Textbook of Cardiology

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Brugada Syndrome (view source)

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However, most patients with Brugada syndrome are asymptomatic and are under medical attention because of family screening for sudden cardiac death/Brugada syndrome or because a Brugada ECG was found coincidentally.  
However, most patients with Brugada syndrome are asymptomatic and are under medical attention because of family screening for sudden cardiac death/Brugada syndrome or because a Brugada ECG was found coincidentally.  


==ECG tests==
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.


==Diagnosis and treatment==
==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.


*Patients who are symptomatic (unexplained syncopes, ventricular tachycardias or aborted sudden cardiac death) may have a symptom recurrence risk of 2 to 10% per year. In these patients an [[:w:nl:Internal_Cardiac_Defibrillator|ICD]] implant is advisable. Further, life-style advice is given (see below).
==Risk Stratification==
*Some groups advise an electrophysiological investigation (inducibility of ventricular fibrillation) for risk assessment in Brugada patients,<cite>brug2</cite><cite>brug3</cite> but others could not reproduce the predictive value of these tests,<cite>priori</cite><cite>eckhardt</cite> so the value of inducibility is controversial.
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.
*In large studies familial sudden death did not appear to be a risk factor for sudden death in siblings.
*In asymptomatic patients in whom the Brugada ECG characteristics are present (either spontaneously or provoked by fever or sodium channel blockers like ajmaline, procainimde or flecainide) life style advice is given. This advice includes:
**A number of medications should not be taken (including sodium channel blockers and certain anti-depressants and anti-arrhythmics, see [http://www.brugadadrugs.org www.BrugadaDrugs.org])
**Rigorous treatment of fever with paracetamol/Tylenol, as fever may elicit a Brugada ECG and arrhythmias in some patients.
* Spontaneous Type I ECGs do appear to be more prevalent in patients who experienced symptoms.


For a full list of the diagnostic criteria, see <cite>Wilde</cite>
==Treatment==


==Electrocardiographic criteria==
'''"Lifestyle modification":'''
[[Image:Brugada_lead_placement.png|thumb|right|Changed lead positions of leads V3 and V5 to increase the sensitiviy to 'catch' a Brugada pattern on the ECG]]
*All Brugada syndrome patients should avoid drugs that could manifest a type 1 ECG and VF. These drugs are listed on [http://www.brugadadrugs.org www.BrugadaDrugs.org]).
Three ECG repolarization patterns in the right precordial leads are recognized in the diagnosis of Brugada syndrome.
*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.


'''Type I''' is the only ECG criterion that is diagnostic of Brugada syndrome. The type I ECG is characterized by a J elevation >=2 mm (0.2 mV) a coved type ST segment followed by a negative T wave (see figure). Brugada syndrome is definitively diagnosed when a type 1 ST-segment is observed in >1 right precordial lead (V1 to V3) in the presence or absence of a sodium channel–blocking agent, and in conjunction with one of the following:
'''Medication/Other therapies:'''  
*documented ventricular fibrillation (VF)
*[http://www.textbookofcardiology.org/index.php?title=W:nl:Internal_Cardiac_Defibrillator&action=edit&redlink=1 ICD) implantation is first line therapy in Brugada patients with a previous cardiac arrest, [http://www.textbookofcardiology.org/index.php?title=Ventricular_Tachycardia&action=edit&redlink=1 ventricular] tachycardia or cardiac [http://www.textbookofcardiology.org/wiki/Syncope 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).
*polymorphic ventricular tachycardia (VT)
*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.
*a family history of sudden cardiac death at <45 years old
*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.
*coved-type ECGs in family members
*inducibility of VT with programmed electrical stimulation
*syncope
*nocturnal agonal respiration.
The sensitivity of the ECG for Brugada syndrome can be increased with placement of ECG leads in the intercostal space above V1 and V2 (V1ic3 and V2ic3)
 
Electrocardiograms of Brugada patients can change over time from type I to type II and/or normal ECGs and back.
A type III ECG is rather common and is considered a normal variant, but also the Type II is a normal variant (albeit suggestive of Brugada syndrome).
 
A recent study suggests that''' fractionation of the QRS complex''' is a marker of a worse prognosis in Brugada syndrome.<cite>Morita</cite>
 
{| class="wikitable" font-size="90%"
|- style="text-align:center;background-color:#6EB4EB;"
|+'''ST segment abnormalities in the different types of Brugada syndrome'''<cite>Wilde2</cite>
|-
!
!Type I
!Type II
!Type III
|-
!J wave amplitude
|>= 2mm
|>= 2mm
|>= 2mm
|-
!T wave
|Negative
|Positive or biphasis
|Positive
|-
!ST-T configuration
|Coved type
|Saddleback
|Saddleback
|-
!ST segment (terminal portion)
|Gradually descending
|Elevated >= 1mm
|Elevated < 1mm
|-
|}
 
 
<gallery caption="Examples of Brugada syndrome type I">
Image:Brugada_syndrome_type1_example1.png
Image:Brugada_syndrome_type1_example2.png
Image:Brugada_syndrome_type1_example3.png
Image:Brugada_syndrome_type1_example4.png
Image:Brugada_syndrome_type1_example5.png
Image:Brugada_syndrome_type1_example6.jpg|Brugada ECG during ajmaline testing
</gallery>
<gallery caption="Examples of Brugada syndrome type II">
Image:Brugada_syndrome_type2_example1.png
Image:Brugada_syndrome_type2_example2.jpg
</gallery>
 
==External links==
*Cardiogenetics website of the AMC [http://www.cardiogenetica.nl cardiogentica.nl]
*[http://www.brugada.org Brugada.org ]
*[http://www.genereviews.org/servlet/access?id=8888891&key=ghdBRjkdNXE6y&gry=INSERTGRY&fcn=y&fw=E0gK&filename=/profiles/brugada/index.html Genereview Brugada]
*[http://www.brugadadrugs.org Brugada drugs contains lists of medications that should be avoided in patients with Brugada syndrome and medication that can be used to diagnose the syndrome]


==References==
==References==
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