What is an implantable cardioverter defibrillator (ICD)?
Implantable cardioverter defibrillator (ICD) is a cardiac implantable electronic device (CIED). The device is implanted in under the skin under local anaesthesia, below the left collar bone. The electrode lead from the device is introduced into the right sided chambers of the heart through a vein (blood vessel carrying deoxygenated blood to the heart) behind the left collar bone. The device senses the heart rhythm automatically. It can detect life threatening abnormalities in the heart rhythm and treat them electrically. If a certain abnormal rhythm from the lower chambers of the heart known as ventricular tachycardia is detected, the ICD tries to overdrive it by fast pacing (giving regular electrical pulses to the heart). If it does not suppress the ventricular tachycardia, the ICD delivers a shock through its high voltage coil within the heart. The X-ray picture shown above depicts a high voltage coil in the superior vena cava – blood vessel carrying deoxygenated blood from upper part of the body to the heart. There is another coil in the right ventricle (lower muscular chamber of the heart), which is not visible in the picture because of the thickness of the heart muscle over it.
If a life threatening rhythm from the lower chambers of the heart (ventricular fibrillation) is detected by the ICD, it immediately gives a shock to correct the rhythm. Thus the ICD is an important life saving device which safeguards the recipient from sudden death by dangerous abnormal electrical rhythms of the heart.