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Brugada syndrome

The Brugada syndrome is a genetic disease that is manifest by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death. It is also known as Sudden Unexpected Death Syndrome1 (SUDS), and is the most common cause of death in the young in Thailand and Laos2. more...

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First described in 19923, the Brugada syndrome causes sudden death by causing ventricular fibrillation (a lethal arrhythmia) in the heart.

Genetics and pathophysiology

Brugada syndrome is due to a mutation in the gene that encodes for the sodium ion channel in the cell membranes of the muscle cells of the heart (the myocytes). The gene, named SCN5A, is located on the short arm of the third chromosome (3p21). This condition is inherited in an autosomal dominant pattern.


In some cases, the disease can be detected by observing characteristic patterns on an electrocardiogram, which may be present all the time, or might be elicited by the administration of particular drugs. The pattern seen on the ECG is persistent ST elevations in the electrocardiographic leadsV1-V3 with a right bundle branch block (RBBB) appearance with or without the terminal S waves in the lateral leads that are associated with a typical RBBB. A prolongation of the PR interval (a conduction disturbance in the heart) is also frequently seen.


The cause of death in Brugada syndrome is ventricular fibrillation. While there is no treatment modality that prevents ventricular fibrillation from occurring in this syndrome, treatment lies in termination of this lethal arrhythmia before it causes death. This is done via implantation of an implantable cardioverter-defibrillator (ICD), which continuously monitors the heart rhythm and will defibrillate an individual if ventricular fibrillation is noted.


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All is not well … - Photo Quiz - proximal left anterior descending lesion
From American Family Physician, 11/1/02 by Charles Carter

A 63-year-old man complained of pain in his substernal and epigastric region for the past three weeks. The pain occurred after walking a great distance or after he ate, and it resolved with rest. He experienced no radiation of the pain, and no shortness of breath, nausea, or diaphoresis. The patient reported no cardiac history or family history of coronary artery disease. His medical history was notable for type 2 diabetes mellitus for which he took metformin (Glucophage). Other medications included an antacid and omeprazole (Prilosec). He stopped smoking 10 years ago, but he did have a 20 pack-year history. He was pain-free at the time of the interview. Physical examination was unremarkable. An electrocardiogram was obtained (see accompanying figure).


Based on the history and electrocardiographic findings, this patient most likely has which one of the following conditions?


The answer is E: proximal left anterior descending (LAD) lesion. The electrocardiogram (ECG) shows Wellens' sign in leads [V.sub.2] and [V.sub.3]. There are also nonspecific T-wave abnormalities in the lateral and precordial leads (flipped T waves in I, avL, [V.sub.4]-[V.sub.6]) and a nonpathologic Q wave in lead III.

Dr. Hein J.J. Wellens and colleagues first described this ECG finding in 1982. (1) They identified a subgroup of patients with angina who showed a characteristic biphasic T-wave appearance. Patients in this subgroup had a critical proximal LAD lesion. Seventy-five percent of these patients who did not have surgery progressed to have extensive anterior wall myocardial infarctions. (1) The patient described in this case had a severe LAD lesion diagnosed by angiography.

Early repolarization changes often lead to abnormal appearing ST-T-wave complexes in the precordial leads. They usually occur in young adults and are characterized by an elevated initial portion of the ST segment (J-point elevation), not a biphasic T wave.

There is no evidence of transmural anterior wall myocardial infarction; however, the natural history of Wellens' syndrome is eventual development of this injury.

There is no evidence for hyperkalemia, which presents with peaked T waves in each lead. The Wellens' sign can be mistaken for the U wave often seen with hypokalemia. The important difference is the biphasic nature of the Wellens' T wave. A U wave is concave upward in concordance with the T wave it follows.

Biphasic T waves in leads [V.sub.2] and [V.sub.3] comprise Wellens' sign. This finding is part of the Wellens' syndrome, which includes a history of chest pain, normal or minimally elevated cardiac enzymes, absence of precordial Q waves, no pathologic ST elevation, and no loss of R waves in the precordium. (2) An alternate, and actually more common, T-wave abnormality with proximal LAD lesions is deep inversion in leads [V.sub.2] and [V.sub.3]. (3)

It is important to recognize the biphasic T wave, despite its subtle nature, because it helps identify a high-risk patient who will not do well with conservative management. (1,4) Wellens' sign is unlikely to be diagnosed accurately by computer interpretation. (2) Furthermore, the sign tends to appear during pain-free intervals. (5)

The approach to a patient with nonspecific T-wave abnormalities on ECG often involves cardiac stress testing. If the T-wave abnormality is actually Wellens' sign, stress testing is contraindicated and may provoke a fatal outcome. (2) Prompt cardiology consultation and angiography comprise the appropriate work-up of this important finding.

(1.) de Zwaan C, Bar FW, Wellens HJ. Characteristic electrocardiographic pattern indicating a critical stenosis high in left anterior descending coronary artery in patients admitted because of impending myocardial infarction. Am Heart J 1982;103(4 pt 2):730-6.

(2.) Tandy TK, Bottomy DP, Lewis JG. Wellens' syndrome. Ann Emerg Med 1999;33:347-51.

(3.) Haines DE, Raabe DS, Gundel WD, Wackers FJ. Anatomic and prognostic significance of new T-wave inversion in unstable angina. Am J Cardiol 1983;52:14-8.

(4.) de Zwaan C, Bar FW, Gorgels AG, Wellens HJ. Unstable angina: are we able to recognize high-risk patients? Chest 1997;112:244-50.

(5.) de Zwann C, Bar FW, Janssen JH, Cheriex EC, Dassen WR, Brugada P, et al. Angiographic and clinical characteristics of patients with unstable angina showing an ECG pattern indicating critical narrowing of the proximal LAD coronary artery. Am Heart J 1989;117:657-65.

The editors of AFP welcome submission of photographs and material for the Photo Quiz department. Contributing editor is Marc S. Berger, M.D., C.M. Send photograph and discussion to Marc S. Berger, M.D., C.M., P.O. Box 219, Crystal Beach, FL 34681-0219.


COPYRIGHT 2002 American Academy of Family Physicians
COPYRIGHT 2002 Gale Group

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