Ventricular tachycardia ablation: indications and techniques

Over the last decades indications have broadened and techniques have been developed resulting in an increasing use of catheter ablation for different types of ventricular tachycardia (VT). Due to the high ablation success for non scar-related ventricular arrhythmia (VA) catheter ablation has become a first line therapy for symptomatic idiopathic VA or VA presumed to cause ventricular dysfunction. For the ablation of scar-related VTs individual patient factors and operator experience play an important role in risk-benefit considerations. However, the development of substrate based techniques, irrigated tip catheter ablation and the introduction of a percutaneous epicardial approach in selected patients has greatly enhanced the treatment of VTs in patients with structural heart disease. Understanding of the VT substrate in different diseases and individual patients is important for mapping and ablation. Advances in substrate imaging technologies and their integration during ablation procedures may provide more insights into the substrates and may guide VT ablation in the future. The distinction between scar-related and non scar-related VT is relevant because it may affect treatment and prognosis. Distinction between these entities may be facilitated by identification of the VT substrate during catheter mapping. Failure of catheter ablation is often due to the anatomical localization of the arrhythmic source or reentry circuit. However, evolving new catheter techniques and energy sources may overcome these limitations.     

Ventricular tachycardia as a complication of atrial flutter ablation

A 61-year-old woman with dilated cardiomyopathy, who previously underwent successful radiofrequency catheter ablation for atrial flutter, developed monomorphic ventricular tachycardia (VT). The site of VT origin was the inferobasal right ventricle adjacent to the previous atrial isthmus ablation area. The most likely mechanism for the VT was scar-related reentry, the scar being the result of previous radiofrequency lesions in the atrial isthmus. The VT was successfully ablated.     

Ventricular fibrillation secondary to radiofrequency application in ventricular tachycardia ablation

Radiofrequency catheter ablation has become a first line therapy for several types of tachycardias because of its high efficacy and low complication rate. The development of proarrhythmic complications due to a direct effect of radiofrequency is very unusual. We describe a patient with previous myocardial infarction and well tolerated sustained monomorphic ventricular tachycardia who underwent catheter ablation of the tachycardia substrate. During two of the radiofrequency applications, ventricular fibrillation developed and external defibrillation was required.     

Ventricular tachycardia in cardiac sarcoidosis controlled by radiofrequency catheter ablation

We report a case of a 78-year-old woman with cardiac sarcoidosis with a history of syncope and palpitation. Further assessment with echocardiography, gadolinium-enhanced cardiovascular magnetic resonance (CMR) and histology led to a diagnosis of cardiac sarcoidosis. As the patient suffered from ventricular tachycardia (VT) despite active corticosteroid therapy, an implantable cardioverter-defibrillator (ICD) was positioned. She was also administered a beta blocker, but an electrical storm appeared every several days requiring ICD therapy. The drug-refractory VT was finally controlled with a catheter ablation session, during which we could detect the VT focus in the right ventricular outflow tract next to the aneurysm by using an electroanatomic mapping system (CARTO). Referring to echocardiographic and CMR images proved very useful in detecting the aneurysm using the CARTO system.     

Ventricular tachycardia: an unusual pacemaker-mediated tachycardia.

A 74 year old man had recurrent ventricular tachycardia, which was well controlled with amiodarone, and complete heart block for which a VVI permanent pacing system had previously been implanted. After an elective increase in the programmed pacemaker rate from 70 to 82 beats/min, there was recurrence of frequent episodes of ventricular tachycardia. Each episode of tachycardia was initiated by a fusion beat consisting of a ventricular extrasystole and a paced beat. When the pacemaker rate was reprogrammed to 70 beats/min the episodes of tachycardia ceased abruptly. It is proposed that the fusion of a ventricular extrasystole with a pacemaker beat may have induced ventricular tachycardia, even though neither of these beats occurring separately was sufficient to cause this.     

Ventricular tachycardia

The major differential diagnosis for VT is supraventricular tachycardia with a wide QRS complex due to aberrant conduction. Although VT may be slightly irregular, gross irregularities, such as those typically seen in atrial fibrillation, are uncommon during VT; such marked irregularities suggest atrial fibrillation. The QRS configuration is helpful in differentiating supraventricular tachycardia from VT. Supraventricular tachycardia with aberration generally produces QRS complexes that are less than 0.14 second in duration, whereas wider complexes are common in VT. The presence of an antiarrhythmic drug may, however, render this criterion unhelpful.     

Ventricular tachycardia ablation in patients with coronary heart disease: beyond the reentry circuit.

INTRODUCTION: Patients with coronary heart disease and left ventricular dysfunction are at increased risk for the development of ventricular tachycardia (VT) related to areas of myocardial fibrosis. Although the mechanism and the circuit of this arrhythmia are well understood, little is known about the triggers that precipitate VT episodes. Purkinje fiber potentials may be responsible for idiopathic VT, and recent studies have related them to polymorphic VT and ventricular fibrillation. METHODS: Between January 2002 and December 2003, we performed ablation in 10 patients with coronary heart disease, left ventricular systolic dysfunction and VT refractory to pharmacological therapy. All patients had implantable cardioverter-defibrillators. Electroanatomical activation and voltage mapping (CARTO) and electrophysiological criteria (premature activation during VT, pace mapping, and presence of diastolic potentials) were used to define scar regions, slow conduction areas and the reentry circuit isthmuses. RESULTS: Spike potentials were recorded in the scars of three patients. These potentials were almost fused with the ventricular electrogram during sinus rhythm, and were more premature during VT, probably reflecting local activation of Purkinje fibers. During ablation, we were able to dissociate the spike from the ventricular electrogram, thus terminating the VT. In the cases with conduction recovery, ventricular; ectopic beats recurred, preceded by a spike and degenerating into short runs of VT. The ablation strategy was not modified since persistence of the VT required the isthmus. CONCLUSION: The results suggest that residual Purkinje fibers may be present in scar regions and that the activity of these fibers may trigger VT in pre-established circuits.     

Ventricular tachycardia in Chagas' disease.

This study examined the usefulness of the electrophysiologic approach for selecting antiarrhythmic drug therapy to improve survival in patients with ventricular tachycardia (VT) and Chagas' disease. A total of 71 consecutive chagasic patients undergoing treatment and evaluation of VT were analyzed. Programmed electrical stimulation (PES) was performed in 45 patients, sustained VT was induced in 18 of these 45 (40%); nonsustained VT was induced in 17 (38%), and in 10 patients (22%) VT was not induced at all. An average of 3 drugs per patient were tested, including mexiletine, flecainide and propafenone. At least 1 effective drug preventing VT induction was identified in 13 of 18 patients with induced sustained VT, whose outcome resulted in 2 nonsudden but cardiac deaths (15%). Eight patients received no drug therapy because the induced arrhythmia was asymptomatic nonsustained VT; none of these died. The remaining 24 patients from the PES group were empirically treated with amiodarone; 7 died (4 suddenly) during follow-up (29%). A group of 26 patients (non-PES group) did not undergo electrophysiologic evaluation. In these patients, the therapy chosen was amiodarone alone or associated with mexiletine, and the incidence of death was 7 of 26 patients (27%), 3 suddenly (p less than 0.05 at 10-year survival and p = not significant at 5-year survival). It is concluded that the electrophysiologic approach improves survival in this study population, but only 29% were eligible for guided therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ventricular unipolar potential in radiofrequency catheter ablation of idiopathic non-reentrant ventricular outflow tachycardia

We conducted this study to verify the efficacy of ventricular unipolar potential (V-uni) for ablation of idiopathic non-reentrant ventricular tachycardia (idio-VT). The morphology of V-uni at the successful and unsuccessful sites was analyzed in 27 patients with idio-VT [20 with right ventricular outflow tachycardia (RVOVT) and 7 with left ventricular outflow tachycardia (LVOVT)]. The usefulness of V-uni was compared with a pacemapping method and the V-QRS interval. The incidence of QS-pattern V-uni at the successful and best unsuccessful sites were 100 versus 25% (P = 0.000005) in RVOVT and 86 versus 29% (P = 0.10) in LVOVT. The pacemapping scores at the successful and best unsuccessful sites were 11.5/12 versus 11.2/12; NS in RVOVT, and 11.2/12 versus 11.1/12; NS in LVOVT. The mean V-QRS interval at the successful and the best unsuccessful sites were 22.5 +/- 3.8 versus 21.6 +/- 3.4 msec; NS in RVOVT, 15.1 +/- 3.2 versus 12.5 +/- 3.3 msec; NS in LVOVT. The sensitivity (sen) and specificity (spe) of QS-pattern V-uni to determine the optimum target sites were 1.0 and 0.89 in RVOVT and 0.86 and 0.83 in LVOVT, respectively. In the ablation of idio-VT, QS-pattern V-uni is simply and visually identifiable, is very useful, and should be given a high priority when determining the optimum target site.     

Ventricular tachycardia ablation guided by LocaLisa system in patients with structural heart disease

INTRODUCTION: The ablation of ventricular tachycardia is limited by a number of factors that reduce the effectiveness of this intervention in patients with structural heart disease compared to other types of arrhythmia. Recent years have seen the development of several nonfluoroscopic navigation techniques that facilitate the mapping of complex arrhythmogenic substrates. One such technique, the LocaLisa system, has not previously been tested for the ablation of ventricular tachycardia. PATIENTS AND METHOD: A total of 32 patients with structural heart disease were treated at our center with ablation for sustained ventricular tachycardia. In 10 patients the LocaLisa system was used to visualize the catheters during the procedure. We compared the results in the LocaLisa group with those in a control group of 22 patients treated with conventional fluoroscopy-guided ablation. RESULTS: The success rate of ablation was 75% (9/12 procedures) in the LocaLisa group and 68% (17/25 procedures) in the control group (P=NS). In the LocaLisa group, mean total duration of the procedure (243 +/- 84), duration of ablation (86 +/- 56) and fluoroscopy time (46 +/- 19) did not differ significantly from those in the control group (244 +/- 72 min, 79 +/- 58 min, and 43 +/- 27 min, respectively). In the LocaLisa group the trend toward greater hemodynamic intolerance in ventricular tachycardia approached significance (42% in the LocaLisa group vs 24% in the control group, P=.05) and the number of mapping procedures performed during sinus rhythm was significantly higher in the former (33% in the LocaLisa group vs 4% in the control group, P=.03). With the LocaLisa system it was possible to locate and reposition the ablation catheter accurately at the target endocardial sites, as confirmed by electrographic recordings and fluoroscopic verification. CONCLUSIONS: The LocaLisa system helps to delineate the reentry circuit and facilitates accurate catheter repositioning in patients with structural heart disease and ventricular tachycardia.     

Ventricular tachycardia induced by clonidine withdrawal.

Ventricular tachycardia developed after the abrupt withdrawal of clonidine in a patient with atrial septal defect of the ostium secundum type, renal insufficiency, and hypertension. Ventricular tachycardia was completely suppressed by intravenous phentolamine, which contrasted with the limited effectiveness of intravenous lignocaine and procainamide. Sublingual glyceryl trinitrate or inhaled amyl nitrate reduced the blood pressure to a level similar to that after phentolamine but had no effect on the ventricular tachycardia. Ventricular tachycardia was probably produced by humoral or neural stimulation, or both, of upregulated myocardial alpha adrenoceptors.     

Ventricular tachycardia catheter ablation in arrhythmogenic right ventricular dysplasia: A 16-year experience

Arrhythmogenic right ventricular dysplasia (ARVD) is a structural heart disease affecting young adults that leads to cardiac rhythm disorders including supraventricular and mostly ventricular arrhythmias. Sudden death may be the first presentation of the disease. Ablation techniques have been used for the treatment of ventricular tachycardia in cases resistant to drug therapy. Radiofrequency is appropriate as a first approach for ventricular tachycardia ablation in ARVD; however, its effectiveness is less than 40% at the first session. Fulguration is effective for ventricular tachycardia ablation and should be used in the same session after ineffective radiofrequency ablation. However, fulguration requires expertise, general anesthesia, and more than one session in half of all patients. Radiofrequency and fulguration plus other common forms of treatment including pacemakers and automatic implantable cardioverter defibrillators provides a clinical success rate of 81% to 93% in a series of 50 consecutive patients studied during 16 years. Earlier poor reputation of fulguration was the result of poorly understood technical problems concerning the physics and biophysics of the procedure under control with presently available methods. This in-depth study of a large population over a long time period demonstrates that fulguration should be rehabilitated.