Sunday ECG ACADEMICs
Decoding the ECG in Brugada syndrome:A step towards understanding
By DR. D.P. KHAITAN,
MD (MEDICINE) FCGP (IND) FIAMS (MEDICINE) FICP FICCMD,FIACM, Gayajee, India
@EcgsOnly
@ecgandrhythmRoe @smithECGBlog
▪️In the normal ventricle , the epicardial and endocardial action potentials maintain a harmonious symmetry without disturbing the electrical field balance across the wall –translating on the surface ECG as an isoelectric ST segment , as a part imprint of cardiac electrical journey during repolarization.
▪️A different gesture exists with ‘Brugada syndrome’ , a genetically inherited ECG abnormality. Every Brugada pattern is a whisper of warning from the heart asking for decoding its waves on ECG and its recognition before the life is lost in silence.
▪️To decode Brugada is to hear the language of sodium current – the silent spark in the epicardial territory of RVOT as coved ST elevation in leads V1,V2 and V3 with a recognized pattern on ECG.
▪️The volcano of arrhythmia may erupt at any time , which can end the life suddenly
▪️Every clinician must be acquainted with this abnormal electrical activity occurring in the right ventricle with BrS , signifying its association with high risk of malignant ventricular
arrhythmias , a gigantic turmoil snatching the life from the sufferers
🔦Now see the attached ECG
Findings :
Coved ST elevation in V1-V2 > 2 mm.
This coved upper convex pattern with smooth , oblique descend into an inverted Twave – without an intervening gap in between two.
It is the hallmark of Type 1 Brugada pattern
Early repolarization (ERS) is seen in lateral chest leads V4-V6 as a overlap part.
Prolonged PR interval is also seen , most obvious over lead V3 indicating first degree AV block.
Comments :
Coved ST elevation in >2 mm in right precordial leads (V1-V2) is sufficient enoughto classify the pattern as Type 1 Brugada.
Early repolarization in lateral leads V4-V6 with BrS as an overlapping J-wave syndrome.
Prolonged PR interval here in association reflects extension of sodium channel dysfunction into the conduction system.
✈️Take Home Message
🚦Brugada syndrome (BrS) is fundamentally a channelopathy primarily due to loss-offunction mutations of the cardiac sodium channel (SCN5A → Naᵥ1.5), leading to
reduced INa and conduction delay, most pronounced in the right ventricular outflow tract (RVOT) epicardium.
🚦The RVOT epicardium exhibits a prominent Ito current, making it highly vulnerable to the loss of the action potential dome to the extent of its collapsing (prominent Ito
current reduces the activation of ICa current with the loss of dome pattern). Endocardium retains the dome, while the epicardium loses it, thereby creating a transmural voltage gradient during early repolarization.
🚦The resulting outward current (endo → epi) is directed toward the chest leads
(V1–V3), producing the characteristic coved-type ST-segment elevation available on the ECG to be interpreted.
🚦The basic diagnostic dictum in Type-1 Brugada syndrome – Coved-ST segment elevation > 2 mm > 1 of V1-3 , immediately merging with the following negative T-wave.
🚦Type 2 and Type 3 only serve as pointing clues ; pharmacological challenge with sodium channel blockers or high-lead replacement in needed to unmask the type 1
morphology if it is masked therein.
🚦The resultant transmural voltage gradient is the basis of re-entry mechanism providing the substrate for ventricular tachycardias, explaining the syndrome’s arrhythmogenic potential despite structurally normal hearts.
🚦Recognition of the ECG pattern in the background of clinical context, avoidance of sodium-channel blocking drugs, fever control, and use of ICD therapy in high-risk patients remain the cornerstone of management.
🚦Lastly to say the understanding of Brugada syndrome depends upon how much one grasps its electro-ionic basis , which transforms ECG pattern into a meaningful electrophysiological story.
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Keypoints
@EkgHacks @googledocs @medflutter_ @ECG_BUDDY_ARPI
o Brugada syndrome , first shared globally in 1992 by ‘Brugada brothers’ (Pedro, Josep, and Ramon, three Spanish cardiologists) is a major electrophysiological abnormality
causing sudden cardiac death (SCD) , syncope and even ventricular tachyarrhythmias in young population with no structural heart disease.
o There is a genetically determined ionic derangement over the right ventricular outflow tract (RVOT) epicardial cells to the extent of the loss of harmony in between EPI-ENDO action potentials , endangering the life by setting in of high degree of transmural voltage gradient which might result in ventricular tachyarrhythmias.
o By the further turning of the pages of history it was found to be first described in 1917 in the Philippines as Bengungut referring to sudden death in apparently healthy young males , occurring at night during sleep with revealing no pathological changes on
autopsy as the cause of death. The same disease entity was nomenclatured as ‘Laitai’ (‘death during sleep’) in Thailand, ‘Pokkuri’ (sudden and unexcepted ceased
phenomenon) death syndrome’ in Japan , ‘Dolyeonsa death syndrome’ in Korea , ‘Dream disease’ in Hawai or ‘Sudden Manhood Death Syndome’ in China .
All these nomenclatures indicate the occurrence of death during resting or sleeping hours , suggesting a possible association with Bradycardia and Vagal events.
These incidences point towards the occurrence of this unexplained nocturnal death syndrome in Southeast Asian ethnic group and it is also a fact that this entity is highly prevalent in this global zone.
2. Biostatistics
Its prevalence varies from one in five thousand to one in two thousand.
The age in diagnosis ranging from 2 days to 84 years. It is 8 to 10 times more prominent in males compared to females.
The incidence of SCD in young males is having the highest occurrence those under 40 years of age.
Women and elderly patients are considered to be in lower risk group.
In 1997, Brugada syndrome was recognized as an entity with sudden unexplained nocturnal death syndrome
The first genetic alteration was identified in 1998 (It is well known that BrS is consistent with an autosomal dominant inheritance having variable expressions).
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@EkgHacks @googledocs @medflutter_ @ECG_BUDDY_ARPI Electrophysiology in Brugada syndrome
The following ionic facts must be kept in mind while decoding Brugada syndrome (BrS) on ECG:
@agingdoc1 @TrackYourHeart @CadioArena @official_aimsa
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The ventricle as a whole is dichotomized into two structural and
functional units – accordingly is the appearance of BrS on ECG
The ventricle as a whole is dichotomized into two structural and functional units , such as :
The normal ventricular mass (excluding RVOT epicardial zone).
RVOT epicardium behaves as a separate structural and functional unit. The concept of this structural and functional dichotomized unit is essential to understand the concept
of Brugada syndrome on ECG.
A definite diagnosis of Brugada Syndrome requires demonstration of Type-1 Brugada ECG pattern in V1–V3 or right-sided equivalents (high V1–V2).
By placing the chest electrode
over the right precordial 2nd and 3rd intercostal spaces enhances the sensitivity for detecting coved-ST segment elevation of the Type 1 Brugada syndrome.
The other two types of Brugada are non-diagnostic and possibly warrant further challenge with pharmacological induction.
To Be Noted : Pharmacological assessment has been suggested by some experts in Type 2 / Type 3 ECG patterns, if BrS is having a clinical suspicion. The challenging test with
sodium channel blocking drugs may convert these non-diagnostic forms into the diagnostic Type 1.
The evidence shows that this drug induced subgroup is having extremely low with no increased mortality when a comparison is made with the normal population.
(The sodium channel blocker drugs create an extra conduction delay over the right ventricular outflow tract and also over the underneath endocardium, termed as Depolarization Theory.
And induction creating more transmural gradient across AP/endocardium is termed as
Repolarization Theory : both phenomena may convert suspected ECG into Type 1 ECG pattern).
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@EkgHacks @googledocs @medflutter_ @ECG_BUDDY_ARPI @agingdoc1 @TrackYourHeart @CadioArena @official_aimsa Secondary supporting pointers on ECG
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