ICD Implantation

Implantable Cardioverter Defibrillator has mainly 2 components -

Pocket sized generator which has a battery and the software to detect abnormal heart rhythms and subsequently give electric shocks to negate them. This is basically kept under the skin below the patient's collar bone.

 

Leads which are connected at one end to the battery and traverse in the veins of the body to reach the heart chambers. Depending on the different types, there may be single, two or three leads in the ICD.

• Conventional ICD - these as explained above are placed under the collar bone with the leads traversing inside the heart chambers. Inherently these ICD have an additional pacemaker function as well. Depending on the number of leads they may be -

Single chamber ICD - the single lead is placed in the right lower chamber of heart (right ventricle).

Dual chamber ICD - the two leads are placed in the right upper and lower chambers of the heart (right atria and ventricle).

 

• CRTD - this combines functions of both CRT and ICD, i.e. gives electric shocks to the heart when needed and also helps in augmenting the pumping capacity of the heart.
• Subcutaneous ICD - this device is placed in the tissue of the body, usually the left side of the breast bone, rather than inside the heart. Thus this does not have a pacemaker function. Advantage of this is that it has less chances of infections and is usually preferred in young patients.

 

Recent technological advancements in ICD is that now they are also MRI compatible and their battery life has also improved, thus battery replacement needs to be done at longer intervals.

Prior to implanting an ICD, all possible investigations should be done to justify inserting this device.

• Depending on the patient and his inherent heart conditions, ECG, holter monitoring or loop monitoring (prolonged heart rhythm monitoring) should be done to recognize the abnormal heart rhythm.
• Echocardiogram is also mandatory to identify the heart functioning prior to ICD consideration.
• In some cases cardiac MRI may be beneficial to identify scars or identify certain genetic disorders.
• In some cases electrophysiology studies may also be needed to correctly identify the abnormal heart rhythms.

 

Importance of Consultation with Cardiologists and Electrophysiologists

It is a big decision whether to implant the ICD or not. Thus a thorough understanding of the heart condition and the pros and cons of the procedure is needed prior to going ahead with it.

Usually patients are admitted a day prior or on the day of the procedure. Fasting for around 6 hours is recommended prior to the procedure. Routine blood checks are necessary prior to the procedure.

 

Step-by-Step Guide to ICD Implantation Procedure

• Patients are usually awake during the procedure.
• Local anaesthetic is given under the collar bone, usually the left side where a pocket is created to place the battery.
• Through the same place the vein under the collar bone is cannulated to insert the leads which are placed in the heart chambers under fluoroscopy.
• Thereafter the skin is closed with sutures or staplers and the patient is shifted to the ICU.

 

Recovery and Post-procedural Care

In the ICU patients are observed overnight for abnormal heart rhythms and to look for signs of shortness of breath to rule out any injury to the heart or lungs secondary to the procedure. Once stable, patients are usually discharged in one to two days.

Early complications -

• Infection at the pocket site or on the leads inserted. To treat this usually a course of prolonged antibiotics is needed.
• Heart injury due to lead insertion is occasionally observed in the form of fluid around the heart (pericardial effusion). This may be life threatening and may need removal of this fluid or a surgeon may be needed to repair the damage made in the heart due to the lead implantation.
• Lung injury due to a puncture site below the collar bone in the form of pneumothorax (air under the lungs). This may need draining of air from the lung space, if causing difficulty in breathing.
• Subcutaneous emphysema (air under the skin) is sometimes also seen. It is usually managed conservatively and only surgeons are called in occasionally to relieve the same.
• Lead displacement can happen in the early weeks of the procedure. To prevent or minimise the chances of it, we ask the patient not to elevate the arm above the shoulders for a month or so.

Late complications -

• Infection on the leads due to some secondary infection in the blood leading to infective endocarditis. This may need lead extraction to take the infective source out of the body along with a prolonged course of antibiotics.
• Battery depletion - this is not a complication, but once the battery runs out, it needs a redo procedure to replace the battery. The leads are not changed and just the old battery is taken out and replaced with a new one.
• Inadequate firing of the ICD - sometimes an abnormal rhythm may be falsely detected, which may trigger generation of electric shock, when ideally it would not be needed. This leads to faster depletion of the battery, but more importantly it is emotionally and physically traumatic to the patient as the delivery of electric shocks, though lasting only a few seconds are painful.

Arm care on the side of ICD insertion is needed to prevent displacement of the leads. Usually it is recommended to avoid lifting heavy weights and also to lift the arm over the shoulders. Various countries have different rules in terms of driving post ICD insertion. It depends on the inherent heart condition as well. Thus it is imperative to ask the cardiologist implanting your device as to when it would be possible to get back to routine activities, including driving your car.

 

Monitoring and Maintenance of the ICD

Lifelong vigilance of the ICD device is necessary. It may need modifying the setting in the ICD by the cardiologist implanting the device as per the readings on regular ICD checks.

 

Benefits of ICD Implantation

This procedure, if done in the correct patient, helps with longevity of the patient and can prevent sudden cardiac deaths.