Many of us have heard of Brugada syndrome, but what exactly is it?
Brugada syndrome is an autosomal dominant gene mutation of SCN5A gene which causes a loss of sodium channel function. If you have taken genetics, the types of mutations to the SCN5A gene include missense, nonsense, and insertion/deletion. These genes cause an imbalance in the depolarizing calcium and sodium currents and potassium replolization current. And the majority of these patients are male of Asian descent. Brugada syndrome is thought to be the cause of the “sudden unexplained nocturnal death syndrome”; which was described in many parts of southeast Asia.
Please know that there is a difference between the Brugada sign and Brugada syndrome.
Brugada sign is the ECG sign without symptoms
Brugada syndrome has the ECG sign with symptoms
The symptoms of Brugada syndrome include:
- Familial sudden cariac arrest death in someone less than 45 years old
- Documented VF or Polymorphic Vtach
- Seizure like activity
- Nocturnal agonal respiration
Increased vagal tone, seen during sleep, is thought to cause more prominent ST elevation which increases the likelihood that the patient goes into an arrhythmia. Some things that can unmask a Brugada sign is fever and medications (sodium channel blockers, fever, beta blockers, ETOH, calcium channel blockers, Eric Clapton’s favorite drug cocaine, etc). Fevers can cause it because there is a premature inactivation of the thermosensitive sodium channels.
There are 3 types of Brugada signs but the most important one is Type 1 which we will discuss.
Type 2 and Type 3 Brugada sign are not as diagnostic as Type 1 Brugada sign/pattern.
ECG changes for Type 1 Brugada sign/patthern
- Coved ST elevation of greater than 2mm in V1-V3 (they look like ski slopes!)
- Pseudo RBBB pattern (RSR’)
- Terminal T wave inversions (TWI)
This 12 lead ECG was sent to me a few years back. It was a 40ish year old male with a fever and the provider called this a STEMI. He has a Type 1 Brugada sign but not the syndrome. The fever unmasked the Brugada pattern. Let’s look into this ECG a bit more.
You can see the RBBB pattern with the RSR’ pattern in V1-V2 with the greater than 2mm of coved ST elevation. There is also terminal T wave inversions which means the end part of the T wave is inverted.
As you can see the ST elevation in Brugada syndrome/sign easily mimics a STEMI but the morphology of the ST elevation gives this away. I always say that ECG interpretation is mostly pattern recognition, because it is so true! Learn these patterns and don’t listen to the doc in the box interpretation. The best treatment for these patients is an ICD.
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–Scopeducation Team (Matt)
Larkin, John, and Mike Cadogan. “Brugada Syndrome.” Life in the Fast Lane • LITFL, 7 Feb. 2021, https://litfl.com/brugada-syndrome-ecg-library/.
Li, Ka Hou Christien, et al. “Brugada Syndrome: A Comprehensive Review of Pathophysiological Mechanisms and Risk Stratification Strategies.” International Journal of Cardiology. Heart & Vasculature, Elsevier, 21 Jan. 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974766/.
Mizusawa , Yuka, and Arthur A.M. Wilde. “Brugada Syndrome.” Circulation: Arrhythmia and Electrophysiology, 1 June 2012, https://www.ahajournals.org/doi/full/10.1161/CIRCEP.111.964577.
Teodorovich, Nicholay, et al. “Vagally Mediated Ventricular Arrhythmia in Brugada Syndrome.” HeartRhythm Case Reports, Elsevier, 12 Sept. 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5420008/#:~:text=Increased%20vagal%20tone%20may%20lead,in%20patients%20with%20Brugada%20syndrome.