Brugada syndrome

Brugada syndrome is an inherited quirk of the heart's electrical system. The muscle itself is healthy: on a scan the walls, the valves and the pumping all look ordinary, and a person can go years without a single complaint. The fault sits in the proteins that form channels for sodium to enter heart cells, and those channels decide how evenly an electrical impulse travels through the heart. The first sign of trouble can be a sudden blackout or a cardiac arrest — most often at night, during sleep, in a man of about forty. The condition is rare, but once recognised it can be managed, and unrecognised it cannot.

What actually goes wrong in the heart

The sodium current is what fires a cell into action. When there are fewer channels than there should be, or they open sluggishly, the cells of the right ventricle recover out of step with each other, by fractions of a second. That is enough for an impulse to start circling and to trigger ventricular fibrillation: a chaotic quiver during which blood stops moving.

The disturbance is concentrated in the right ventricular outflow tract, a small area beneath the pulmonary artery. That is why the trace only shows it in the right chest leads, where the ST segment lifts into a characteristic coved shape. It is that pattern, rather than symptoms or imaging, that the diagnosis rests on.

The trait is usually passed on in a dominant fashion: a child of someone with the syndrome has roughly a one in two chance of inheriting the same fault. The SCN5A gene, which codes for the sodium channel, is found in about a fifth of those tested; in the rest the responsible fault is still unknown, and that does not undo the diagnosis.

How it shows itself

Usually it does not: the syndrome turns up by accident, on a tracing taken before surgery or at a check-up. Where there are signs, they look like this:

• fainting with no warning — there is no time to feel light-headed and sit down, consciousness switches off at once, typically at rest, at night, after a heavy meal or during a fever;
• slow, gasping breathing during sleep that the people nearby notice; this is no longer snoring but the sound of a rhythm that has broken down;
• convulsive attacks treated for years as epilepsy, because nobody looked for the real cause: a brief halt in blood flow to the brain;
• palpitations and skipped beats, thumping in the chest at night;
• cardiac arrest as the first and only event.

First events usually fall between the ages of thirty and fifty, though in children a high fever can set one off. Men are affected several times more often than women carrying the same inheritance. In South-East Asia the syndrome is considerably more common and has long been known there under local names for sudden death in sleep.

When minutes count

Call your emergency number straight away (112 across Europe) if:

• someone does not respond to your voice and is not breathing, or is taking occasional gasping breaths — this is cardiac arrest;
• someone is having a convulsive seizure;
• someone has collapsed and cannot be roused.

Until the ambulance arrives, start chest compressions and send somebody for an automated external defibrillator: they hang in stations, airports and shopping centres. The device reads the rhythm itself and says out loud what to do. Every minute without a shock costs roughly a tenth of the chances, so starting matters far more than doing it faultlessly.

What sets the rhythm off

Almost everything that pushes such a heart towards arrhythmia can be foreseen and removed.

Fever. The single biggest trigger. Heat changes how sodium channels behave, and the dangerous pattern can surface in someone whose resting trace is clean. The rule is simple: do not wait it out, bring the temperature down early with paracetamol at any infection. In children with this diagnosis fever is the usual route to an event, and the family should have a plan agreed with the doctor in advance.

Medicines. The dangerous ones block those same sodium channels: class I antiarrhythmics, some antidepressants and other psychiatric drugs, lithium, certain anti-sickness and antihistamine medicines, and several general and local anaesthetics. An international registry keeps and updates the list, and the doctor checks it before prescribing. Only one thing is asked of you: mention the diagnosis before the prescription, before an anaesthetic and before the dentist's injection, not afterwards.

Cocaine and stimulants — a direct and frequent cause of events in young people.

A large amount of alcohol at once: the danger lies in the single big session, not in the usual glass.

Heavy meals late at night. A full stomach strengthens the pull of the vagus nerve, and against that background the pattern becomes more pronounced. Hence the night-time events after a long dinner.

Loss of fluid and salts through vomiting, diarrhoea or work in the heat: potassium drops and the rhythm turns unstable.

Sport used to be banned outright; today the decision is made case by case, since the risk lies less in the effort itself than in overheating, dehydration and the first minutes of recovery afterwards.

How the diagnosis is made

The foundation is a twelve-lead tracing recorded in a particular way: the right chest electrodes are placed one or two rib spaces above their usual position. In those higher positions the pattern shows up far more often, and without that adjustment the diagnosis is frequently missed.

There are several pattern types, and only the first, with its coved elevation, counts as diagnostic; the others are suspicious and need confirming. Confirmation comes from a provocation test: a sodium channel blocker is given into a vein and the trace is watched for the characteristic picture. It is done only as an inpatient, under continuous monitoring, with a defibrillator standing ready. Genetic testing is most useful for relatives: once the fault is identified, they can be checked for exactly that one. A negative result rules nothing out.

There is a caveat patients are rarely told about. The very same pattern appears temporarily with a high blood potassium, in poisoning by those same sodium blockers or by antidepressants, in right ventricular ischaemia, in acute pericarditis, and sometimes simply at the peak of a fever in a person with no inherited fault at all. Such a trace disappears along with its cause and is not Brugada syndrome. This is why a lifelong label is never attached to one chance recording: it is repeated first, once the cause has been dealt with.

Who needs a defibrillator and who does not

No tablet repairs the channels. Treatment has a different aim: to stop a collapsing rhythm from ending in death.

An implantable cardioverter defibrillator is a small device under the skin that watches the rhythm and delivers a shock if fibrillation starts. It goes to people who have already survived a cardiac arrest, and to those who have had blackouts that look arrhythmic alongside a diagnostic pattern on the trace. Someone without symptoms whose pattern was found by chance usually does not need one: risk in that group is low, while inappropriate shocks and infection of the device pocket are a very real price. Those people are followed up and the decision is revisited if anything changes. Where pacing is not required, the subcutaneous model is chosen: its lead runs outside the veins, so vein and valve complications do not arise.

Quinidine is an old antiarrhythmic drug that markedly reduces the number of events in some people; it is used when the device is shocking often, in what is called an electrical storm, and when an implant is not possible. Another route is catheter work on that same outflow tract area from the outer surface of the heart, carried out in specialist centres when shocks keep recurring.

Why the whole family is checked

One person's diagnosis is a reason to check blood relatives of the first degree: parents, brothers and sisters, children. It starts with a tracing using the high leads and, where the mutation is known, adds targeted genetic testing.

A family history is a separate reason to get checked: an unexplained death of a young relative in their sleep, at the wheel for no visible reason, in the water when they were a strong swimmer, or put down to an epilepsy that was never confirmed. Such stories often turn out to be the only trace of an inherited arrhythmia.

In some carriers the resting tracing is entirely normal and changes only with a fever. That is not a reason to leave them uninformed: the rules about temperature and about medicines apply to them just the same.

Online consultation

In an online consultation the doctor goes through what the blackout looked like and what came before it, reviews the tracings and reports that already exist, and explains which leads to ask for and when a provocation test is worth discussing. The same appointment is the place to build a personal list of drugs to avoid, to set out a plan for feverish illnesses and to decide which relative should be checked first.

This material is for information only and does not replace medical advice.