Brugada Syndrome
I. Clinical Features
II. Perspective
GLOSSARY
Brugada P. Brugada described the syndrome and its electro-cardiographic changes.
sodium cardiac channels cardiac cells possess channels through which sodium and potassium flow inward and outward; the exchange of positive and negative charge produces a small current.
syncope temporary loss of consciousness caused by lack of blood supply to the brain; fainting describes a simple syncopal attack.
ventricular fibrillation the heart muscle does not contract but quivers; therefore, there is no heartbeat (cardiac arrest) and no blood is pumped out of the heart; death occurs within minutes if the abnormal heart rhythm is not corrected.
PEDRO AND JOSEP BRUGADA DESCRIBED A cardiac condition in 1992 characterized by a typical ECG pattern and a high incidence of sudden death partic¬ularly in younger individuals. The Brugada syndrome is a congenital disorder of sodium cardiac channel function. It is prevalent in Southeast Asia. Rare deaths have occurred during sleep sometimes associated with nightmares. The syndrome has variety of names in different countries: Bangungut (scream followed by sudden death) in the Philippines, Lai Tai in Thailand, and Pokkuri (unexpec¬ted death at night) in Japan. Apparently in Thailand unexplained sudden cardiac death is the leading cause of death in young men, and approximately 40% of these patients have a family history of sudden deaths; an estimated incidence of 1 sudden death per 1000 persons per year. The Brugada VCG phenotype has been estimated to be up to 1.4% in Japan The typical ECG pattern may be intermittent, and is found in 0.15% of Japanese adults, which is associated with a greater then 50-fold increase in the risk of unexpected death; the incidence is reportedly ninefold higher in Japanese men than in women.
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- I. CLINICAL FEATURES
Symptoms, particularly syncope and sudden death, usually appear between the ages of 40 and 50. These symptoms occur with no warning. In one study of 163 patients in which ventricular fibrillation occurred in 22% percent, the following observations were made: 12:1 male to female ratio, 58% of Asian origin, and mean age at first abnormal heart rhythm detected was 22–65, but occurred more often in the 40–50 age group. Most of these patients had a family history of syncope, sudden death, or abnormal ECG changes. - II. PERSPECTIVE
The exact mechanism of the electrocardiographic changes and the development of ventricular fibrillation and sudden death remain undetermined. Electrically active cardiac cells possess sodium channels; an outward sodium current is counterbalanced by an inward sodium current. It appears that in this syndrome the inward current is attenuated and some of the electrocardiographic features can be partly explained based on changes in sodium currents. The syndrome is a disorder of sodium cardiac channel func¬tion that triggers the electrocardiographic changes and malignant arrhythmias, particularly ventricular fibrillation. Mutations in a gene responsible for the sodium chan¬nel have been identified in some families with this syn¬drome. More than three different mutations on the cardiac sodium channel gene SCN5A on chromosome 3 have been described. Mutations on other genes are being sought. Further research is required in this area and its results are of extreme importance to prevent deaths in young individuals. - BIBLIOGRAPHY
Antzelevitch, C., Brugada, P., Brugada, J., Brugada, R., Towbin, J. A.,