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Brugada Syndrome: Difference between revisions
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''By: Louise R.A. Olde Nordkamp, Arthur A.M. Wilde'' | |||
'' | |||
[[Image:Brugada.png|thumb|right|Typical ECG abnormalities in Brugada syndrome: ST elevation in V1-V3, without ischemia.<cite>Wilde</cite>]] | [[Image:Brugada.png|thumb|right|Typical ECG abnormalities in Brugada syndrome: ST elevation in V1-V3, without ischemia.<cite>Wilde</cite>]] | ||
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==General features== | ==General features== | ||
*The diagnosis is based on ECG findings. | *The diagnosis is based on ECG findings. | ||
*It is an inheritable cardiac arrhythmia syndrome with an autosomal dominant inheritance. | *It is an inheritable cardiac arrhythmia <cite>Brugada2</cite> syndrome with an autosomal dominant inheritance. | ||
*Males are often more symptomatic than females, probably by the influence of sex hormones on cardiac arrhythmias and/or ion channels. | *Males are often more symptomatic than females, probably by the influence of sex hormones on cardiac arrhythmias and/or ion channels. | ||
*The arrhythmias typically occur in patients between 30-40 years of age and often during rest or while sleeping. | *The arrhythmias typically occur in patients between 30-40 years of age and often during rest or while sleeping. | ||
*The right ventricle is most affected in Brugada syndrome, and particularly (but not specifically) the right ventricular outflow tract. | *The right ventricle is most affected in Brugada syndrome, and particularly (but not specifically) the right ventricular outflow tract. | ||
*The prevalence varies between 5-50:10.000, largely depending on the geographic location (especially in some Southeast Asian countries the disease is more prevalent). | *The prevalence varies between 5-50:10.000, largely depending on the geographic location (especially in some Southeast Asian countries the disease is more prevalent). | ||
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==ECG tests== | ==ECG tests== | ||
[[File:PlaatjesBrS_graphs.svg|thumb|right|400px]] | [[File:PlaatjesBrS_graphs.svg|thumb|right|400px|<cite>Brugada2</cite>]] | ||
The ECG in Brugada syndrome is characterized by ST-segment elevations directly followed by a negative T-wave in the right precordial leads (V1-V3) and in leads positioned one or two intercostal space higher. It is referred to as a coved type Brugada ECG, or type 1 ECG, and cannot be explained by electrolyte disturbances, ischemia or structural heart disease. This specific ECG hallmark typically fluctuates over time, and can also be presented as a type 2 or type 3 ECG or even a normal ECG. The type 2 ST-segment elevation has a saddleback appearance with a high takeoff ST-segment elevation of ≥ 2mm, a trough displaying ≥1mm, and then either a positive or a biphasic T wave. Type 3 has either a saddleback or coved appearance with a ST-segment elevation of <1mm (figure 1). Type 2 and 3 are not diagnostic of the BrS. In some patients a type 1 ECG may only be unmasked or modulated by sodium channel blockers (such as ajmaline or flecainide) a febrile state, vagotonic agents, α-adrenergic agonists, β-adrenergic blockers, tricyclic or tetracyclic antidepressants, a combination of glucose and insulin, hyperkalemia, hypokalemia, hypercalcemia, and alcohol or cocaine toxicity. | The ECG in Brugada syndrome is characterized by ST-segment elevations directly followed by a negative T-wave in the right precordial leads (V1-V3) and in leads positioned one or two intercostal space higher. It is referred to as a coved type Brugada ECG, or type 1 ECG, and cannot be explained by electrolyte disturbances, ischemia or structural heart disease. This specific ECG hallmark typically fluctuates over time, and can also be presented as a type 2 or type 3 ECG or even a normal ECG. The type 2 ST-segment elevation has a saddleback appearance with a high takeoff ST-segment elevation of ≥ 2mm, a trough displaying ≥1mm, and then either a positive or a biphasic T wave. Type 3 has either a saddleback or coved appearance with a ST-segment elevation of <1mm (figure 1). Type 2 and 3 are not diagnostic of the BrS. In some patients a type 1 ECG may only be unmasked or modulated by sodium channel blockers (such as ajmaline or flecainide) a febrile state, vagotonic agents, α-adrenergic agonists, β-adrenergic blockers, tricyclic or tetracyclic antidepressants, a combination of glucose and insulin, hyperkalemia, hypokalemia, hypercalcemia, and alcohol or cocaine toxicity. | ||
[[Image:Brugada_syndrome_type1_example2.png|thumb|300px|An example of a Brugada type I ECG]] | |||
==Genetic diagnosis== | ==Genetic diagnosis== | ||
In only ~30% genetic variants can be detected in the SCN5A gene, which results in a loss of function of the cardiac sodium channel function. This impairs the fast upstroke in phase 0 of the action potential and leads to conduction slowing in the heart. In the remaining patients sometimes cardiac calcium channel genes (CACNxxx) or potassium channel genes (KCNxx) are involved, but in most of the Brugada syndrome patients no genetic defects are found. | In only ~30% genetic variants can be detected in the SCN5A<cite>SCN5A</cite> gene, which results in a loss of function of the cardiac sodium channel function. This impairs the fast upstroke in phase 0 of the action potential and leads to conduction slowing in the heart. In the remaining patients sometimes cardiac calcium channel genes (CACNxxx) or potassium channel genes (KCNxx) are involved, but in most of the Brugada syndrome patients no genetic defects are found.<cite>FINGER</cite> | ||
==Risk Stratification== | ==Risk Stratification== | ||
[[File:PlaatjesBrS_pyramid.svg|thumb|right|400px]] | [[File:PlaatjesBrS_pyramid.svg|thumb|right|400px|Risk stratification scheme according to clinical variables in Brugada syndrome | ||
Brugada syndrome patients with symptoms (a history of VT/VF or cardiac syncope) and spontaneous coved-type ECG are at risk for future arrhythmic events. However, risk stratification in asymptomatic Brugada syndrome patients is still ill-defined. Family history of sudden cardiac death, male gender and inducibility of VT/VF during programmed electrical stimulation is not consistently shown to be a risk factor. Therefore, risk stratification is best done by an expert cardio-genetics cardiologist. | <cite>priori</cite>]] | ||
<cite>priori</cite> | Brugada syndrome patients with symptoms (a history of VT/VF or cardiac syncope) and spontaneous coved-type ECG are at risk for future arrhythmic events. However, risk stratification<cite>strat</cite> in asymptomatic Brugada syndrome patients is still ill-defined. Family history of sudden cardiac death, male gender and inducibility of VT/VF during programmed electrical stimulation<cite>PRELUDE</cite> is not consistently shown to be a risk factor. Therefore, risk stratification is best done by an expert cardio-genetics cardiologist.<cite>priori</cite> | ||
==Treatment== | ==Treatment== | ||
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*Fever may also provoke type 1 ECG and VF. Patients with fever are advised to go to the hospital to make an ECG. When ECG changes are present, monitoring is warranted and antipyretics are needed. | *Fever may also provoke type 1 ECG and VF. Patients with fever are advised to go to the hospital to make an ECG. When ECG changes are present, monitoring is warranted and antipyretics are needed. | ||
=== | ===Medication/Other therapies:=== | ||
*[[ICD]] implantation is first line therapy in Brugada patients with a previous cardiac arrest, [ | *[[ICD]] implantation is first line therapy in Brugada patients with a previous cardiac arrest, [[ventricular tachycardia]] or cardiac [[syncope]]. ICD implantation in asymptomatic patients is not advised and needs careful judgement regarding the low annual rate of arrhythmic events and high incidence rate of complications (7.5 per 100 patient-years). | ||
*In Brugada patients with recurrent VF events or ICD shocks, isoproterenol or quinidine are known to be effective for VF suppression in both children and adults. | *In Brugada patients with recurrent VF events or ICD shocks, isoproterenol or quinidine are known to be effective for VF suppression in both children and adults. | ||
*Ablation of a fractionated electrogram in the epicardial right ventricular outflow tract is a promising option for VF suppression in Brugada patients in a small study, but still has to be proven in larger cohorts of Brugada patients. | *Ablation of a fractionated electrogram in the epicardial right ventricular outflow tract is a promising option for VF suppression in Brugada patients in a small study, but still has to be proven in larger cohorts of Brugada patients. | ||