RESUMO
BACKGROUND: Brugada syndrome is a genetic heart disease with autosomal dominant inheritance. Family screening commonly detects one parent responsible for transmission of the disease. AIMS: To describe atypical transmission of Brugada syndrome. METHODS: Between 2001 and 2007, systematic screening, including an electrocardiogram, ajmaline challenge and DNA sequencing of the SCN5A gene, of the first-degree relatives of 62 probands with Brugada syndrome was performed (Programme Hospitalier de Recherche Clinique). RESULTS: In two families, both parents transmitted Brugada syndrome to their offspring. In the first family, the proband presented Brugada electrocardiogram features with ajmaline challenge and carried a new SCN5A mutation (p.V1281F). The mutation was also identified in the mother, who had a type 1 aspect on inferior leads with ajmaline. The proband's father presented a typical Brugada electrocardiogram pattern on lead V2 with ajmaline and no SCN5A gene mutation. In the second family, the proband was a boy aged 2.5 years who had been resuscitated from sudden cardiac death. Ajmaline challenge revealed a typical Brugada electrocardiogram pattern in both parents but with no mutation in the genes studied. CONCLUSION: Family studies should always be exhaustive and discovery of one parent with Brugada syndrome does not eliminate the need for screening of the other parent.
Assuntos
Síndrome de Brugada/genética , Heterozigoto , Mutação , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Adolescente , Adulto , Ajmalina , Antiarrítmicos , Síndrome de Brugada/complicações , Síndrome de Brugada/diagnóstico , Síndrome de Brugada/terapia , Pré-Escolar , Análise Mutacional de DNA , Morte Súbita Cardíaca/etiologia , Morte Súbita Cardíaca/prevenção & controle , Eletrocardiografia , Técnicas Eletrofisiológicas Cardíacas , Feminino , Triagem de Portadores Genéticos , Predisposição Genética para Doença , Testes Genéticos/métodos , Hereditariedade , Humanos , Masculino , Linhagem , Fenótipo , Valor Preditivo dos Testes , Ressuscitação , Adulto JovemRESUMO
BACKGROUND: Ajmaline challenge is commonly used for the diagnosis of Brugada syndrome. A slow infusion rate has been recommended in view of the proarrhythmic risk, but the diagnostic value of various infusion rates has not been investigated. AIMS: To compare rapid and slow ajmaline infusion rates and to assess the proarrhythmic risk. METHODS: The first part of this study prospectively compared rapid and slow infusion rates in terms of results and ventricular arrhythmias. Thirty-two patients (mean age 41±12 years; 26 men) received the two ajmaline challenges on different days. According to randomization, ajmaline (1 mg/kg) was infused at 1 mg/sec or over 10 minutes. The second part of the study retrospectively assessed the prevalence of ventricular arrhythmia during 386 challenges performed at a rapid infusion rate. RESULTS: No differences were observed between rapid and slow tests. All patients diagnosed as positive or negative with one test obtained the same result with the other test. Ventricular premature beats were observed in five of 32 patients during the slow challenge and in four of 32 patients during the rapid challenge. No sustained ventricular arrhythmias were observed. Analysis of the 386 tests revealed four episodes of ventricular arrhythmia (two complex ventricular premature beats, one non-sustained ventricular tachycardia and one ventricular fibrillation). CONCLUSION: Slow and rapid infusions of ajmaline have identical diagnostic performances on suspected Brugada electrocardiograms. Owing to the risk of severe proarrhythmia, a slow infusion rate, allowing early discontinuation, should be recommended.