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Treatment and advice If you have PCCD you will need to have a pacemaker fitted in order to stop dangerous bradycardia from occurring. This may not prevent tachycardias from occurring, so you may also need to take antiarrhythmic drugs. Some people may need to have an ICD fitted instead of a pacemaker. (For more on pacemakers see page 43, and for more on ICDs see page 41.) Medication alone does not help.

Short QT syndrome (SQTS) This rare condition is similar to but distinct from LQTS. As the name suggests, the QT interval in carriers is shorter than in normal people. This means that the heart takes a shorter time to repolarise or reset itself, making it prone to ventricular arrhythmias. There is also an increased risk of a less dangerous arrhythmia from the top chambers of the heart (the atria) called atrial fibrillation. This is an irregular and rapid heart rhythm that may go unnoticed or causes breathlessness and palpitations. As in LQTS, potassium channel genes are affected, but instead of allowing less potassium through they allow through too much too quickly.

What are the symptoms? Palpitations, blackouts and cardiac arrest.

Are there any physical signs? There are no physical signs usually, except if there is atrial fibrillation when an irregular rapid pulse may be felt by the doctor.

How is it diagnosed? The ECG abnormalities are usually detected either on a standard ECG or a 24-hour Holter. An electrophysiological (EP) study may also help the doctor make a diagnosis. (We describe all these tests on pages 26-33.) Genetic testing may find a potassium channel mutation in affected members of a family that may then also be found in other relatives.

Treatment and advice If you have SQTS it is likely that an ICD will need to be fitted in order to treat dangerous arrhythmias. Quinidine has been used in some patients but it is unclear whether it is safe to rely on medication alone. Tablets may also be used to treat atrial fibrillation.

Early repolarisation syndrome Idiopathic ventricular fibrillation (IVF) describes the group of conditions responsible for life-threatening, rapid rhythm disturbances without any signs of the heart diseases we have described above. In some of these patients changes on their ECG, known as early repolarisation, have been seen. This has become known as early

Cardiac Risk in the Young 12

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