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Introduction and Objectives: The importance of the clinical presentation in the frequency and type of recurrences of ventricular arrhythmias in patients that received an automatic implantable defibrillator is not well known. The purpose of this study was to analyze the frequency and type of recurrences in patients with an old myocardial infarction that received an automatic implantable defibrillator with electrogram recording., Methods and Results: We analyzed 100 patients classified in 3 groups according to their clinical presentation: Sustained Monomorphic Ventricular Tachycardia (VT Group n = 65), Cardiac Arrest (CA Group = 19), and Syncope (Syncope Group n = 16). There were no significant differences in the clinical variables among the different groups, nor in the inducibility of arrhythmia at the electrophysiologic study. In a follow-up 27 +/- 14 months, 54% of patients presented at last one episode of sustained ventricular arrhythmia. All recurrences except one were as sustained monomorphic ventricular tachycardia (776 episodes). 81% of episodes of sustained monomorphic ventricular tachycardia (630) were treated with antitachycardia pacing with an effectiveness of 89%. There were no differences in the probability of arrhythmic recurrence among groups but death probability was higher in the ventricular fibrillation group at 36 follow-up months (38% vs 7% and 12% in the sustained monomorphic ventricular tachycardia and syncope groups respectively, p = 0.0113)., Conclusions: In the patients with an old myocardial infarction and malignant ventricular arrhythmias, most of recurrences are due to sustained monomorphic ventricular tachycardia independently of the clinical presentation. The antitachycardia pacing is not only effective in patients with documented sustained monomorphic ventricular tachycardia but also in those that are presented as cardiac arrest or syncope.

Introduction and Objectives: Radiofrequency ablation of left sided accessory pathways requires multiple pulses in some patients due to different factors such as inadequate mapping, inappropriate tissue electrode contact and particular anatomic factors. However these characteristics have not been specifically analyzed., Methods: We have studied a prospective ablative series of 65 consecutive patients with left-sided pathways submitted to radiofrequency ablation by a simplified technique. In every application point, we analyzed the electrogram features, application point, impedance, potency and temperature., Results: 52 patients (80%) required less than 5 radiofrequency pulses (group A) and 13 (20%) required > or = than 5 pulses (group B). The presence of a suggestive potential accessory pathway in local electrogram was similar in both groups and there were no differences in the local A-V or V-A intervals. However, in patients with pre-excitation the Delta-V interval was shorter in group A than in group B (8 ms vs 15 ms; p < 0.001). Furthermore, the impedance observed from the ablation point in group A was lower (108 +/- 12 vs 121 +/- 22 ohms; p < 0.001), and the maximum watts required to reach the predetermined temperature was higher in group A (42 +/- 16 vs 31 +/- 18 watts; p < 0.001). Final success of the procedure was 100%., Conclusions: Patients requiring more than 5 radiofrequency pulses had electrograms and tissue contact equal or better than those requiring less than 5 pulses. This suggests that difficulties encountered in some procedures can be due to anatomical factors rather than inaccurate mapping or insufficient tissue contact.

Multiple accessory pathways in patients with the Wolff-Parkinson-White syndrome are infrequent and are associated with a higher risk of ventricular fibrillation. We present an exceptional case of a patient with four accessory pathways with anterograde conduction and a fasciculo-ventricular fiber in whom we performed a radiofrequency ablation. A 20 year old healthy male patient was seen at the emergency room after suffering syncope. The electrocardiogram showed atrial fibrillation with wide QRS complex suggestive of preexcitation. The electrophysiologic study demonstrated the presence of four atrio-ventricular accessory pathways with antegrade conduction (left lateral, right posteroseptal, right midseptal and right posterolateral). After ablation of the fourth accessory pathway, the electrocardiogram showed a persistent delta wave with a short HV interval. Atrial stimulation demonstrated decremental conduction, progressive lengthening of the AH interval and no modification in the HV interval nor in the preexcitation pattern, suggestive of the presence of a fasciculo-ventricular fiber. This exceptional case report is demonstrative of the complexity of the Wolff-Parkinson-White syndrome, and the feasibility and efficacy of radiofrequency catheter ablation in a single procedure.

Objectives: This study evaluates the hypothesis that in patients with syncope of unknown origin and heart anomalies, inducible ventricular arrhythmias are specific arrhythmias and therefore should be treated as such., Background: Although syncope is a frequent clinical entity, the evaluation and treatment of patients with syncope without a clear etiology still remains undefined. Many patients with syncope of undetermined origin undergo invasive electrophysiologic evaluation. Abnormalities of the sinus node, prolongation of conduction times or inducible arrhythmias found during these evaluations are usually assumed to be the cause of syncope, and are consequently treated. However, whether tachyarrhythmias are truly the cause of syncope, and whether treatment of these tachyarrhythmias can prevent recurrent syncope and arrhythmic death, is unknown., Patients and Methods: An electrophysiological study was performed on 160 patients with structural heart disease and syncope of unknown origin. In 23 out of the 160 patients (16%), programmed electrical stimulation induced sustained ventricular arrhythmias. In 18 out of the 23 patients an automatic defibrillator was implanted and they form the study group., Results: In these 18 patients, programmed ventricular stimulation induced sustained monomorphic ventricular tachycardia in 12, sustained polymorphic ventricular tachycardia in 2 and ventricular fibrillation in 4. During a mean follow-up of 14 months, 9 patients received 81 appropriate therapies from the device (53 because of ventricular tachycardia and 23 because of ventricular fibrillation). The probability of appropriate therapy was 100% at 1 year follow-up. There were no episodes of sudden death and 1 patient died of congestive heart failure., Conclusions: In patients with syncope of undetermined origin, heart disease and inducible ventricular tachyarrhythmias treated with a implantable cardioverter defibrillator, there is a high incidence of appropriate therapies. Our results support the practice of using implantable cardioverter defibrillators in patients with syncope of unknown origin, heart disease and inducible ventricular arrhythmias.

Introduction: Radiofrequency ablation of the atrioventricular conduction system has become an established therapy for patients with drug-refractory atrial fibrillation. We observed 14 patients with hemodynamic deterioration related to worsening of mitral regurgitation after the procedure., Patients and Methods: We retrospectively evaluated 256 consecutive patients with drug-refractory atrial fibrillation referred for radiofrequency ablation of the AV node and implantation of a pacemaker. Because we found hemodynamic deterioration related to worsening mitral regurgitation, we compared the clinical history, electrophysiologic and echocardiographic data from the patients with hemodynamic deterioration and worsening mitral regurgitation (group A) with those without hemodynamic deterioration (group B)., Results: Fourteen out of 256 patients (group A) undergoing ablation of the atrioventricular conduction system deteriorated with acute pulmonary edema (3 patients) or congestive heart failure (11 patients) at a mean of 6 weeks after the ablation procedure. Four of these patients were referred for mitral valve surgery. The length of the procedure and the number of applications during ablation were similar in both groups. Compared with group B patients, group A patients had significantly higher left ventricular end-diastolic diameters (64 +/- 6 mm vs 56 +/- 9 mm; p < 0.05) at baseline despite similar left ventricular end-systolic diameters, fractional shortening and grade of mitral regurgitation (1.15 +/- 1.05 vs 1.11 +/- 0.97). Moreover, whereas no change was observed in left ventricular end-diastolic diameter, left ventricular end-systolic diameter, fractional shortening and grade of mitral regurgitation in group B patients after ablation, group A patients experienced a significant increase in left ventricular end-diastolic diameter (64 +/- 6 mm vs 72 +/- 9 mm; p < 0.01) and grade of mitral regurgitation (1.15 +/- 1.05 vs 2.90 +/- 1.15; p < 0.01). In patients operated on no ablation related structural damage to the mitral valve apparatus could be detected. The worsening of the mitral regurgitation was related to dilation of the mitral valve annulus., Conclusions: Hemodynamic deterioration together with progression of mitral regurgitation is a potential complication of ablation of the atrioventricular conduction system.

Objectives: This study sought to determine the long-term follow-up, safety and efficacy of radiofrequency catheter ablation in patients with the permanent form of junctional reciprocating tachycardia. We assessed the reversibility of tachycardia-related left ventricular dysfunction and we detailed the location and electrophysiologic characteristics of these atrioventricular decremental pathways., Background: Permanent junctional reciprocating tachycardia is an infrequent form on reciprocating tachycardia, commonly incessant and usually drug-refractory. The electrocardiographic hallmarks include an RP interval > PR with inverted P waves in leads II, III, aVF and V3-V6. During tachycardia, retrograde ventriculo-atrial conduction occurs over an accessory pathway with decremental conduction properties, located predominantly in the posteroseptal zone. It is known that long lasting and incessant tachycardia may result in tachycardia-related severe ventricular dysfunction, the so called tachycardiomyopathy., Patients and Methods: We included 24 patients (9 males, 15 females; mean age 42 +/- 22 years) with the diagnosis of permanent junctional reciprocating tachycardia at electrophysiologic study. Six patients had tachycardia-related left ventricular dysfunction. Radiofrequency energy was delivered at the site of earliest retrograde atrial activation during reciprocating tachycardia (n = 22) or ventricular pacing (n = 2). All patients were followed at the outpatient clinic and serial echocardiograms were performed in those who presented depressed left ventricular function., Results: Radiofrequency catheter ablation was performed in 24 decremental accessory pathways. Earliest retrograde atrial activation was right posteroseptal in 22 patients (92%), right midseptal in 1 (4%) and right posterolateral in 1 (4%). Twenty-three accessory pathways were successfully ablated with a mean of 5 +/- 3 (median, 4) radiofrequency applications of a mean duration of 48 +/- 13 s. Only the midseptal accessory pathway could not be ablated. After a mean follow-up of 21 +/- 16 months (median, 15; range 2 to 64) 22 patients remain asymptomatic. There were recurrences in 4 patients after the initial successful ablation (three during the first month and one during the second month after the procedure), two were ablated in a second ablation procedure, one patient required a third procedure and one required a fourth. All patients with left ventricular dysfunction experienced an improvement after ablation. Mean preablation left ventricular ejection fraction in patients with tachycardiomyopathy was 28 +/- 6% (median, 27) and raised to 51 +/- 16% (median, 47) after ablation (p < 0.02)., Conclusions: Our study supports the concept that radiofrequency catheter ablation is a safe and useful treatment for patients with permanent junctional reciprocating tachycardia. Radiofrequency current should be the treatment of choice in these patients because this arrhythmia is usually drug-refractory. The majority of accessory pathways with decremental conduction properties are localized in the posteroseptal zone. Cessation of the arrhythmia after successful ablation results in recovery of left ventricular dysfunction.