The first component or generator contains a computer chip or circuitry with RAM (memory), programmable software, a capacitor and a battery; this is implanted typically under the skin in the left upper chest.

Recent developments include the subcutaneous ICD (S-ICD) which is placed entirely under the skin, leaving the vessels and heart untouched.

Special care should be taken not to put excessive strain on the shoulder, arm and torso area where the ICD is implanted.

Particularly to be avoided are exercises that cause the clavicle to be pulled down towards the ribs, such as lifting weights with the arm, on the ICD site, while standing.

[citation needed] Implantable cardioverter defibrillators have demonstrated clear life-saving benefits, while concerns about patient acceptance and psychological adjustment to the ICD have been the focus of much research.

[13] Researchers, including those from the field of cardiac psychology, have concluded that the quality of life (QoL) of ICD patients is at least equal to, or better than, that of those taking anti-arrhythmic medications.

[19] Problems in psychosocial adjustment to ICDs, including the experience of anxiety, among spouses or other romantic partners are also prevalent.

[22] Recent advances include app integration for home interrogation and remote care has been correlated with some mortality benefit.

[23] Implantation of ICD is meant to prevent sudden cardiac death and is indicated under various conditions.

Some of the Class I indications are as follows:[24] A number of clinical trials have demonstrated the superiority of the ICD over AAD (antiarrhythmic drugs) in the prevention of death from malignant arrhythmias.

[26] In 2002 the MADITII trial showed benefit of ICD treatment in patients after myocardial infarction with reduced left ventricular function (EF<30).

Most ICDs nowadays are implanted transvenously with the devices placed in the left pectoral region similar to pacemakers.

A recent study by Birnie and colleagues at the University of Ottawa Heart Institute has demonstrated that ICDs are underused in both the United States and Canada.

[27] An accompanying editorial by Simpson of Queen's University explores some of the economic, geographic, social and political reasons for this.

[28] The development of the ICD was pioneered at Sinai Hospital in Baltimore by a team including Michel Mirowski, Morton Mower, Alois Langer, William Staewen, and Joseph "Jack" Lattuca.

In 1972 Bernard Lown, the inventor of the external defibrillator, and Paul Axelrod stated in the journal Circulation – "The very rare patient who has frequent bouts of ventricular fibrillation is best treated in a coronary care unit and is better served by an effective anti-arrhythmic program or surgical correction of inadequate coronary blood flow or ventricular malfunction.

In fact, the implanted defibrillator system represents an imperfect solution in search of a plausible and practical application.

Despite the lack of financial backing and grants, they persisted and the first device was implanted in February 1980 at Johns Hopkins Hospital by Dr. Levi Watkins Jr.[29][32] The first devices required the chest to be cut open and a mesh electrode sewn onto the heart; the pulse generator was placed in the abdomen.

The integration of these various parameters is very complex, and clinically, the occurrence of inappropriate therapy is still occasionally seen and a challenge for future software advancements.