Endocardial Approach for Substrate Ablation in Brugada Syndrome

Radiofrequency ablation (RFA) in Brugada syndrome (BrS) has been performed by both endocardial and epicardial. The substrate in BrS is not completely understood. We investigate the functional endocardial substrate and its correlation with clinical, electrophysiological and ECG findings in order to guide an endocardial ablation. Two patients agreed to undergo an endocardial biopsy and the samples were examined with transmission electron microscopy (TEM) to investigate the correlation between functional and ultrastructural alterations. About 13 patients (38.7 ± 12.3 years old) with spontaneous type 1 ECG BrS pattern, inducible VF with programmed ventricular stimulation (PVS) and syncope without prodromes were enrolled. Before endocardial mapping, the patients underwent flecainide testing with the purpose of measuring the greatest ST-segment elevation for to be correlated with the size and location of substrate in the electro-anatomic map. Patients underwent endocardial bipolar and electro-anatomic mapping with the purpose of identify areas of abnormal electrograms (EGMs) as target for RFA and determine the location and size of the substrate. When the greatest ST-segment elevation was in the third intercostal space (ICS), the substrate was located upper in the longitudinal plane of the right ventricular outflow tract (RVOT) and a greatest ST-segment elevation in fourth ICS correspond with a location of substrate in lower region of longitudinal plane of RVOT. A QRS complex widening on its initial and final part, with prolonged transmural and regional depolarization time of RVOT corresponded to the substrate located in the anterior-lateral region of RVOT. A QRS complex widening rightwards and only prolonged transmural depolarization time corresponded with a substrate located in the anterior, anterior-septal or septal region of RVOT. RFA of endocardial substrate suppressed the inducibility and ECG BrS pattern during 34.7 ± 15.5 months. After RFA, flecainide testing confirmed elimination of the ECG BrS pattern. Endocardial biopsy showed a correlation between functional and ultrastructural alterations. Endocardial RFA can eliminate the BrS phenotype and inducibility during programmed ventricular stimulation (PVS)

Endocardial Approach for Substrate Ablation in Brugada Syndrome: Epicardial, Endocardial or Transmural Substrate?

Background: Radiofrequency ablation (RFA) in Brugada syndrome (BrS) has been performed both endocardially and epicardially. The substrate in BrS is thus unclear.Objectives: To investigate the functional endocardial substrate and its correlation with clinical, electrophysiological and ECG findings in order to guide an endocardial ablation.Methods: Thirteen patients (38.7±12.3 years old) with spontaneous type 1 ECG BrS pattern, inducible VF with programmed ventricular stimulation (PVS) and syncope without prodromes were enrolled. Before to endocardial mapping the patients underwent flecainide testing with the purpose of measuring the greatest ST-segment elevation for to be correlated with the size and location of substrate in the electro-anatomic map. Patients underwent endocardial bipolar and electro-anatomic mapping with the purpose of identify areas of abnormal electrograms (EGMs) as target for RFA and determine the location and size of the substrate.Results: When the greatest ST-segment elevation was in the 3rd intercostal space (ICS), the substrate was located upper in the longitudinal plane of the right ventricular outflow tract (RVOT) and a greatest ST-segment elevation in 4th ICS correspond with a location of substrate in lower region of longitudinal plane of RVOT. A QRS complex widening on its initial and final part, with prolonged transmural and regional depolarization time of RVOT corresponded to the substrate locateded in the anterior-lateral region of RVOT. A QRS complex widening rightwards and only prolonged transmural depolarization time corresponded with a substrate located in the anterior, anterior-septal or septal region of RVOT. RFA of endocardial substrate suppressed the inducibility and ECG BrS pattern during 34.7±15.5 months. After RFA, flecainide testing confirmed elimination of the ECG BrS pattern. Endocardial biopsy showed a correlation between functional and ultrastructural alterations in two patients.Keywords: Brugada syndrome; Radiofrequency catheter ablation; Electrocardiography; Mapping; Biopsy.Conclusion: Endocardial RFA can eliminate the BrS phenotype and inducibility during PVS.Fil: Tauber, Pablo E.. Centro Modelo del Corazón; Argentina. Gobierno de Tucumán. Ministerio de Salud. Hospital Centro de Salud "Zenón J. Santillán"; ArgentinaFil: Mansilla, Virginia. Centro Modelo del Corazón; ArgentinaFil: Brugada, Pedro. Free University of Brussels. Cardiovascular Division. Cardiovascular Institute; BélgicaFil: Sanchez, Sara Serafina del V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Honore, Stella Maris. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Elizari, Marcelo. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Chain Molina, Sergio. Centro Modelo del Corazón; ArgentinaFil: Albano, Félix A.. Gobierno de Tucumán. Ministerio de Salud. Hospital Centro de Salud "Zenón J. Santillán"; ArgentinaFil: Corbalán, Ricardo R.. Centro Modelo del Corazón; ArgentinaFil: Figueroa Castellanos, Federico. Clínica Mayo; ArgentinaFil: Alzugaray, Damián. Abbott; Argentin

Correlation between functional and ultrastructural substrate in Brugada syndrome

Brugada syndrome (BS) was reported for the first time in 1992 and is associated with an ST-segment elevation in the right precordial leads in the absence of any demonstrable structural heart disease, as well as with sudden cardiac death due to ventricular fibrillation (VF).1 A patent type 1 electrocardiogram (ECG) is diagnostic of BS and is characterized by a coved ST-segment elevation of ≥2 mm followed by a negative T wave in >1 right precordial lead (V1 to V3) in the presence or absence of a sodium channel–blocking agent, and in conjunction with 1 of the following: documented VF, polymorphic ventricular tachycardia (VT), a family history of sudden cardiac death at <45 years of age, coved-type ECGs in family members, inducibility of VT/VF with programmed electrical stimulation, syncope, or nocturnal agonal respiration.2 An autosomal dominant disease with incomplete penetrance, BS has been linked to mutations in SCN5A, the gene encoding the alpha subunit of the cardiac sodium channel. Still, SCN5A mutations have been reported in only approximately 20% of patients with BS diagnosed on the basis of clinical criteria, suggesting that other genetic defects or other disease mechanisms may give rise to this clinical picture.Fil: Tauber, Pablo E.. Provincia de Tucumán. Sistema Provincial de Salud de Tucumán. Hospital Centro de Salud "Zenonj, Santillán"; ArgentinaFil: Mansilla, Virginia. Centro Modelo de Cardiología; ArgentinaFil: Mercau Torres, Guillermo Adolfo. Centro Modelo de Cardiología; ArgentinaFil: Albano, Félix. Provincia de Tucumán. Sistema Provincial de Salud de Tucumán. Hospital Centro de Salud "Zenonj, Santillán"; ArgentinaFil: Corbalán, Ricardo R.. Centro Modelo de Cardiología; ArgentinaFil: Sanchez, Sara Serafina del V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Departamento de Biología del Desarrollo | Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas. Departamento de Biología del Desarrollo; ArgentinaFil: Honore, Stella Maris. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Departamento de Biología del Desarrollo | Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas. Departamento de Biología del Desarrollo; Argentin