Brugada syndrome overview: Difference between revisions
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==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
Insofar as Brugada syndrome is a relatively newly recognized syndrome, its incidence and prevalence continues to increase. Brugada syndrome is quite common in Southeast Asia where it is endemic, and affects 50 out of every 10,000 individuals. | Insofar as Brugada syndrome is a relatively newly recognized syndrome, its incidence and prevalence continues to increase. Brugada syndrome is quite common in Southeast Asia where it is endemic, and affects 50 out of every 10,000 individuals. It is the second leading cause of death after car accidents among young people in these countries. It has been estimated that Brugada syndrome accounts for 4% of all sudden cardiac deaths and 20% of sudden cardiac deaths among patients with structurally normal hearts. It is 8-10 times more common in men. | ||
==Prevalence== | |||
The prevalence of the Brugada syndrome is estimated at 5-50:10,000, largely depending on geographic location. | |||
==Age== | |||
The average age at the time of initial diagnosis or sudden death is 40 ± 22 years, with the youngest patient diagnosed at 2 days of age and the oldest at 84 years. Brugada syndrome usually becomes apparent in adulthood, although signs and symptoms, including sudden death, can occur any time from early infancy to old age. The mean age of sudden death is approximately 40 years. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of death in babies younger than one year. It is characterized by sudden and unexplained death, usually during sleep. Sudden unexplained nocturnal death syndrome (SUNDS) is a condition characterized by unexpected cardiac arrest in young adults, usually at night during sleep. This condition was originally described in Southeast Asian populations, where it is a major cause of death. Researchers have determined that SUNDS and Brugada syndrome are the same disorder. | |||
==Race== | |||
This condition occurs much more frequently in people of Asian ancestry, particularly in Japanese and Southeast Asian populations. It is the most common cause of sudden death in young men without known underlying cardiac disease in Thailand and Laos<ref>Brugada J, Brugada P, Brugada R. The syndrome of right bundle branch block ST segment elevation in V1 to V3 and sudden death--the Brugada syndrome. Europace. 1999 Jul;1(3):156-66. PMID 11225790 </ref>. In some southeast Asian countries the disease is considered endemic and believed to be the second cause of death among young men (after car accidents). In these countries Brugada syndrome is believed to underly (in part) the 'Sudden Unexpected Death Syndrome' (SUDS). This relation has, however, not been thoroughly investigated and there are almost no epidemiological studies into Brugada syndrome ECGs (apart from Japan). In different Asian countries, different names have been given to SUDS: in the Phillipines it is called ''bangungut'' (to rise and moan in sleep) and in Thailand ''lai tai'' (death during sleep). | |||
==Gender== | |||
Although Brugada syndrome affects both men and women, the condition appears to be 8 to 10 times more common in men. Researchers suspect that testosterone, a sex hormone present at much higher levels in men, may be responsible for this difference. | |||
==Risk Factors: Agents and Scenarios that Provoke the Brugada Syndrome Pattern== | ==Risk Factors: Agents and Scenarios that Provoke the Brugada Syndrome Pattern== | ||
Revision as of 23:40, 14 October 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The Brugada syndrome is a genetic disease that is characterized by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death in young adults, and occasionally in children and infants.
Historical Perspective
The Brugada brothers were the first to describe the characteristic ECG findings and link them to sudden death.
Before that the characteristic ECG findings were often mistaken for a right ventricular myocardial infarction. In 1953 a publication by Oscher mentioned that despite being mistaken for right ventricular myocardial infarction, the ECG findings were not associated with myocardial ischemia.[1]
Although the ECG findings of Brugada syndrome were first reported[2] among survivors of cardiac arrest in 1989, it was only in 1992 that the Brugada brothers[3] recognized it as a distinct clinical entity, causing sudden death by causing ventricular fibrillation.
Pathophysiology
Approximately 20% of the cases of Brugada syndrome have been shown to be associated with mutation(s) 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). Loss-of-function mutations in this gene lead to a loss of the action potential dome of some epicardial areas of the right ventricle. This results in transmural and epicardial dispersion of repolarization. Over 160 mutations in the SCN5A gene have been discovered to date, each having varying mechanisms and effects on function, thereby explaining the varying degrees of penetration and expression of this disorder. [4]
Differentiating Brugada Syndrome from other Diseases
Abnormalities that can lead to ST-segment elevation in the right precordial leads include the following:[5]
- Acute myocardial ischemia or infarction
- Acute myocarditis
- Acute pericarditis
- Acute pulmonary thromboemboli
- Arrhythmogenic right ventricular dysplasia / cardiomyopathy (ARVD/C)[6][7]
- Cardioversion. Brugada-like ECG changes can be observed briefly after direct-current cardioversion. It is currently unclear if this is a sign that the patient is a gene carrier for Brugada syndrome.[8][9][10]
- Cocaine intoxication
- Coronary spasm
- Dissecting aortic aneurysm[11]
- Duchenne muscular dystrophy[12]
- Early repolarization
- Friedreich ataxia
- Heterocyclic antidepressant overdose
- Hypercalcemia[13][14]
- Hyperkalemia[15][16][17]
- Hypothermia, can cause an Osborn wave on the ECG which can sometimes resemble Brugada syndrome[18][19]
- Left ventricular hypertrophy
- Pectus excavatum[20]
- Prinzmetal's angina[21]
- Mediastinal tumor compressing the right ventricular outflow tract (RVOT)
- Right or left bundle-branch block (atypical)
- Right ventricular infarction
- Right ventricular ischemia
- Right ventricular outflow tract compression due to a mediastinal tumor[22]or hemopericardium[23]
- Thiamine deficiency[24]
- Various central and autonomic nervous system abnormalities
- Other conditions that can lead to ST-segment elevation in the right precordial leads
- Early repolarization syndrome
- Other normal variants (particularly in males)
Differentiating Brugada Syndrome from Arrhythmogenic Right Ventricular Dysplasia
Although both Brugada syndrome and Arrhythmogenic Right Ventricular Dysplasia are associated with sudden cardiac death in young patients, the two syndromes are fairly easy to distinguish electrocardiographically and clinically.
Genetics
There is only one gene associated with Brugada syndrome, namely the SCN5A gene, and there is no overlap of the genetic abnormalities associated with Arrhythmogenic Right Ventricular Dysplasia.
Structural Abnormalities of the right Ventricle
While Brugada syndrome is not associated with structural abnormalities in the right ventricle, arrhythmogenic right ventricular dysplasia is associated with fibrofatty infiltration.
Precipitant of Ventricular Arrhythmias
Arrhythmogenic right ventricular dysplasia is associated with monomorphic ventricular tachycardia with a left bundle branch morphology and is precipitated by catecholamines or exercise. In contrast, Brugada syndrome is associated with polymorphic ventricular tachycardia and occurs predominantly during sleep or rest.
Response to Pharmacologic Agents
The EKG abnormalities of Brugada syndrome are enhanced by vagotonic agents, beta-adrenergic blockers, and sodium channel blockers whereas the EKG changes of arrhythmogenic right ventricular dysplasia are constant and do not very with vagotonic agents, beta-adrenergic blockers, or sodium channel blockers.
Epidemiology and Demographics
Insofar as Brugada syndrome is a relatively newly recognized syndrome, its incidence and prevalence continues to increase. Brugada syndrome is quite common in Southeast Asia where it is endemic, and affects 50 out of every 10,000 individuals. It is the second leading cause of death after car accidents among young people in these countries. It has been estimated that Brugada syndrome accounts for 4% of all sudden cardiac deaths and 20% of sudden cardiac deaths among patients with structurally normal hearts. It is 8-10 times more common in men.
Prevalence
The prevalence of the Brugada syndrome is estimated at 5-50:10,000, largely depending on geographic location.
Age
The average age at the time of initial diagnosis or sudden death is 40 ± 22 years, with the youngest patient diagnosed at 2 days of age and the oldest at 84 years. Brugada syndrome usually becomes apparent in adulthood, although signs and symptoms, including sudden death, can occur any time from early infancy to old age. The mean age of sudden death is approximately 40 years. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of death in babies younger than one year. It is characterized by sudden and unexplained death, usually during sleep. Sudden unexplained nocturnal death syndrome (SUNDS) is a condition characterized by unexpected cardiac arrest in young adults, usually at night during sleep. This condition was originally described in Southeast Asian populations, where it is a major cause of death. Researchers have determined that SUNDS and Brugada syndrome are the same disorder.
Race
This condition occurs much more frequently in people of Asian ancestry, particularly in Japanese and Southeast Asian populations. It is the most common cause of sudden death in young men without known underlying cardiac disease in Thailand and Laos[25]. In some southeast Asian countries the disease is considered endemic and believed to be the second cause of death among young men (after car accidents). In these countries Brugada syndrome is believed to underly (in part) the 'Sudden Unexpected Death Syndrome' (SUDS). This relation has, however, not been thoroughly investigated and there are almost no epidemiological studies into Brugada syndrome ECGs (apart from Japan). In different Asian countries, different names have been given to SUDS: in the Phillipines it is called bangungut (to rise and moan in sleep) and in Thailand lai tai (death during sleep).
Gender
Although Brugada syndrome affects both men and women, the condition appears to be 8 to 10 times more common in men. Researchers suspect that testosterone, a sex hormone present at much higher levels in men, may be responsible for this difference.
Risk Factors: Agents and Scenarios that Provoke the Brugada Syndrome Pattern
The electrocardiographic findings of Brugada syndrome are often concealed, but can be unmasked or modulated by a number of drugs and pathophysiological states including (in alphabetical order)[26]:
- A combination of glucose and insulin
- Ajmaline (a diagnostic test agent)
- α-adrenergic agonists
- β-adrenergic blockers
- Cocaine
- Fever. It is for this reason that antipyretic agents are recommended to aggressively treat a fever in the patient with Brugada syndrome.
- Flecainide (a diagnostic test agent)
- Hypercalcemia
- Hyperkalemia
- Hypokalemia
- In large studies, a family history of sudden cardiac death among patients with Brugada syndrome does not appear to be a risk factor for sudden cardiac death in siblings.
- Procainamide (a diagnostic test agent)
- Propranolol intoxication
- Sodium channel blockers (a diagnostic test agent)
- Tetracyclic antidepressants
- Tricyclic antidepressants
- Vagotonic agents that mimic sleep
EKG Characteristics
As shown by the racing below, The EKG characteristics of Bugada syndrome include:
- a) A broad P-wave with some PQ prolongation
- b) J point elevation in the right precordial leads (V1-V3)
- c) Coved ST segment elevation
- d) An inverted T wave
References
- ↑ OSHER HL, WOLFF L (1953). "Electrocardiographic pattern simulating acute myocardial injury". The American Journal of the Medical Sciences. 226 (5): 541–5. PMID 13104407. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Martini B, Nava A, Thiene G, Buja GF, Canciani B, Scognamiglio R, Daliento L, Dalla Volta S. Ventricular fibrillation without apparent heart disease: description of six cases. Am Heart J 1989 Dec;118(6):1203-9 PMID 2589161
- ↑ Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol. 1992 Nov 15;20(6):1391-6. PMID 1309182
- ↑ Napolitano C, Priori SG (2006). "Brugada syndrome". Orphanet journal of rare diseases. 1: 35. doi:10.1186/1750-1172-1-35. PMID 16972995.
- ↑ Takehara N, Makita N, Kawabe J, Sato N, Kawamura Y, Kitabatake A, Kikuchi K (2004). "A cardiac sodium channel mutation identified in Brugada syndrome associated with atrial standstill". Journal of Internal Medicine. 255 (1): 137–42. PMID 14687250. Retrieved 2012-10-13. Unknown parameter
|month=ignored (help) - ↑ Corrado D, Nava A, Buja G, Martini B, Fasoli G, Oselladore L, Turrini P, Thiene G. Familial cardiomyopathy underlies syndrome of right bundle branch block, ST segment elevation and sudden death. J Am Coll Cardiol. 1996; 27: 443–448.
- ↑ Corrado D, Basso C, Buja G, Nava A, Rossi L, Thiene G. Right bundle branch block, right precordial ST-segment elevation, and sudden death in young people. Circulation. 2001; 103: 710–717.
- ↑ Kok LC, Mitchell MA, Haines DE, Mounsey JP, DiMarco JP (2000). "Transient ST elevation after transthoracic cardioversion in patients with hemodynamically unstable ventricular tachyarrhythmia". The American Journal of Cardiology. 85 (7): 878–81, A9. PMID 10758932. Retrieved 2012-10-14. Unknown parameter
|month=ignored (help) - ↑ Gurevitz O, Glikson M (2003). "Cardiac resynchronization therapy: a new frontier in the management of heart failure". The Israel Medical Association Journal : IMAJ. 5 (8): 571–5. PMID 12929296. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Gurevitz O, Lipchenca I, Yaacoby E, Segal E, Perel A, Eldar M, Glikson M (2002). "ST-segment deviation following implantable cardioverter defibrillator shocks: incidence, timing, and clinical significance". Pacing and Clinical Electrophysiology : PACE. 25 (10): 1429–32. PMID 12418739. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Myers GB. Other QRS-T patterns that may be mistaken for myocardial infarction; IV. Alterations in blood potassium; myocardial ischemia; subepicardial myocarditis; distortion associated with arrhythmias. Circulation. 1950; 2: 75–93.
- ↑ Perloff JK, Henze E, Schelbert HR. Alterations in regional myocardial metabolism, perfusion, and wall motion in Duchenne muscular dystrophy studied by radionuclide imaging. Circulation. 1984; 69: 33–42.
- ↑ Douglas PS, Carmichael KA, Palevsky PM (1984). "Extreme hypercalcemia and electrocardiographic changes". The American Journal of Cardiology. 54 (6): 674–5. PMID 6475795. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Sridharan MR, Horan LG (1984). "Electrocardiographic J wave of hypercalcemia". The American Journal of Cardiology. 54 (6): 672–3. PMID 6475794. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Myers GB. Other QRS-T patterns that may be mistaken for myocardial infarction; IV. Alterations in blood potassium; myocardial ischemia; subepicardial myocarditis; distortion associated with arrhythmias. Circulation. 1950; 2: 75–93.
- ↑ Merrill JP, Levine HD, Somerville W, Smith S. Clinical recognition and treatment of acute potassium intoxication. Ann Intern Med. 1950; 33: 797–830.
- ↑ Ortega-Carnicer J, Benezet J, Ruiz-Lorenzo F, Alcázar R (2002). "Transient Brugada-type electrocardiographic abnormalities in renal failure reversed by dialysis". Resuscitation. 55 (2): 215–9. PMID 12413761. Retrieved 2012-10-13. Unknown parameter
|month=ignored (help) - ↑ Osborn JJ. Experimental hypothermia; respiratory and blood pH changes in relation to cardiac function. Am J Physiol. 1953; 175: 389–398.
- ↑ Noda T, Shimizu W, Tanaka K, Chayama K (2003). "Prominent J wave and ST segment elevation: serial electrocardiographic changes in accidental hypothermia". Journal of Cardiovascular Electrophysiology. 14 (2): 223. PMID 12693512. Retrieved 2012-10-13. Unknown parameter
|month=ignored (help) - ↑ Kataoka H. Electrocardiographic patterns of the Brugada syndrome in right ventricular infarction/ischemia. Am J Cardiol. 2000; 86: 1056.
- ↑ Wang K, Asinger RW, Marriott HJ (2003). "ST-segment elevation in conditions other than acute myocardial infarction". The New England Journal of Medicine. 349 (22): 2128–35. doi:10.1056/NEJMra022580. PMID 14645641. Retrieved 2012-10-13. Unknown parameter
|month=ignored (help) - ↑ Tarín N, Farré J, Rubio JM, Tuñón J, Castro-Dorticós J (1999). "Brugada-like electrocardiographic pattern in a patient with a mediastinal tumor". Pacing and Clinical Electrophysiology : PACE. 22 (8): 1264–6. PMID 10461308. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Tomcsanyi J, Simor T, Papp L. Images in cardiology. Haemopericardium and Brugada-like ECG pattern in rheumatoid arthritis. Heart. 2002; 87: 234.
- ↑ Read DH, Harrington DD (1981). "Experimentally induced thiamine deficiency in beagle dogs: clinical observations". American Journal of Veterinary Research. 42 (6): 984–91. PMID 7197132. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Brugada J, Brugada P, Brugada R. The syndrome of right bundle branch block ST segment elevation in V1 to V3 and sudden death--the Brugada syndrome. Europace. 1999 Jul;1(3):156-66. PMID 11225790
- ↑ Antzelevitch C, Brugada P, Borggrefe M, Brugada J, Brugada R, Corrado D, Gussak I, LeMarec H, Nademanee K, Perez Riera AR, Shimizu W, Schulze-Bahr E, Tan H, Wilde A (2005). "Brugada syndrome: report of the second consensus conference". Heart Rhythm : the Official Journal of the Heart Rhythm Society. 2 (4): 429–40. PMID 15898165. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help)