International journal of cardiology
-
Editorial Comment
Mutation-specific effects of lidocaine in Brugada syndrome.
Brugada syndrome (BrS) is a hereditary cardiac disease characterized by right bundle-branch block, an elevation of the ST-segment in leads V1 through V3 on the electrocardiogram, and ventricular fibrillation that can lead to sudden cardiac death. Mutations in the cardiac sodium channel gene SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent Na+ channel (Na(v)1.5), are identified in 15-30% of patients with BrS. Most SCN5A mutations lead to a 'loss-of-function' phenotype, reducing the Na+ current during the early phases of the action potential. ⋯ However, the N406S mutation in SCN5A causes distinct gating defects and enhanced intermediate inactivation of Na+ channels, which led to unexpected pharmacological effects of lidocaine in a patient carrying this mutation. In the presence of the N406S mutation, use-dependent block by lidocaine is reduced and recovery from intermediate inactivation is hastened by lidocaine. These findings suggest that lidocaine may improve the Brugada phenotype in patients with N406S by increasing the availability of Na+ channels.
-
Editorial Review
Aortic root dilatation in tetralogy of Fallot long-term after repair--histology of the aorta in tetralogy of Fallot: evidence of intrinsic aortopathy.
The ascending aorta or pulmonary trunk in congenital heart disease may dilate out of proportion to hemodynamic or morphogenetic expectations, may become aneurysmal, and may rupture. A bicuspid aortic valve and/or coarctation of the aorta are consistently associated with ascending aortic and para-coarctation medial abnormalities. Congenital heart diseases such as single ventricle, truncus arteriosus, transposition of the great arteries and tetralogy of Fallot are also associated with aortic medial abnormalities. ⋯ There is no current consensus on beta-blocker administration for limiting progressive dilatation of the aortic root in patients with congenital heart disease and repaired tetralogy of Fallot. Aortic root surgery should be considered for these patients and address aortic regurgitation and or prevent the risk of aortic dissection. Meticulous follow-up of the aortic root after repair, tetralogy of Fallot are thus recommended.