What is an implantable defibrillator (ICD/AICD)?

Implantable defibrillators are also called in short as ICD and AICD, meaning implantable cardioverter defibrillator and automatic implantable cardioverter defibrillator. They are devices which are implanted under the skin and connected to the heart using leads introduced through the blood vessels. These devices continuously monitor the heart rhythm and automatically treat serious abnormal rhythms when needed.