9.6 +/- 4.7 months of follow-up. CONCLUSION: By identifying the precise site of earliest activation during ILVT, noncontact mapping has been shown to be an effective and safe method for guiding RF ablation.     

Radiofrequency catheter ablation of coexistent atrioventricular reciprocating tachycardia and left ventricular tachycardia originating in the left anterior fascicle

Coexistence of supraventricular tachycardia and ventricular tachycardia is rare. A patient with no structural heart disease and wide QRS complex tachycardia with a right bundle block configuration and right-axis deviation underwent electrophysiological examination. A concealed left atrioventricular pathway (AP) was found, and atrioventricular reciprocating tachycardia (AVRT) and left ventricular tachycardia (VT) originating in or close to the anterior fascicle of the left ventricle were both induced. Radiofrequency (RF) catheter ablation of the concealed left AP was successfully performed. Ten months later, VT recurred and was successfully ablated using a local Purkinje potential as a guide. Coexistent AVRT and idiopathic VT originating from within or near the left anterior fascicle were successfully ablated.     

Epicardial and endocardial mapping determine most successful site of ablation for ventricular tachyarrhythmias originating from left ventricular summit

A 34-year-old woman presented with idiopathic premature ventricular complex (PVC) and ventricular tachycardia (VT) originating from the area called the left ventricular summit. Radiofrequency (RF) application both through the coronary sinus and to the epicardial surface transiently suppressed the VT/PVC. Radiofrequency with sufficient energy was only applicable from the endocardial site, and the VT/PVC was successfully eliminated.     

Electrophysiologic characteristics and radiofrequency ablation of concealed nodofascicular and left anterograde atriofascicular pathways

INTRODUCTION: True nodoventricular or nodofascicular pathways and left-sided anterograde decremental accessory pathways (APs) are considered rare findings. METHODS AND RESULTS: Two unusual patients with paroxysmal supraventricular tachycardia were referred for radiofrequency (RF) ablation. Both patients had evidence of dual AV nodal conduction. In case 1, programmed atrial and ventricular stimulation induced regular tachycardia with a narrow QRS complex or episodes of right and left bundle branch block not altering the tachycardia cycle length and long concentric ventriculoatrial (VA) conduction. Ventricular extrastimuli elicited during His-bundle refractoriness resulted in tachycardia termination. During the tachycardia, both the ventricles and the distal right bundle were not part of the reentrant circuit. These findings were consistent with a concealed nodofascicular pathway. RF ablation in the right atrial mid-septal region with the earliest atrial activation preceded by a possible AP potential resulted in tachycardia termination and elimination of VA conduction. In case 2, antidromic reciprocating tachycardia of a right bundle branch block pattern was considered to involve an anterograde left posteroseptal atriofascicular pathway. For this pathway, decremental conduction properties as typically observed for right atriofascicular pathways could be demonstrated. During atrial stimulation and tachycardia, a discrete AP potential was recorded at the atrial and ventricular insertion sites and along the AP. Mechanical conduction block of the AP was reproducibly induced at the annular level and at the distal insertion site. Successful RF ablation was performed at the mitral annulus. CONCLUSION: This report describes two unusual cases consistent with concealed nodofascicular and left anterograde atriofascicular pathways, which were ablated successfully without impairing normal AV conduction system.     

Radiofrequency Catheter Ablation of Idiopathic Ventricular Tachycardia Originating in the Anterior Fascicle of the Left Bundle Branch

Ablation of an Anterior Fascicular Idiopathic VT. Introduction : Idiopathic ventricular tachycardia (VT) originating in or close to the anterior fascicle of the left bundle is rare. A patient with no structural heart disease and VT with a right bundle branch block configuration and right-axis deviation underwent an electrophysiologic examination.
Methods and Results : Both endocardial activation mapping during VT and pacemapping were performed via a transseptal approach to localize the site of origin of the VT. Endocardial recordings of the His bundle and the posterior and anterior fascicles of the left bundle branch revealed an origin of the VT in or close to the anterior fascicle. The Purkinje potential at that site preceded the QRS complex by 20 msec, with pacemapping showing an optimal match between the paced rhythm and the clinical VT. RF energy delivered at this site terminated the VT. A left anterior nemiblock appeared after RF ablation. Ten months later, the patient is free from recurrences of VT.
Conclusions : Idiopathic VT originating in or close to the anterior fascicle was cured by RF ablation. A Purkinje potential preceding the QRS during tachycardia and an optimal pacemap were used to guide RF ablation.     

Radiofrequency catheter ablation of postinfarction ventricular tachycardia from the proximal coronary sinus

Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57-year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible.     

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.     

Chemical ablation of ventricular tachycardia in the dog

Sustained ventricular tachycardia was induced in dogs following occlusion-reperfusion of the left anterior descending coronary artery. While dogs were supported by cardiopulmonary bypass, the left ventricle was opened and the endocardium was mapped during electrically induced ventricular tachycardia to determine the earliest site of ventricular activation. Phenol (carbolic acid) application at that site necrosed myocardium to a depth of 1 to 3 mm and prevented electrical reinduction of ventricular tachycardia in 9 of 15 dogs. These data suggest that chemical ablation may be used as an alternate means to destroy areas of myocardium involved in the genesis or maintenance of ventricular tachycardia, particularly if these areas cannot be resected surgically because of their size or location.     

Analysis of Posterior Mitral Annular Activation During Entrainment and Catheter Ablation of Mitral Isthmus Ventricular Tachycardia Using a Coronary Sinus Catheter

A detailed analysis of the ventricular activation along the posterior aspect of the mitral annulus was made using a multipolar catheter positioned in the coronary sinus in a patient with mitral isthmus ventricular tachycardia (VT) associated with a remote inferior myocardial infarction and prior cryosurgical ablation for the elimination of a different preexisting VT. A change in the timing and sequence of the ventricular activation along the isthmus could be observed during induction of the VT and entrainment pacing. A radiofrequency (RF) current application directed at the posterolateral region of the isthmus successfully eliminated this tachycardia. During the RF delivery, complete conduction block was confirmed by a sudden change in the activation sequence during sinus rhythm.     

Adenosine can improve the intra-atrial conduction block along the mitral annulus during accessory pathway ablation

A 10-year-old boy with a supraventricular tachycardia was referredfor catheter ablation. An electrophysiologic study revealeda left lateral concealed accessory pathway (AP). A few radiofrequency(RF) applications targeting the AP resulted in an inadvertentintra-atrial conduction block at the mitral isthmus withoutany damage to the AP. Adenosine was then administered duringleft ventricular pacing. Soon after that, the conduction atthe mitral isthmus recovered partially, and that change disappearedsoon. Those findings suggested that the administration of adenosinemay transiently recover the conduction at the mitral isthmusdamaged by RF ablation.     

Effects of Radiofrequency Catheter Ablation on Patients with Permanent Pacemakers

The objective of this study was to assess the effects ofradiofrequency energy application on implanted pacemaker functions.Radiofrequency (RF) catheter ablation may cause pacemaker dysfunction dueto electromagnetic interferences. The effects of RF on pacemaker behaviorwere studied in a series of 38 pacemakers, implanted 18 ± 26 monthsprior to a RF procedure using either a right ventricular approach (AV nodeablation, n = 35) or a left ventricular approach (left concealedaccessory pathway ablation, n = 1; VT ablation, n = 2). The38 patients (mean age 65 ± 9 years) included 20 men and 18 women.Before energy applications, the 23 different pacemaker models wereprogrammed to the VVI mode at the lowest available rate. The continuoussurface ECG was recorded throughout the procedure. Thorough testing of thedevices was performed before and after each RF delivery. Unusual pacemakerresponses occurred in 20 of the 38 cases studied (53%). The impactof RF delivery was unpredictable, and variable dysfunctions were observedat different times for a given patient or could vary for a given model.Unusual pacemaker responses included pacemaker inhibition (n = 8), untoggled backup mode (n = 3), electromagnetic interference noisemode (n = 3), temporary RF-induced pacemaker tachycardia (n =2), erratic behavior (n = 1), oversensing of RF onset and offset (n= 8), and transient loss of ventricular capture, (n = 1).Postablation, most devices automatically toggled back to fullfunctionality. The three devices in the untoggled backup mode had to bereprogrammed to obtain normal operations. At the end of the procedure,pacing thresholds remained unchanged in all but one patient, in whom theincrease in ventricular threshold was due to a nicked lead. In conclusion,implanted pacemakers frequently exhibit transient, unpredictable responsesto RF energy application. Although all pacemaker functions were restored postablation, some devices had to be reset manually. The anomalies observedduring the RF application argue for the simultaneous use of an externalpacemaker in pacing-dependent patients.     

Dual Morphology of Idiopathic Ventricular Tachycardia

INTRODUCTION: Idiopathic ventricular tachycardia (VT) typically has a single morphology originating either in the right ventricular outflow tract (RVOT) or near the posterior fascicle of the left ventricle (LV) in most instances. We present our observations in six patients with idiopathic VT in whom two morphologies were present. METHODS AND RESULTS: Of 55 patients with idiopathic VT who underwent radiofrequency (RF) ablation, 44 had LV "fascicular" tachycardia, whereas 11 had RVOT tachycardia. During RF energy delivery, there was a change in VT morphology in two patients with idiopathic LV tachycardia. This second morphology was not ablated initially, recurred at follow-up, and was reablated successfully. In two additional patients with idiopathic LV tachycardia, a second VT was inducible after ablation of the "clinical" VT. This second morphology recurred at follow-up and was ablated successfully in one patient. The site where the second VT was ablated in all the three patients was remote from that of the first VT. In two patients with RVOT tachycardia, a second VT, originating from a different area of the RVOT, was induced after RF ablation of the "clinical" VT. This second VT recurred at follow-up and was reablated successfully in one patient. CONCLUSION: Idiopathic VT is a more heterogenous entity than hitherto believed. A second VT was seen in 11% of patients during or after RF ablation of the "clinical" VT. The appearance of a second VT suggests either a different exit site of the same circuit or another site of origin.