André d'Avila

Radiofrequency Catheter Ablation of Ventricular Tachycardia Guided by Nonsurgical Epicardial Mapping in Chronic Chagasic Heart Disease

We report a case of a 63‐year‐old women with Chagasdisease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.

Effects of radiofrequency pulses delivered in the vicinity of the coronary arteries : Implications for nonsurgical transthoracic epicardial catheter ablation to treat ventricular tachycardia

DAVILA, A., et al.: Effects of Radiofrequency Pulses Delivered in the Vicinity of the Coronary Arteries: Implications for Nonsurgical Transthoracic Epicardial Catheter Ablation to Treat Ventricular Tachy‐cardia. This study evaluates the effects of epicardial RF ablation on the coronary vessels in a canine model. Nonsurgical epicardial catheter ablation is a minimally invasive procedure that has proven to be efficacious for the treatment of VT. This approach is limited by concern regarding the potential adverse effects of RF ablation on the epicardial coronary arteries. After lateral thoracotomy, a multipolar linear ablation catheter was sewn adjacent to or crossing the LAD in nine mongrel dogs. Five of these dogs also had a standard 4‐mm tip ablation catheter sewn adjacent to the LAD. RF pulses were delivered using temperature control. Animals were sacrificed 14 days after ablation for histological analyses. Using the 4‐mm tip catheter, 22 consecutive single lesions of 2.67 ± 0.35 mm depth were studied. The only coronary arterial change seen was replacement of the media with extracellular matrix. Using the linear ablation catheter, 117 pulses were applied to generate 24 linear lesions (3.8 ± 1 mm depth). Replacement of the coronary arterial media with extracellular matrix proliferation was commonly seen, and severe hyperplasia occurred in one artery. Intravascular thrombosis occurred in six arteries. The internal perimeter of the vessel (0.78 ± 0.49 mm vs 1.79 ± 0.83 mm) was the only variable associated with severe arterial damage. The effects of RF ablation delivered adjacent to the LAD were limited to the media but when delivered above the artery, severe intimal hyperplasia and intravascular thrombosis may occur. Susceptibility to damage is inversely proportional to the vessel size.

Nonsurgical Transthoracic Epicardial Approach in Patients with Ventricular Tachycardia and Previous Cardiac Surgery

AbstractIntroduction: The subxyphoid pericardial mapping approach can be used to facilitate catheter ablation of postmyocardial-infarction ventricular tachycardia (post-MI VT), but the presence of dense adhesions is thought to preclude this approach in patients who have previously undergone open-chest cardiac surgery.nAims of the Study: This study reports the first use of a nonsurgical transthoracic epicardial approach in patients with scar-related VT and previous cardiac surgery.nMethods: Five patients with a mean age of 67 ± 10 years, left ventricular ejection fraction (LVEF) of 40 ± 4.3%) and recurrent VT occurring 7 months to 10 years after cardiac surgery underwent combined endocardial and epicardial mapping and ablation during the same session. Because pericardial adhesions were anticipated to be denser in the anterior wall, the nonsurgical transthoracic epicardial puncture was directed to the inferior wall of the left ventricle. Failure to interrupt VT with radio frequency (RF) energy pulses delivered at the best endocardial or epicardial site prompted changing from one approach to the other.nResults: During the epicardial puncture procedure, the contrast medium accumulated in the inferior wall instead of spreading around the cardiac silhouette. The pericardial sac could be entered in all patients, and mapping of the infero-lateral epicardial wall of the left ventricle was feasible. Fourteen VTs were induced, of which 8 could not be mapped because of poor hemodynamic tolerance. Three of the remaining 6 mappable VTs were eliminated by endocardial ablation, 2 required an epicardial RF pulse to be rendered noninducible, and 1 VT was not eliminated. No intra- or postprocedural complications were noted despite full heparinization.nConclusion: Nonsurgical transthoracic epicardial catheter mapping and ablation of epicardial VT related to the inferolateral left ventricular wall are feasible in patients who have previously undergone open- cardiac surgery.

Probability of occurrence of life-threatening ventricular arrhythmias in Chagas' disease versus non-Chagas' disease.

The implantable cardioverter defibrillator (ICD) is highly effective in the treatment of ventricular arrhythmias (VA) responsible for sudden cardiac death. However, the probability of occurrence of these arrhythmic events in presence of cardiomyopathy remains uncertain. The aim of this study was to compare the probability of nonoccurrence of life‐threatening VA in ICD recipients with Chagas versus non‐Chagas heart disease. Over a mean follow‐up of 10.5 months, 53 ICD recipients (mean age = 50.1 years, 48 male) were evaluated. Eleven patients had Chagas heart disease, 19 had idiopathic dilated cardiomyopathy and 23 had ischemic cardiomyopathy. Ventricular tachyarrhythmias with a cycle length < 315 ms were considered life‐threatening. The cumulative probability of nonoccurrence of life‐threatening VA was examined by Kaplan‐Meyer method and the outcomes were submitted to the log rank test. At 2 years, the cumulative probability of life‐threatening VA nonoccurrence was 0 in the Chagas heart disease group versus 40% up to 55 months of follow‐up in the non‐Chagas disease group (P = 0.0097). Among patients with cardiomyopathies of different etiologies, those with Chagas heart disease had the lowest cumulative probability of nonoccurrence of life‐threatening VA, confirming its unfavorable prognosis and the importance of preventive measures against sudden death in this disease.

New perspectives on catheter-based ablation of ventricular tachycardia complicating Chagas' disease: experimental evidence of the efficacy of near infrared lasers for catheter ablation of Chagas' VT.

Chronic Chagas myocarditis can alter the myocardial substrate in a way that facilitates the emergence of fatal VT in a way similar to the long-term consequences of myocardial infarction. Post-myocardial infarction and Chagas VT share many similarities: they are both macroreentrant circuits, entrainable, involving any wall segment from the endocardium to the epicardium. However, as compared to patients with post-MI VT, Chagasic patients tend to be younger and have a higher left ventricular ejection fraction. It is assumed, therefore, that their prognosis is closely related to VT treatment rather than the progression of the myocardial damage caused by the disease itself. Although sudden death is a rare event in patients in NYHA functional class I and II treated with amiodarone, VT recurrence rate is 30% a year. Drug therapy is ineffective for patients with advanced heart failure (100% recurrence rate/40% mortality in 1 year). Open-chest surgery is effective but requires very specialized centers and great expertise making its widespread use unrealistic. The results of combining RF endo/epicardial catheter ablation are still disappointing. Thus, research protocols on the search for new ablation technologies may greatly impact overall mortality in this subset of patients. This review will focus on the limitations of the current catheter-based ablation technology and suggest that an alternative approach is urgently needed. Experimental evidence of the efficacy of near infrared Lasers for catheter ablation will be reported along with investigations of the optical properties of the chagasic myocardium in the near infrared region to indicate that it might be not only feasible but also an appropriate choice to treat these patients.

Reduction of radiation exposure time during catheter ablation with the use of pulsed fluoroscopy

UNLABELLEDnProlonged exposure to radiation during radiofrequency catheter ablation implies a potential risk of radiodermatitis, neoplasm and genetic defects to the patient and to the operator-physician. The use of pulsed fluoroscopy is thought to reduce such a risk because the radiation dose decreases for the same period of time. The aim of the present study was to compare the radiation exposure time during pulse and continuous radiofrequency catheter ablation.nnnMETHODSnProcedures were divided according to the sort of fluoroscopy utilized and the last four cases of atrioventricular (AV) junction ablation, four of atrial flutter, five of atrial tachycardia, 16 of AV node reentrant tachycardia, 16 of AV tachycardia and 10 of ventricular tachycardia in which pulsed and continuous fluoroscopy were utilized were respectively separated into Group I (pulse fluoroscopy) and Group II (continuous fluoroscopy) with 55 patients in each group. Fluoroscopy was generated by the same device in the two groups. Continuous fluoroscopy used 2 mA and automatic kV adjustment (automatic brightness stabilizer) ranging from 70 to 110 kV. Pulsed fluoroscopy was set at 7 squares/s with 25 mA and automatic kV adjustment. Fluoroscopy time was registered by the fluoroscopy device counter.nnnRESULTSnProcedure duration, success rate and complications did not differ between Groups I and II. Fluoroscopy time, however, was 4.4+/-4 min during pulsed fluoroscopy and 27+/-23 min during continuous fluoroscopy (p=0.001).nnnCONCLUSIONnDuring radiofrequency catheter ablation procedures, the use of pulsed fluoroscopy set at 7 squares/s, decreases the radiation exposure time by 80% as compared to continuous fluoroscopy without changing procedure duration and success rate.

Radiofrequency ablation of sustained ventricular tachycardia related to the mitral isthmus in Chagas' disease.

SCANAVACCA, M., et al.: Radiofrequency Ablation of Sustained Ventricular Tachycardia Related to the Mitral Isthmus in Chagas Disease. This case report describes the electrophysiological findings of a 62‐year‐old patient with chronic Chagas disease and two distinct morphologies of sustained ventricular tachycardia that involved a mitral isthmus. Multiple RF applications were necessary to obtain a bidirectional conduction block in the mitral isthmus that was related to the interruption of both tachycardias. After the procedure, the patient presented massive cerebral infarction that progressed to coma and death. Autopsy showed acute and old lesions at the mitral isthmus and recent mitral annulus thrombosis.

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.

Long‐Term Results of Visually Guided Left Ventricular Reconstruction as Single Therapy to Treat Ventricular Tachycardia Associated with Postinfarction Anteroseptal Aneurysm

Visually Guided Left Ventricular Reconstruction for Recurrent VT. Introduction: Postinfarction ventricular tachycardia (VT), anteroseptal aneurysm. and ventricular dysfunction are commonly associated and predict a poor long‐term prognosis. Surgical left ventricular reconstruction, which includes double plication of the anterior and septal wall, can improve ventricular function. This article analyzes the long‐term efficacy of such a procedure to control recurrence of VT in a group of 50 consecutive patients.

Relação entre a persistência da condução pela via lenta nodal após ablação de taquicardia por reentrada nodal e a recorrência clínica

PURPOSE: The aim of this study is to verify whether the persistence of conduction over the slow pathway is related to an increased trend for recurrence. METHODS: Recurrence rate was retrospectively analyzed in 126 patients who underwent slow pathway radiofrequency (RF) catheter ablation during a follow-up of 20±12 months. The ablative procedure was interrupted when AVNRT was no longer induced by atrial stimulation after intravenous infusion of isoproterenol. Ninety-eight patients had no evidence of slow pathway whereas 28 patients persisted with AV node jump and atrial echo beat. RESULTS: There were 15 recurrences: 9% of those who had no evidence of slow pathway (9 of 98 patients) and 21% of those with AV node jump and/or atrial echo beat but this difference was not statistically significant. CONCLUSION: As long as AVNRT cannot be induced by atrial pacing and isoproterenol infusion after slow pathway RF catheter ablation, the presence of AV node jump and/or atrial echo beat does not increase the risk of recurrence of AVNRT.PURPOSEnThe aim of this study is to verify whether the persistence of conduction over the slow pathway is related to an increased trend for recurrence.nnnMETHODSnRecurrence rate was retrospectively analyzed in 126 patients who underwent slow pathway radiofrequency (RF) catheter ablation during a follow-up of 20 +/- 12 months. The ablative procedure was interrupted when AVNRT was no longer induced by atrial stimulation after intravenous infusion of isoproterenol. Ninety-eight patients had no evidence of slow pathway whereas 28 patients persisted with AV node jump and atrial echo beat.nnnRESULTSnThere were 15 recurrences: 9% of those who had no evidence of slow pathway (9 of 98 patients) and 21% of those with AV node jump and/or atrial echo beat but this difference was not statistically significant.nnnCONCLUSIONnAs long as AVNRT cannot be induced by atrial pacing and isoproterenol infusion after slow pathway RF catheter ablation, the presence of AV node jump and/or atrial echo beat does not increase the risk of recurrence of AVNRT.OBJETIVO: Verificar se a persistencia de salto nodal relaciona-se a taxa de recorrencia de taquicardia por reentrada nodal (TRN) apos ablacao com radiofrequencia (RF) da via lenta do no atrioventricular. METODOS: Num seguimento de 20±12 meses, foi analisada a recorrencia de TRN em 126 pacientes consecutivos submetidos a ablacao com RF da via lenta nodal. O criterio de interrupcao do procedimento foi a nao reinducao da TRN, apos estimulacao atrial programada, com e sem isoproterenol intravenoso. Ao final do procedimento, 98 pacientes nao apresentavam salto nodal, e em 28 persistia o salto nodal e/ou o eco atrial. RESULTADOS: Houve recorrencia clinica de TRN em 15 (11%) pacientes: 9 no grupo sem salto nodal e/ou eco atrial e em 6 do grupo que persistiu com salto e/ou eco atrial. A recorrencia tendeu a ser maior no 2o grupo (9% vs 21%), mas nao houve significância estatistica entre os resultados (p=0,09). CONCLUSAO: Desde que a TRN nao possa ser induzida apos a infusao de isoproterenol, a recorrencia espontânea da arritmia apos a ablacao por RF da via lenta nodal nao e diferente entre pacientes que persistem ou nao com salto nodal e/ou eco atrial.