The risk of arrhythmias can be reduced in several ways. Medications that further prolong the QT interval such as sotalol should be avoided, as should very strenuous or competitive exercise. Blood potassium levels should be kept within the normal<unk> . Potassium supplements may be used at times when potassium is being lost such as when experiencing diarrhoea or vomiting, but medications that encourage the retention of potassium such as spironolactone or amiloride may also be required. Beta blockers such as propranolol or nadolol reduce the risk of arrhythmias. An implantable defibrillator, a small device that monitors the heart rhythm and can automatically deliver an electric shock to restart the heart, may be used. These devices are recommended for those with<unk>  who have experienced a cardiac arrest or a blackout whilst taking beta blockers. Due to the higher risk of arrhythmias associated with<unk>  than other forms of long QT syndrome, a defibrillator may be considered even in those without any symptoms. In those who experience recurrent arrhythmias despite medical therapy, a surgical procedure called sympathetic denervation can be used to interrupt the nerves that stimulate the heart.
Jervell and Lange-Nielsen syndrome
Long QT syndrome
Fox–Fordyce disease
Andersen–Tawil syndrome
Laron syndrome
Cowden syndrome
Koolen–De Vries syndrome
Prader–Willi syndrome