Subcutaneous implantable defibrillator

A type of implantable defibrillator placed under the skin

A subcutaneous implantable defibrillator (S-ICD) is a type of implantable cardioverter-defibrillator (ICD) that is designed to provide defibrillation therapy for patients at risk of sudden cardiac arrest. Unlike traditional ICDs, which have leads that are placed inside the heart, the S-ICD has leads that are placed under the skin, outside the ribcage.

Design and Function

A subcutaneous implantable defibrillator device

The S-ICD system consists of a pulse generator and an electrode that are implanted subcutaneously. The pulse generator is typically placed on the left side of the chest, and the electrode is positioned along the left side of the sternum. This configuration allows the device to detect and treat life-threatening arrhythmias without the need for transvenous leads.

The S-ICD continuously monitors the heart's rhythm and delivers a shock if a dangerous arrhythmia, such as ventricular fibrillation or ventricular tachycardia, is detected. The device is programmed to recognize and treat these arrhythmias while minimizing inappropriate shocks.

Advantages

The primary advantage of the S-ICD over traditional ICDs is the elimination of transvenous leads, which are associated with complications such as lead fracture, infection, and thrombosis. By avoiding the vascular system, the S-ICD reduces the risk of these complications and is particularly beneficial for patients with limited venous access or those at high risk of infection.

Indications

The S-ICD is indicated for patients who require defibrillation therapy but do not need pacing for bradycardia or antitachycardia pacing. It is suitable for patients with a history of ventricular arrhythmias or those with a high risk of sudden cardiac arrest due to conditions such as hypertrophic cardiomyopathy or long QT syndrome.

Limitations

While the S-ICD offers several advantages, it also has limitations. It does not provide pacing support, which is necessary for some patients with bradyarrhythmias. Additionally, the device may be less effective in patients with certain anatomical variations or those who require cardiac resynchronization therapy.

Procedure

The implantation of an S-ICD is a minimally invasive procedure typically performed under general anesthesia. The device is implanted through small incisions, and the electrode is tunneled subcutaneously. The procedure usually takes about one to two hours, and patients can often return home the same day or the following day.

Follow-up and Monitoring

After implantation, patients require regular follow-up to monitor the function of the S-ICD and to adjust the device settings as needed. Follow-up visits typically include device interrogation and assessment of the patient's clinical status.

Related pages

• Implantable cardioverter-defibrillator
• Sudden cardiac arrest
• Ventricular fibrillation
• Hypertrophic cardiomyopathy