[Severe cardiac arrhythmias]. / Les troubles du rythme cardiaque sévères.

Cardiac arrhythmias are a common cause of admission in the emergency department. Among these, atrio-ventricular conductive disorders and malignant ventricular arrhythmias are among the most severe, requiring prompt and appropriate management to ensure the best prognosis. Knowledge of the pathophysiology and etiology causing these arrhythmias is mandatory in order to understand its management, acute and chronic, and to facilitate the dialogue between emergency physicians and cardiologists.

Les arythmies cardiaques sont une cause fréquente d'admission aux urgences. Parmi celles-ci, les troubles conductifs atrio-ventriculaires et les arythmies ventriculaires et supraventriculaires malignes sont à classer parmi les plus sévères. Elles nécessitent une prise en charge rapide et appropriée afin de garantir le meilleur pronostic possible aux patients. La connaissance de la physiopathologie et des étiologies engendrant ce type d'arythmie est nécessaire afin d'en comprendre la prise en charge, aiguë et chronique, et de faciliter le dialogue entre urgentistes et cardiologues.

Reduced Penetrance and Variable Expression of SCN5A Mutations and the Importance of Co-inherited Genetic Variants: Case Report and Review of the Literature.

Mutations in the SCN5A gene are responsible for multiple phenotypical presentations including Brugada syndrome, long QT syndrome, progressive familial heart block, sick sinus syndrome, dilated cardiomyopathy, lone atrial fibrillation and multiple overlap syndromes. These different phenotypic expressions of a mutation in a single gene can be explained by variable expression and reduced penetrance. One of the possible explanations of these phenomena is the co-inheritance of genetic variants. We describe a family where the individuals exhibit a compound heterozygosity in the SCN5A gene including a mutation (R1632H) and a new variant (M858L). Individuals with both the mutation and new variant present with a more severe phenotype including spontaneous atrial tachyarrhythmia at young age. We give an overview of the different phenotypes of "SCN5A disease" and discuss the importance of co-inherited genetic variants in the expression of SCN5A disease.