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Brugada Syndrome

SUNDS

Brugada syndrome is a genetic disease that is characterized by raised ST segment in the right precordial leads, complete or incomplete right bundle branch block and susceptibility to ventricular tachyarrhythmias and sudden cardiac death.


Presentation

The patients suffering from Brugada syndrome may present to a doctor with various complaints, however, most frequently, these complaints are related to cardiovascular system and/or alterations in electrocardiographic (ECG) patterns.

Syncope is one of the most common manifestations of Brugada syndrome.

Cardiac arrest is another common presentation in these patients.
The patients of Brugada syndrome sometimes complain of nightmares.

Atrial fibrillation is the presentation in about 20% of the cases of Brugada syndrome [7].

Sometimes fever is reported and it also triggers the cardiac events in patients of Brugada syndrome.

Heart murmurs are also present in Brugada syndrome.

Fatigue
  • A previously healthy 29-year-old man was admitted to our hospital, with a 4-day history of fever ( 39 C), rigours, diaphoresis, fatigue and retro-orbital headache. On examination, he was febrile (37.8 C) and tachycardic (110 bpm).[ncbi.nlm.nih.gov]
  • Hospital due to fatigue and chest discomfort. Laboratory findings showed that WBC count and C-reactive protein were increased. Echocardiographic finding was normal. The patient was admitted with a diagnosis of pericarditis.[ncbi.nlm.nih.gov]
Tachycardia
  • We present a case of a symptomatic patient with Brugada syndrome, who had sustained right ventricular outflow tract tachycardia after pronounced exercise-induced ST segment elevation in V1 and V2.[ncbi.nlm.nih.gov]
  • This report documents a case of Brugada syndrome and polymorphic ventricular tachycardia-ventricular fibrillation not initially recognized in a patient taking nortriptyline and experiencing syncope.[ncbi.nlm.nih.gov]
  • A model including the previous 4 main clinical variables (1, sudden cardiac death or syncope; 2, spontaneous type I electrocardiogram; 3, sinus node dysfunction and/or atrial tachycardia; and 4, conduction abnormality) had a high predictive power (C:[ncbi.nlm.nih.gov]
  • Twenty years ago, he underwent radiofrequency catheter ablation for idiopathic sustained monomorphic ventricular tachycardia (VT) with an RBBB and superior axis pattern. The VT was inducible by programmed stimulation and entrained by rapid pacing.[ncbi.nlm.nih.gov]
  • The typical aspect of BS occurred after introduction of propafenone for the prevention of atrioventricular tachycardia. We discuss the recognition of this rare association, the proarrhythmic effects of some drugs, treatment options, and prognosis.[ncbi.nlm.nih.gov]
Heart Disease
  • A ventricular septal defect is a common congenital heart disease, in which genetic defects play a significant role.[ncbi.nlm.nih.gov]
  • He presented with the cove-shaped ST elevation of 2 mm in lead V1 with typical CRBBB and lacked structural cardiomyopathy and coronary heart disease.[ncbi.nlm.nih.gov]
  • Brugada syndrome is a rare genetic disorder mostly affecting young subjects without any underlying heart disease.[ncbi.nlm.nih.gov]
  • Brugada syndrome is an inherited heart disease without structural abnormalities that is thought to arise as a result of accelerated inactivation of Na channels and predominance of transient outward K current to generate a voltage gradient in the right[ncbi.nlm.nih.gov]
  • In 1992, Brugada and Brugada first described a new entity, which became known as Brugada syndrome, that is associated with a high risk of ventricular arrhythmias and sudden cardiac death in patients without structural heart disease.[ncbi.nlm.nih.gov]
Pericardial Friction Rub
  • Acute pericarditis may appears with chest pain, fever, pericardial friction rub, and cardiac tamponade. Moreover, widespread ST segment changes occur due to involvement of the underlying epicardium.[ncbi.nlm.nih.gov]

Workup

Brugada syndrome requires complete work-up and laboratory investigations for proper diagnosis. The investigations relevant to Brugada syndrome are listed below:

  • Genetic testing has an important role in the diagnosis of the patients of Brugada syndrome. In addition to the diagnosis, genetic testing can help in identifying the relatives who are at risk for developing Brugada syndrome. [8]
  • Electrocardiography (ECG) is the key investigation for the patients of Brugada syndrome. This is because some patients of Brugada syndrome may apparently be asymptomatic but still have the underlying electrocardiographic changes of this disease. For diagnostic purposes, these changes can also be induced by administration of some anti-arrhythmic drugs. Brugada syndrome has three different electrocardiographic patterns: ST-elevation (type 1), Saddleback pattern (type 2), A combination of type 1 or type 2.
  • Brugada syndrome can be investigated by inducing arrhythmias with the use of electro-physiologic studies (EPS).
  • Serum calcium and potassium levels should be evaluated because variations in their levels can produce the same electrocardiographic patterns as commonly seen in Brugada syndrome.
  • Creatine kinase MB (CK-MB) and troponin levels should be evaluated to rule out any underlying heart condition e.g. acute coronary syndrome (ACS).
  • Echocardiography and Magnetic resonance imaging (MRI) are used to rule out any arrhythmogenic condition that mimics Brugada syndrome.
Bicytopenia
  • Laboratory work up revealed bicytopenia (white cell count 1.37 10(9)/L, platelets 60 10(9)/L) and an increase in C reactive protein (9 mg/dL). The ECG showed ST segment elevation in V1, V2 and V3 leads.[ncbi.nlm.nih.gov]
Right Bundle Branch Block
  • Negative voltage gradient (-2.5 to -6.0 mV) between epicardium and endocardium of the RVOT was observed in 8 of 12 BrS patients, not present in patients with right bundle branch block or in controls.[ncbi.nlm.nih.gov]
  • Here, we reported an unusual case of electrical storm (ES) of ventricular fibrillation (VF) caused by BrS with complete right bundle-branch block (CRBBB) in a 75-year-old male patient.[ncbi.nlm.nih.gov]
  • , 1998 , vol. 97 (pg. 457 - 460 ) [35] Familial cardiomyopathy underlies syndrome of right bundle branch block, ST segment elevation and sudden death, J Am Coll Cardiol, 1996 , vol. 27 (pg. 443 - 448 ) [36] Pathologic substrates of right bundle branch[doi.org]
  • Brugada Syndrome (BrS) is a cardiac disorder characterized by incomplete right bundle-branch block and ST elevations in the anterior precordial leads especially V1 -V3 , associated with an increased risk for sudden cardiac death (SCD) in young adults.[ncbi.nlm.nih.gov]
  • EKG Right bundle branch block; persistent ST-segment elevation in V1 to V3, unexplained by electrolyte disturbances; ischaemia; structural heart disease. Management Implantable defibrillator.[medical-dictionary.thefreedictionary.com]

Treatment

The best option for the treatment of syncope and cardiac arrest in the patients of Brugada syndrome is the placement of an automatic implantable cardiac defibrillator (ICD). As mentioned earlier, the patients suffering from Brugada syndrome usually die of ventricular fibrillation. If a defibrillating device is in place, episodes of ventricular fibrillation will be promptly reversed and the patient’s life will be saved.

Recent studies have shown that quinidine decreases the episodes of ventricular defibrillation [9]. It may also be used for the treatment of Brugada syndrome in selected cases.

Regular exercise should be stopped as it increases the vagal tone, thereby increasing the risk of ventricular fibrillation.
Long term follow up is necessary for all the patients suffering from Brugada syndrome.

Prognosis

Prognosis depends largely upon the long term proper follow-up. Prognosis is good with proper treatment and management.

Without treatment, sudden cardiac death occurs in men under 40 years of age. With proper placement of implanted cardiac defibrillator, life expectancy and quality of life are improved.

The mean age of sudden death in patients suffering from Brugada syndrome is 41+/- 15 years [10].

Etiology

Brugada syndrome is primarily caused by mutations in SCN5A gene, although mutations in other genes are also seen in some cases [5]. Variants of Brugada syndrome can be caused by the mutations in the genes that code subunits of the L-type calcium channel (CACNA1C and CACNB2).

Some cases of Brugada syndrome also carry mutations in GPD1-L and SCN1B genes. Besides, some conditions and diseases can exaggerate or unmask electrocardiographic changes of Brugada syndrome. Some of them are listed below.

  • Fever can cause variations in electrocardiographic (ECG) pattern in patients of Brugada syndrome [6].
  • Potassium level homeostasis is of prime important in cases of Brugada syndrome. This is because both hypokalemia and hyperkalemia can cause exaggeration of Brugada syndrome.
  • As with potassium, monitoring of the calcium level is also important in cases of Brugada syndrome because fluctuations of calcium level can exacerbate the condition.
  • Alcohol or cocaine abuse also causes exacerbation of the condition.
  • Medications like sodium channel blockers, vagotonic agents, alpha adrenergic agonists, beta adrenergic blockers, heterocyclic antidepressants, and a combination of glucose and insulin cause worsening of Brugada syndrome and associated electrocardiographic changes.

Epidemiology

Brugada syndrome is predominantly a disease of Asian people. It is much less common in the Western world. It is also much more prevalent in men as compared to women [4].

Sex distribution
Age distribution

Pathophysiology

Several different mutations can result in Brugada syndrome. The underlying pathophysiology therefore varies with different genes. The voltage gated sodium channels of the heart are encoded by the SCN5A gene. Therefore, when the mutation is in the SCN5A gene - the most common mutation in Brugada syndrome - the cardiac voltage gated sodium channels do not function normally.

Abnormal voltage-gated sodium channels directly affect the cardiac action potential by reducing the sodium current available during the phases 0 (upstroke) and 1 (early repolarization). This reduction in sodium current then affects the endocardium of the right ventricle and leads to the clinical manifestations as well as the electrocardiographic variations that characterize Brugada syndrome.

The T wave remains upright and causes a saddleback electrocardiographic pattern when the usual time duration of repolarization is not changed.

Mutations in Glycerol-3-phosphate dehydrogenase 1-like (GPD1L) gene are also seen in some patients of Brugada syndrome. This gene acts as ion channel modulator in the heart muscle.

Prevention

There are no guidelines for prevention of Brugada syndrome.

Summary

Brugada syndrome is a clinic-pathological entity that is characterized by an increased risk of sudden cardiac death as well as certain electrocardiographic (ECG) changes in the heart; most commonly the elevation of the ST segment in the precordial leads.

Brugada syndrome is a genetically pre-determined condition. The pattern of inheritance is autosomal dominant in as many as 50% of the familial cases. Brugada syndrome is the major cause of sudden unexplained death syndrome (SUDS) [1].

It is known to be one of the major causes of sudden death in young men without any previously diagnosed cardiac disorders [2].

Sudden death in Brugada syndrome results from ventricular fibrillation and arrhythmias. Electrocardiographic changes are observed in the patients who survive cardiac arrest [3].

Patient Information

Brugada syndrome is a genetic disease that affects the heart at a cellular level. In some patients, it produces no symptoms and remains undetected. In others, it causes symptoms related to the heart.

The patients who receive proper treatment and follow-up have a good prognosis. If untreated, it can cause sudden death in young patients (below 40 years of age) even in the absence of other heart diseases.

References

Article

  1. Nademanee K, Veerakul, G, Nimmannit, S. Arrhythmogenic marker for the sudden unexplained death syndrome in thai men. Circulation. 1997;96(8):2595-2600.
  2. Brugada J, Brugada, P, Brugada, R. The syndrome of right bundle branch block ST segment elevation in V1 to V3 and sudden death--Brugada syndrome. Europace. 1999;1(3):156-166. 
  3. Martini B, Nava, A,Thiene, G. Ventricular fibrillation without apparent heart disease: description of six cases. Am Heart J. 1989;118(6):1203-1209.
  4. Antzelevitch C, Brugada, P, Brugada, J, Brugada, R. Brugada syndrome:from cell to bedside. Curr Probl Cardiol 2005;30(1):9-54.
  5. Kapplinger J, Tester, DJ, Alders, M, Benito, B, Berthet, M, Brugada, J. An international compendium of mutations in the SCN5A encoded cardiac sodium channel in patients referred for Brugada syndrome genetic testing. Heart Rhythm. 2010;7(1):33-46.
  6. Amin AS, Klemens CA, Verkerk AO, et al. Fever-triggered ventricular arrhythmias in Brugada syndrome and type 2 long-QT syndrome. Netherlands heart journal : monthly journal of the Netherlands Society of Cardiology and the Netherlands Heart Foundation. Mar 2010;18(3):165-169.
  7. Bordachar P, Reuter, S, Garrigue, S, Cai, X, Hocini, M, Jais, P, et al. Incidence, clinical implications and prognosis of atrial arrhythmias in Brugada syndrome. Eur Heart J. 2004;25(10):879-884.
  8. Kaufman ES. Genetic testing in Brugada syndrome. Journal of the American College of Cardiology. Oct 9 2012;60(15):1419-1420.
  9. Belhassen B, Glick, A, Viskin, S. Efficacy of quinidine in high-risk patients with Brugada syndrome. Circulation. 2004;110(13):1731-1737.
  10. Antzelevitch C, Brugada, P, Borggrefe, M, Brugada, J, Brugada, R, Corrado, D, et al. Brugada syndrome: report of the second consensus conference: endorsed by the Heart Ryhthm Society and the European Heart Rhythm Association. Circulation. 2005;111(5):659-670.

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Last updated: 2018-06-22 08:04