Sissy Lara de Melo

Ablação com radiofreqüência de extra-sístoles da via de saída do ventrículo direito

OBJECTIVES: To evaluate if radiofrequency catheter ablation is an effective procedure for the treatment of right ventricular outflow tract premature ventricular contractions (RVOT-PVC) and ascertain if it results in an improvement of symptoms. METHODS: A prospective study with 30 consecutive patients (mean age 40 ± 13 years, 25 females), with no apparent structural cardiopathy, with very frequent (mean density of 1,263 ± 593/h) RVOT-PVC, symptomatic for more than one year (mean = 74 months) and resistant to antiarrhythmic drugs (3 ± 1.7, including beta-blockers), who underwent radiofrequency catheter ablation. RESULTS: After the first procedure, there were 23 initial successful cases (76.6%) and 7 initial failures (23.4%). Four patients experienced relapses, two of whom did not undergo the second procedure. The second procedure was carried out in 9 patients (7 initial failures and 2 relapses), and there was success in 5 additional patients, one of them by epicardial access. The final success rate was 80% (24/30), and there were no major complications. After a mean follow-up of 14 ± 6 months, in the successful group there was a reduction greater than 90% in density of premature ventricular contractions (PVC) (24/24; p<0.0001) and a resulting absence of symptoms in the majority of patients (23/24; p<0.001). CONCLUSION: Radiofrequency catheter ablation is a safe and effective treatment for patients with persistent and symptomatic PVC with RVOT morphology.

Ablation of typical atrial flutter: a prospective randomized study of cooled-tip versus 8-mm-tip catheters

OBJECTIVES Both ablation catheters with closed irrigated system and 8mm tip-catheters have been shown to be more effective for typical atrial flutter radiofrequency (RF) ablation when compared to conventional 4 mm tip catheter. Considering the differences in complexity and costs of both systems, a prospective study was designed to compare the efficacy and safety of cooled-tip and 8mm-tip catheters for atrial flutter ablation. METHODS Fifty-two consecutive patients underwent RF ablation of cavotricupsid isthmus (CTI) for the treatment of typical atrial flutter, using catheter with closed irrigation system (n=26) or 8 mm-tip catheter (n=26). The RF pulses were applied point-by-point for 60 seconds, with power limited at 50 w for the irrigated catheter and by temperature control (60 degrees/70 w) for the 8 mm catheter. RESULTS The CTI block was successfully performed in 98.1%. Four patients in the irrigated group needed to switch to the other group. There was no significant difference with regard to ablation parameters, such as total time of RF ablation (591.1+/-309.0 s vs 486.2+/-250.8 s), total procedure duration (86.4+/-23.6 vs 78.1+/-22.5 min) and time of fluoroscopy (17.0+/-6.7 vs 15.4+/-4.6 min). During follow-up of 10.6 months in average, one patient in the irrigated group had recurrence of typical atrial flutter. CONCLUSION Efficacy and safety of CTI ablation was comparable between both techniques (irrigated catheter and 8 mm-tip catheter). The complexity of irrigated catheter makes it less competitive.

Targets and End Points in Cardiac Autonomic Denervation Procedures

Background— Autonomic denervation is an alternative approach for patients with symptomatic bradycardia. No consensus exists on the critical targets and end points of the procedure. The aim of this study was to identify immediate end points and critical atrial regions responsible for vagal denervation. Methods and Results— We enrolled 14 patients (50% men; age: 34.0±13.8 years) with cardioinhibitory syncope, advanced atrioventricular block or sinus arrest, and no structural heart disease. Anatomic mapping of ganglionated plexuses was performed, followed by radiofrequency ablation. Heart rate, sinus node recovery time, Wenckebach cycle length, and atrial-His (AH) interval were measured before and after every radiofrequency pulse. Wilcoxon signed-rank test was used for comparison. Significant shortening of the R-R interval (P=0.0009), Wenckebach cycle length (P=0.0009), and AH intervals (P=0.0014) was observed after ablation. The heart rate elevation was 23.8±12.5%, and the Wenckebach cycle length and AH interval shortening was 18.1±11% and 24.6±19%, respectively. Atropine bolus injection (0.04 mg/kg) did not increase heart rate further. Targeting a single spot of the left side (64% of the patients) or right side (36%) of the interatrial septum was observed to be responsible for ≥80% of the final R-R and AH interval shortening during ablation. Conclusions— Targeting specific sites of the interatrial septum is followed by an increase in heart rate and atrioventricular nodal conduction properties and might be critical for vagal attenuation. The R-R interval, Wenckebach cycle length, and AH interval shortening, associated with a negative response to atropine, could be considered immediate end points of the procedure.

Ablação com RF de arritmia na infância: registro observacional em 125 crianças

BACKGROUND Radiofrequency ablation (RFA) in children is an increasingly common practice. OBJECTIVE To evaluate, in our institution, the results of RFA in children younger than 15 years. METHODS A total of 125 children submitted to RFA between May 1991 and May 2010 were analyzed. RESULTS Sixty-seven (53.6%) children were males, aged between 44 days and 15 years (mean 8.6 ± 3.3 years) with median weight of 31 kg. Heart disease was present in 21 (16.8%) patients. The RFA of accessory pathways (AP) was the most common procedure (62 children - 49.6%). The RFA of nodal reentrant tachycardia (NRT) was the second most common arrhythmia in 27 (21.6%), followed by atrial tachycardia (AT) in 16 (12.8%) and ventricular tachycardias (VT) in 8 (6.4%) children. The success criteria were achieved in 86.9%, 96.1%, 80% and 62.5% of patients undergoing RFA of AP, NRT, AT and VT, respectively. Transient AVB occurred during RFA in 4 (3.2%) and LBBB in 7 (5.6%) children. Twenty-five children underwent a new RFA due to initial failure or recurrence. During the mean follow up of 5.5 ± 3.4 years, 107 (88.4%) remained without recurrence. There was no statistical difference regarding the results and the age at which the patient underwent the procedure. No child had persistent AVB or required a permanent pacemaker. CONCLUSION Catheter ablation is a safe and effective alternative therapy in children with recurrent tachycardias refractory to medical treatment.

Predictors of atrial fibrillation after ablation of typical atrial flutter.

BACKGROUND The occurrence of atrial fibrillation (AF) after successful ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) is an important medical event, but predictors of this event are still controversial. OBJECTIVE To determine the incidence of AF and its predictors in patients undergoing ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL). METHODS Fifty two patients with CTI-AFL underwent ablation from January 2003 to March 2004, in Instituto do Coração (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. RESULTS During the mean follow-up period of 26.2 +/- 9.2 months, 16 (30.8%) patients presented AF. The univariate analysis revealed two clinical variables as predictive of the occurrence of AF after ablation of CTI-AFL for three years or longer (RR: 3.00; p = 0.020). In the multivariate analysis, these factors were independent variables associated with the occurrence of AF after ablation of CTI-AFL. CONCLUSION AF is frequently observed during the follow-up of patients undergoing ablation of CTI-AFL. Persistent CTI-AFL and history of arrhythmia for more than three years are predictors of the occurrence of AF during the clinical follow-up.FUNDAMENTO: La ocurrencia de fibrilacion atrial (FA) tras la ablacion con exito del flutter atrial istmo cavotricuspideo (FLA-ICT) dependiente consiste en un evento de importancia clinica. Los factores predictores de esta ocurrencia todavia son controvertidos. OBJETIVO: Determinar la incidencia de FA y los factores predictores para su ocurrencia en los pacientes sometidos a la ablacion del flutter atrial istmo cavotricuspideo (FLA-ICT) dependiente. METODOS: Cincuenta y dos pacientes portadores de FLA-ICT se sometieron a la ablacion en el periodo de enero de 2003 a marzo de 2004, en el InCor del Hospital de Clinicas de la Facultad de Medicina de la Universidad de Sao Paulo. RESULTADOS: Durante el seguimiento promedio de 26,2 (± 9,2) meses, 16 (30,8%) pacientes presentaron FA. El analisis univariado revelo dos variables clinicos como predictoras de ocurrencia de FA despues de la ablacion del FLA-ICT mayor o igual a tres anos (RR: 3,00; P = 0,020). En el analisis multivariado, estos factores fueron variables independientes asociadas a la ocurrencia de FA tras ablacion del FLA-ICT. CONCLUSION: La FA se observa frecuentemente durante el seguimiento de los pacientes tras la ablacion de FLA-ICT dependiente. El FLA-ICT persistente y la historia de arritmia mayor que tres anos son factores predictores para la ocurrencia de FA durante el seguimiento clinico.

Baroreflex Sensitivity and its Association with Arrhythmic Events in Chagas Disease

Background Sudden death is the leading cause of death in Chagas disease (CD), even in patients with preserved ejection fraction (EF), suggesting that destabilizing factors of the arrhythmogenic substrate (autonomic modulation) contribute to its occurrence. Objective To determine baroreflex sensitivity (BRS) in patients with undetermined CD (GI), arrhythmogenic CD with nonsustained ventricular tachycardia (NSVT) (GII) and CD with spontaneous sustained ventricular tachycardia (STV) (GIII), to evaluate its association with the occurrence and complexity of arrhythmias. Method Forty-two patients with CD underwent ECG and continuous and noninvasive BP monitoring (TASK force monitor). The following were determined: BRS (phenylephrine method); heart rate variability (HRV) on 24-h Holter; and EF (echocardiogram). Results GIII had lower BRS (6.09 ms/mm Hg) as compared to GII (11.84) and GI (15.23). The difference was significant between GI and GIII (p = 0.01). Correlating BRS with the density of ventricular extrasystoles (VE), low VE density (<10/h) was associated with preserved BRS. Only 59% of the patients with high VE density (> 10/h) had preserved BRS (p = 0.003). Patients with depressed BRS had higher VE density (p = 0.01), regardless of the EF. The BRS was the only variable related to the occurrence of SVT (p = 0.028). Conclusion The BRS is preserved in undetermined CD. The BRS impairment increases as disease progresses, being more severe in patients with more complex ventricular arrhythmias. The degree of autonomic dysfunction did not correlate with EF, but with the density and complexity of ventricular arrhythmias.

Fatores preditores de fibrilação atrial após ablação do flutter atrial típico

BACKGROUND The occurrence of atrial fibrillation (AF) after successful ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) is an important medical event, but predictors of this event are still controversial. OBJECTIVE To determine the incidence of AF and its predictors in patients undergoing ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL). METHODS Fifty two patients with CTI-AFL underwent ablation from January 2003 to March 2004, in Instituto do Coração (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. RESULTS During the mean follow-up period of 26.2 +/- 9.2 months, 16 (30.8%) patients presented AF. The univariate analysis revealed two clinical variables as predictive of the occurrence of AF after ablation of CTI-AFL for three years or longer (RR: 3.00; p = 0.020). In the multivariate analysis, these factors were independent variables associated with the occurrence of AF after ablation of CTI-AFL. CONCLUSION AF is frequently observed during the follow-up of patients undergoing ablation of CTI-AFL. Persistent CTI-AFL and history of arrhythmia for more than three years are predictors of the occurrence of AF during the clinical follow-up.FUNDAMENTO: La ocurrencia de fibrilacion atrial (FA) tras la ablacion con exito del flutter atrial istmo cavotricuspideo (FLA-ICT) dependiente consiste en un evento de importancia clinica. Los factores predictores de esta ocurrencia todavia son controvertidos. OBJETIVO: Determinar la incidencia de FA y los factores predictores para su ocurrencia en los pacientes sometidos a la ablacion del flutter atrial istmo cavotricuspideo (FLA-ICT) dependiente. METODOS: Cincuenta y dos pacientes portadores de FLA-ICT se sometieron a la ablacion en el periodo de enero de 2003 a marzo de 2004, en el InCor del Hospital de Clinicas de la Facultad de Medicina de la Universidad de Sao Paulo. RESULTADOS: Durante el seguimiento promedio de 26,2 (± 9,2) meses, 16 (30,8%) pacientes presentaron FA. El analisis univariado revelo dos variables clinicos como predictoras de ocurrencia de FA despues de la ablacion del FLA-ICT mayor o igual a tres anos (RR: 3,00; P = 0,020). En el analisis multivariado, estos factores fueron variables independientes asociadas a la ocurrencia de FA tras ablacion del FLA-ICT. CONCLUSION: La FA se observa frecuentemente durante el seguimiento de los pacientes tras la ablacion de FLA-ICT dependiente. El FLA-ICT persistente y la historia de arritmia mayor que tres anos son factores predictores para la ocurrencia de FA durante el seguimiento clinico.

Interventional Electrophysiology in Patients with Congenital Heart Disease

In the last decade, radio-frequency catheter ablation of atrial and ventricular tachycardia has become progressively common, driven predominantly by increasing success and low complication rates. At the same time, there was no significant development in antiarrhythmic drug effectiveness that still present limited efficacy and frequent side effects. As patients with congenital heart disease that have undergone surgical repair or palliation have been getting older, a wide variety of rhythm disturbances have been detected. Although electrophysiological procedures often are problematic due to the complex anatomy of such patients, a high level of success can be achieved with careful attention to surgical history and modern imaging technology. Thus, nowadays, interventional electrophysiological techniques play a major role in their management.

VT Ablation: Importance of Linear Lesions and Late Potentials

A reentrant mechanism related to a ventricular scar is the main mechanism of monomorphic VT in the setting of structural heart diseases. The surviving muscles in the scar areas are the main targets for VT ablation, identified as fragmented and late potentials. Identification of critical fibers involved in the circuit is usually performed during stable VT by using traditional entraining techniques. However, since many patients present hemodynamic instability, nonsustained VTs, or multiple morphologies, substrate mapping during sinus rhythm is an acceptable strategy for such patients. Electroanatomic mapping is an essential tool for identifying the possible channels that are targeted by endocardial and epicardial RF linear lesions. Such strategy produces a marked reduction in VT recurrences being increasingly applied for patients with unmappable VT and may be combined with other mapping approaches in patients with mappable VTs.

A Sensibilidade do Barorreflexo e sua Associação com Eventos Arrítmicos na Doença de Chagas

Background Sudden death is the leading cause of death in Chagas disease (CD), even in patients with preserved ejection fraction (EF), suggesting that destabilizing factors of the arrhythmogenic substrate (autonomic modulation) contribute to its occurrence. Objective To determine baroreflex sensitivity (BRS) in patients with undetermined CD (GI), arrhythmogenic CD with nonsustained ventricular tachycardia (NSVT) (GII) and CD with spontaneous sustained ventricular tachycardia (STV) (GIII), to evaluate its association with the occurrence and complexity of arrhythmias. Method Forty-two patients with CD underwent ECG and continuous and noninvasive BP monitoring (TASK force monitor). The following were determined: BRS (phenylephrine method); heart rate variability (HRV) on 24-h Holter; and EF (echocardiogram). Results GIII had lower BRS (6.09 ms/mm Hg) as compared to GII (11.84) and GI (15.23). The difference was significant between GI and GIII (p = 0.01). Correlating BRS with the density of ventricular extrasystoles (VE), low VE density (<10/h) was associated with preserved BRS. Only 59% of the patients with high VE density (> 10/h) had preserved BRS (p = 0.003). Patients with depressed BRS had higher VE density (p = 0.01), regardless of the EF. The BRS was the only variable related to the occurrence of SVT (p = 0.028). Conclusion The BRS is preserved in undetermined CD. The BRS impairment increases as disease progresses, being more severe in patients with more complex ventricular arrhythmias. The degree of autonomic dysfunction did not correlate with EF, but with the density and complexity of ventricular arrhythmias.