Brugada syndrome

The symptom of Brugada Syndrome is sudden death by heart failure - at any time, without warning. The heart failure happens as an arrhythmia or fibrillation - rapid, irregular, and ineffective heartbeat.

Heart-beat is controlled by electrical signals which are generated rhythmically in one part of the heart, and travel around it, triggering the chambers to contract in the correct order. In both muscles (of which the heart is one) and nerves, signals are conveyed by the decay of electrical fields, which have been created by the movement of minerals (particularly sodium, calcium, and potassium) across the cell membranes, creating a voltage difference between the inside and outside of the cell.

The charged mineral atoms (correctly called ions) are moved across cell membranes by protein complexes called ion-channels. These have the structure of tubes which cross the cell membrane, and they can allow, restrict, or actively move, ions of a particular element.

Brugada syndrome (at least sometimes) is associated with a disorder of sodium ion channels - they overly restrict the movement of sodium ions into the cell, interfering with the regulation of the electric field, and hence the electrical signalling.

There are a number of 'ion channelopathies' known, which can cause arrhythmic heart failure, either (apparently) spontaneously, or as a consequence of physical or emotional stress. Some of these involve potassium ion channels, others, calcium channels.

In some cases, the disease can be detected by observing characteristic patterns on an electrocardiograph, which may be present all the time, or might be elicited by strenuous exercise, or by the administration of particular drugs. Apart from the electrical characteristics, there are no other physical diagnostic features - so it is not detectable post mortem; one man with Brugada wrote*: "...the standard tests that I was given... revealed that my heart was actually in great shape, despite a youth spent smoking and eating fatty foods."

There are ethnic and sex differences in the incidence of ion channelopathies. All Italian children who play sport are routinely checked by electrocardiogram. Brugada syndrome, which is mostly seen in males, is believed to be second to traffic accidents as a cause of death to Thai men.

For a very few of the ion channelopathies, the causative genetic mutation is known, and so there is the possibility of DNA-based diagnosis.

There is, however, in most cases, no cure. Duncan Graham-Rowe (see references) discovered that he had Brugada syndrome after his otherwise healthy 26-year-old brother suddenly died. He now lives with an implanted defibrillator, which monitors his heart beat, and waits for the call to zap him back to life.

External links and references

• Graham-Rowe: "Death in the Family", New Scientist 20 Sept. 2002
• Algado et al: http://www.medspain.com/ant/n13_jun00/Brugada.htm
• Winstead: http://www.celera.com/genomics/news/articles/01_01/fatal_flaw.cfm
• Behr: http://www.c-r-y.org.uk/long_qt_syndrome.htm
• http://molecularmedicine.medscape.com/reuters/prof/2000/09/09.01/20000901scie006