A 48-year-old woman with Romano-Ward syndrome (a hereditary long QT syndrome), asthma and an automatic implantable cardioverter defibrillator presented for laser surgery for debulking of a massive nasopharyngeal tumour prior to radiotherapy. Automatic implantable cardioverter defibrillators have only relatively recently been used to treat patients with the long QT syndrome and are indicated for the high-risk individual when conventional treatment has failed or when beta-blockers are contraindicated. If surgery requires the use of surgical diathermy, a cardiac technician must be present to deactivate the defibrillator and external pacing electrodes are sited on the chest until the defibrillator can be reactivated. Radiotherapy requires both deactivation and shielding of the device.