An often sad tale…

There are upsetting cases of athletes who just drop, the marathon runner who collapses. Why does this happen to these people, when they are pushing themselves to the absolute limit and enduring the ultimate in stress testing…. daily?

***WARNING, SOME MAY FIND THE VIDEO BELOW DISTRESSING!***

We have seen this on our ICU several times, all in young, fit patients. The key for them was that they got attention IMMEDIATELY!

It can happen to anyone…the article below, from admittedly not the greatest source of medical information, prompted me to promote this:

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What is Brugada Syndrome?

The Sun’s definition:

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Here is a fabulous little presentation done by a 15 year old on the topic:

Here is a more advanced look at this arrhythmia

Have a look at this video presentation as added knowledge base

So…the ‘Nitty Gritty’!

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Characteristic ECG pattern on 12-lead

It’s all about the characteristic ECG pattern (if you’re lucky enough to get one). There are 3 variants:

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The Saddle-back type is easy to remember – “cowboy Arrhythmia”.

You also need to have 1 of:

  • Documented ventricular fibrillation (VF) or polymorphic ventricular tachycardia (VT).
  • Family history of sudden cardiac death at <45 years old .
  • Coved-type ECGs in family members.
  • Inducibility of VT with programmed electrical stimulation .
  • Syncope.
  • Nocturnal atonal respiration (abnormal pattern of breathing and brainstem reflex characterized by gasping, labored breathing, accompanied by strange vocalizations and myoclonus).

There are various genetic variations:

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Courtesy of Wikipedia!

Essentially, you need an ICD! Quinidine has been proposed as an alternative, but there is slim evidence based on case series only.

Undiagnosed, Brugada syndrome has been estimated to have a mortality of 10%, as in the sad cases above.

Pathophysiology

Gene mutations are found in 20%. Those genes encode for a sodium ion channel in the cell membranes of the myocytes. There is then disruption of the sodium channel’s ability to bind properly to ankyrin-G, an important protein mediating interaction between ion channels and cytoskeletal elements.

Mutation of the gene named SCN5A leads to a loss of the action potential dome of some epicardial areas of the right ventricle. This results in transmural and epicardial dispersion of repolarization. The transmural dispersion underlies ST-segment elevation and the development of a vulnerable window across the ventricular wall, whereas the epicardial dispersion of repolarization facilitates the development of phase 2 re-entry. This generates the extrasystole that  then fires off via an exposed part of the depolarisation circuit precipitating the often fatal ventricular tachycardia and/or ventricular fibrillation. All reported PM’s on patients who have died show a structural right ventricular pathology underlying the syndrome.

Other mutations:

Very recently a mutation in a second gene, Glycerol-3-phosphate dehydrogenase 1-like gene (GPD1L) has been shown to result in Brugada syndrome in a large multigenerational family (London, 2006). This gene acts as an ion channel modulator in the heart, although the exact mechanism is not yet understood.

Why athletes…and exercise must be bad?!

Well, the answer lies in the level to which these people stress their myocardium daily…to supra-physiological levels!  SO if they carry the defective gene(s), they are self selecting to present above those who are more sedentary. One of my personal heroes seen here pushing himself over and beyond…an example of what I mean!

I am exercise mad, as many Type A anaesthetists / EM physicians / Intensivists are. Should I worry? Some say we have a limited number of heart beats in our lifetime!!? Not sure I believe that one.

You can download our presentation on the subject here

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Also see

Dr Smith’s take on it

J Brugada’s take on it in 2009

Therapy for Brugada syndrome – Fish et al.

Blog from New Jersey about sudden death in athletes

My advice…don’t chuck out your trainers just yet. Death from lack of exercise, obesity and diabetes is probably the worst option!

JW