Cardioverter defibrillators (ICD or AICD)
An implantable cardioverter defibrillator (ICD) - or automatic implantable cardioverter defibrillator (AICD) - is used to monitor and treat patients with malignant tachyarrhythmia (e.g. ventricular fibrillation), providing protection against sudden cardiac death.
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What is an implantable cardioverter defibrillator?
Ventricular fibrillation is one of the most dangerous types of cardiac arrhythmia. When it occurs, a defibrillator can save a patient's life by delivering a strong electric shock to the heart. This results in all the cells of the heart muscle being stimulated at the same time, and allows normal sinus rhythm to be restored. Patients at a high risk of ventricular fibrillation or other malignant cardiac arrhythmias can now be fitted with miniature defibrillators (ICDs), with the process of implantation similar to that of a pacemaker.
The origins of implantable cardioverter defibrillators
On 4 February 1980, the first successful implantation of an automatic defibrillator was carried out at the Johns Hopkins Hospital in Baltimore by American cardiologist Michel Mirowski. Following this event, the automatic implantable defibrillator - and later the automatic implantable cardioverter defibrillator (ICD) - became one of the most successful therapeutic devices used within the field of cardiology.
What conditions can be treated using an implantable cardioverter defibrillator?
- Primary ventricular fibrillation
- Ventricular tachycardia
- Heart failure with decreased ventricular function (LVEF ≤ 35%)
What can an implantable cardioverter defibrillator accomplish?
The use of defibrillators is recommended primarily in patients with heart failure, in order to prevent sudden cardiac death as a result of dangerously fast tachyarrhythmias (LVEF ≤ 35%). The implantation procedure is similar to that used with pacemakers. Defibrillators continuously monitor the patient's heart rate and, if necessary, are able to terminate an episode of tachyarrhythmia (a dangerously fast and irregular heart rate) by either delivering quick electrical impulses that stimulate the heart muscle (known as fast pacing or antitachycardia pacing) or by delivering an electric shock. Many defibrillators can also measure and record additional parameters, such as patient-activated recordings, other types of arrhythmias, intrathoracic impedance (resistance) through the lungs and, where appropriate, details of any action taken by the device. Combined with home monitoring (remote monitoring), this can help to improve the patient's cardiac rhythm management. The effectiveness of individualized cardiac rhythm management depends on the quality of individualized programming and device management, which can help to ensure that potential problems are detected early and addressed without delay.
Treatment step-by-step
- Assessment with regard to patient's suitability for treatment with an implantable device and selection of the type of implantable pacing device to be used in line with the patient's requirements; information and consent procedure, including discussion with the patient and written consent.
- Implantation of the ICD under local anesthesia.
- The device's main lead is positioned in the tip of the right ventricle, in direct contact with the heart muscle.
- An alternative approach to implantation has recently become available for cases where the patient's anatomy or scar tissue from a previous surgical procedure prevents the lead from being advanced into the right ventricle. In these cases, a subcutaneous ICD can be used, which is implanted in a subcutaneous pocket (under the skin) and can deliver an electric shock to defibrillate the heart without the need for a lead to be implanted into the ventricle.
Follow-up treatment
- Management and programming of the device prior to discharge; consultation with the patient; outpatient appointment scheduled for follow-up.
- Regular follow-up appointments either with the outpatient department or a local specialist; home (remote) monitoring where appropriate.
Treatment results
At the Brandenburg Heart Center, the implantation of cardiac pacing devices forms an integral part of our approach to the treatment of cardiac arrhythmias. Every year, we implant approximately 100 single and dual chamber ICD systems - which have one and two leads, respectively - and approximately 100 biventricular ICD devices, which have three leads (cardiac resynchronization therapy with ICD).
Where can I find out more about ICD devices?
Deutsche Gesellschaft für Kardiologie (German Cardiac Society)
dgk.org
Deutsche Herzstiftung e.V. (German Heart Foundation)
herzstiftung.de
Defibrillator Deutschland e.V. [ICD self-help group]
defibrillator-deutschland.de