page_title: Catecholaminergic polymorphic ventricular tachycardia
section_title: Implantable cardioverter-defibrillator
hierarchical_section_title: Catecholaminergic polymorphic ventricular tachycardia / Treatment / Implantable cardioverter-defibrillator
caption_attribution_description: English: Labelled chest X-ray showing an implantable cardioverter defibrillator (ICD) with atrial and ventricular leads
context_page_description: Catecholaminergic polymorphic ventricular tachycardia is an inherited genetic disorder that predisposes those affected to potentially life-threatening abnormal heart rhythms or arrhythmias. The arrhythmias seen in CPVT typically occur during exercise or at times of emotional stress, and classically take the form of bidirectional ventricular tachycardia or ventricular fibrillation. Those affected may be asymptomatic, but they may also experience blackouts or even sudden cardiac death.
  CPVT is caused by genetic mutations affecting proteins that regulate the concentrations of calcium within cardiac muscle cells. The most commonly identified gene is RYR2, which encodes a protein included in an ion channel known as the ryanodine receptor; this channel releases calcium from a cell's internal calcium store, the sarcoplasmic reticulum, during every heartbeat.
  CPVT is often diagnosed from an ECG recorded during an exercise tolerance test, but it may also be diagnosed with a genetic test. The condition is treated with medication including beta-adrenoceptor blockers or flecainide, or with surgical procedures including sympathetic denervation and implantation of a defibrillator.
context_section_description: While medication and sympathectomy aim to prevent abnormal heart rhythms from occurring in the first place, an implantable defibrillator (ICD) may be used to treat arrhythmias that medication has failed to prevent and restore a normal heart rhythm. These devices, usually implanted under the skin at the front of the chest below the shoulder, can continuously monitor the heart for abnormal heart rhythms. If a life-threatening arrhythmia is detected, the device can deliver a small electric shock to terminate the abnormal rhythm and restart the heart.
  Implantable defibrillators are often recommended for those with CPVT who have experienced blackouts, ventricular arrhythmias or cardiac arrest despite taking appropriate medication. These devices can be life-saving, although the resulting surge of adrenaline caused by the pain of an electric shock from the device can sometimes bring on a cycle of recurrent arrhythmias and shocks known as an electrical storm. Because of this, it is strongly recommended that those with an ICD implanted for CPVT take a beta blocker to dampen the effects of adrenaline.
caption: Chest x-ray of a patient with an implantable defibrillator (components labelled)
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