Ackerman, Mayo Clinic, Rochester, Minnesota.
Clinical Characteristics Brugada syndrome (BrS) was described 20 years ago as a new clinical entity characterized by the presence of a typical electrocardiographic (ECG) pattern (right bundle branch block and persistent ST-segment elevation in right precordial leads) and associated with a high risk of sudden cardiac death (SCD).1 Currently, it is believed to be responsible for 12% of SCD cases and 20% of SCD in patients with structurally normal hearts.2 Patients may suffer syncope or Inhibitors,research,lifescience,medical SCD secondary to polymorphic ventricular tachycardia (PVT)/ventricular fibrillation
(VF). However, the majority of patients remain completely asymptomatic. Some of the arrhythmias may occur after large meals, during rest, or while sleeping, believed to be due to high vagal tone.3 The symptoms usually appear around 40 years of age; however, there are reports of patients affected from ages 1 to 84. Males are more often symptomatic than females, probably from the influence of hormones and gender Inhibitors,research,lifescience,medical distribution of ion Inhibitors,research,lifescience,medical channels across the heart. There is little information regarding the pediatric population, but studies performed in children have failed to identify a male predominance, perhaps due to low levels of testosterone in children of both genders.4
The prevalence of the disease is difficult to estimate because the pattern is not always recognized or because it may Dinaciclib chemical structure transiently normalize. Nevertheless, global prevalence varies from 5 to 20 in every 10,000, and it is considered endemic in Southeast Asian countries, where Inhibitors,research,lifescience,medical the prevalence is higher.5 Diagnosis The diagnosis of BrS may be hampered because of incomplete penetrance and dynamic ECG manifestations.6 Originally, three repolarization patterns were described: a) Inhibitors,research,lifescience,medical Type-1 ECG pattern, in which a coved ST-segment elevation ≥ 2 mm is followed by a negative T-wave, with little or no isoelectric separation, with this feature being present in > 1 right precordial lead (from V1 to V3); b) Type-2 ECG pattern, also characterized by
a ST-segment elevation but followed by a positive or biphasic T-wave that results in a saddle-back configuration; c) Type-3 ECG pattern, a right precordial ST-segment elevation ≤ 1 mm either with a coved-type or a saddle-back morphology.7 Montelukast Sodium In 2012, Bayés de Luna et al. reported two specific ECG patterns considered descriptive of BrS.8 However, so far, only the ECG type 1 pattern is the sine qua non BrS diagnosis: J-point elevation of > 2 mm with a coved (downward convex) ST segment (Figure 1).9 Both type 2 and 3 are not considered diagnostic. The ECG type 1 pattern may be spontaneously evident or induced by a provocative drug challenge test using intravenous Class 1A or 1C antiarrhythmic drugs. Flecainide, ajmaline, procainamide, disopyramide, propafenone, and pilsicainide have been used to unmask BrS, but ajmaline and flecainide are the drugs of choice at present.