Brugada Syndrome

What is Brugada Syndrome?

Brugada Syndrome is a rare developing inherited heart condition, which causes abnormally rapid heart rate and resultant palpitation, followed by fainting and without immediate medical attention leads to fetal condition. The abnormal heart rate is termed as cardiac arrhythmia. The irregular heart beat usually extended to the ventricles and denoted as ventricular arrhythmia.

Heart rate is generated by electric nerve impulse, any sudden abnormal electrical nerve impulse transportation can cause increased heart rate and if it affects the lower chambers of the heart (ventricles), then it terms as ventricular arrhythmia and that may related to Brugada Syndrome. ^{(1, 3)}

Causes

Brugada Syndrome is a genetic abnormality which can develop at any age, but incidence is frequent in adult age. The normal heart is functioning due to proper maintaining of the heart rhythm. Heart rhythms are generated from the pacemaker, which is situated at the upper right chamber (right atrium) and spread to the other chambers via cellular ionic pores/ channels. The different cellular ionic pores like sodium, potassium, and calcium ion charged channels are present in the cardiac muscles and heart pumping out blood though spreading these electrical impulses.

In Brugada Syndrome, the anatomy of the heart is normal, but due to an abnormality in the  spreading of electric impulse through cellular channels, disturbance in heart rate occurs. The SCN5A gene is guided sodium channel to transport impulse, but abnormal mutations in this gene can affect the involved protein that makes up the sodium channel. Therefore, the malfunctioning occurs in the sodium ion channel and disturbed impulse spreading occurs throughout the heart and abnormality in the heart rate is generated.

The presence of single replicating of the distorted gene in each ion channel is sufficient. In most of the cases, one affected parent is responsible to transmit the genetic abnormality to the next generation. ^(1,3,4)

Symptoms

In most of the cases, Brugada Syndrome is asymptomatic in mild stage and no warning symptoms provided for the disturbed heart rhythms cause cardiac arrest. The following are the symptoms of cardiac arrest

• Heart beat becomes stop
• Unconsciousness
• Breathing rate lower down and even stops
• Difficult to find a pulse
• Unexpected collapse

Some cases, individuals may familiar with following symptoms like

• Lose consciousness
• Convulsion or tremor
• Palpitation

The included sign which doctors check during diagnosis are:

• Family history of weird sudden deaths
• Sometimes atrial fibrillation is associated with tachycardia.
• High fever can aggravate the condition.

All the above mentioned sign and symptoms do not differ with other cardiac problem. Therefore, it is necessary to consult with a cardiologist and conduct all the tests which can help to confirm the reason behind the sign and symptoms, as these occur due to Brugada Syndrome or other cardiac problem. (1,4)

Reason behind Life Threatening condition

Unfortunately, all the mortalities due to Brugada Syndrome are related to sudden cardiac arrest without providing previous any warning indication. Often, persistent disturbed cardiac rhythm leads to fast, uncoordinated sequence of cardiac contractions (ventricular fibrillation) and lack of proper electric impulse transport leads pumping cessation of the heart. As unnoticeable symptoms restrict the individual to consult or proper diagnosis of the Brugada Syndrome.

Sometimes, if Brugada Syndrome arises in the newborn, it can be possible in death of infants before one year of their age during sleeping. Therefore, it terms as ‘sudden infant death syndrome’. ^(1,2)

Incidence Rate

Generally, Brugada Syndrome occurs in young or middle aged individual. This can affect both male and female. But males are more susceptible, as it is suspected testosterone in involved in arising symptoms. ⁽¹⁾

Diagnosis

After discussing the family history and discussing about the noticeable sign and symptoms, If doctor expects the possibility of Brugada syndrome, then ECG (electrocardiogram) is conducted and advice to consult with a cardiologist with experienced in genetic cardiac problem.

ECG

The ECG is a graphical representation of an electrical impulse generation in the heart and records the heart rhythm. During this test electrodes are fixed on the left side of the chest, upper and lower limb and attached them by electric wires to the electrocardiograph.

The repetition of this test is conducted with injecting antiarrhythmic medicine such as Ajmaline and flecainide due to any finding of abnormality in ECG. These medicines block sodium channels and provides irregular ECG pattern characteristic of the Brugada syndrome.

Other preferable antiarrhythmic medicines are procainamide or propafenone, which can also divulge an abnormal ECG consequence and express an identification of Brugada syndrome.

The negative test result may refer to further test due to analysis of the risk of Brugada syndrome, but need not to stay hospital for the included tests, such as echocardiography and/or MRI scans to analyzing the other cardiac disorders and reasons of arrhythmia, and blood tests to assess calcium and potassium levels in blood plasma.

Genetic Testing

Genetic testing is conducted for find out the abnormal SCN5A genetic mutation, which involve in the Brugada syndrome. This test may involve patient and parents of the patients also to rule out the source of Brugada syndrome. ^(1,3,4)

Treatment

The treatment modality apply for the high risk patient of Brugada syndrome is implantable cardioverter-defibrillator (ICD).

Implantable cardioverter-defibrillator (ICD)

This is a tiny medical device constantly examine heart rhythm and it sends electrical shocks to the cardiac muscle when required to manage the abnormal heart rhythms. A protective lead is put into the clavicle (collar-bone), which is guided by the taking X-ray images of the chest cavity (the site of the heart). One end of the lead is attached with the ventricles and the other end is attached with shock initiator, which is generally entrenched underneath the skin below the clavicle.

For insertion of the ICD, need to hospital stay for 1 to 2 days. Before inserting the ICD device, the accessibility of risk benefit ratio is important, as an ICD can create complications in some individuals. Therefore, cases to case detail analysis is very important before implanting an ICD to individual with Brugada syndrome. Sometimes, ICD may cause generation of shocks without abnormal heartbeat. It is always advisable that any unusual event after implanting an ICD, discuss with doctor, as he can regulate ICD to lessen this event.

Investigated reports propose that individual who has a normal ECG with no symptomatic disturbances are in little danger of cardiac arrest and may not require an ICD.

Medicinal Therapy

Doctors can prescribe quinidine to avoid producing potentially hazardous heart rhythm. It may also add as additional therapy for individual who previously implanted an ICD. ^(1,3,4)

References

1. Brugada syndrome, NHS Choices; Retrieve from: http://www.nhs.uk/conditions/brugada-syndrome/Pages/Introduction.aspx
2. Brugada syndrome, genetic Home References; Retrieve from:  https://ghr.nlm.nih.gov/condition/brugada-syndrome
3. Brugada syndrome; British Heart Foundation; Retrieve from: https://www.bhf.org.uk/heart-health/conditions/brugada-syndrome
4. Brugada syndrome; Mayo Clinic staff; Retrieve from: http://www.mayoclinic.org/diseases-conditions/brugada-syndrome/basics/definition/con-20034848