Implantable Cardioverter-Defibrillator (ICD)
What is an ICD?
An ICD is a device, about the size of a deck of cards, which is implanted under the skin and has wires (leads) that pass into the heart. The main purpose of the ICD is to monitor the heart for the life-threatening rhythms ventricular tachycardia (VT) and ventricular fibrillation (VF) that can lead to cardiac arrest and death. The ICD can terminate the abnormal rhythm and restore normal rhythm by delivering a powerful shock to the heart muscle or through a special type of cardiac pacing.
The ICD also has all the functions of a pacemaker and can send very small electrical impulses to the heart to stimulate contraction of the heart. This function keeps the heart from going to slow in patients where this is a problem.
What are the indications for the procedure?
Sudden cardiac arrest from VF and VT is a common cause of death among patients whose heart muscle is weak. When the ejection fraction (defined below*) is below 35% the risk of lethal arrhythmia rises. Most patients with a heart that has been weakened by causes not considered immediately reversible (such as prior heart attacks and viral illnesses) are at higher risk of VT and VF and should be considered candidates to receive an ICD.
How is it done?
When we’re ready to start you’ll be brought into the cardiac catheterization lab (much like an operating room with x-ray cameras) and you’ll lie on a table while our technicians prepare the area on your body where we’ll be working. In most patients we place the ICD just below the collarbone on the left chest wall. We can also implant the ICD on the right if there is a reason the left side can’t be used (e.g. a patient with a left arm dialysis fistula or previous surgery for breast cancer). The technicians will cover your chest and face with a drape to protect the sterile area where we’ll work (the drape over the face can bother some patients—we can provide more sedation to you if you think this will be a problem). After providing you with some sedating medication we numb the area of skin with local anesthetic.
We make an incision about two inches long and then create an area under the skin where we can place the ICD. We pass the wires (leads) into veins that lead directly into the right atrium and ventricle of the heart. Once we place and secure the leads in the heart we test them electrically to make sure we have good conduction and adequate position to pace the heart. We attach the leads to the ICD and place it under the skin. At that point you will be fully sedated and we will test the shock function of the ICD. Finally, we close the skin with absorbable suture so that you will not need stitches removed. You will stay in the hospital overnight so that we can observe your heart rhythm and check the status of your ICD and leads in the morning. There is a small chance that one of the leads will pull free from where we put it within the first few hours after surgery. We are able to easily detect this on the morning after surgery and return to the cath lab to fix it if necessary.
If all goes well you are discharged from the hospital on the day after surgery.
How do you prepare for the procedure?
ICD insertion is done on both hospitalized and ambulatory patients. As an outpatient having this done electively you will first visit with the cardiologist in the office to go over the procedure and discuss the risks and alternatives. Since you will be asked to sign document of consent be sure to ask any question and raise any concern you may have. You will need to have basic blood work done and this can be drawn in the office.
Unless instructed otherwise you should be fasting on the morning of the procedure. In general we want you to take your usual morning medications with the exception of any we’ve told you not to take (please talk to our nurses or schedulers if you have any questions about this).
We do this procedure in the hospital at Midlands, Bergan, Mercy, Immanuel and Lakeside and you’ll receive specific instructions on where to show up and what time to be there.
What are the risks of the procedure?
The risk of bleeding and bruising accompanies any invasive procedure. The risk of infection of the ICD site is about 1-4% nationally. Because the vein we use to gain access to the heart lies very near the lung there is the possibility of puncturing and collapsing the lung, necessitating the placement of a chest tube. Leads have been known to perforate the muscle in the heart and cause potentially life-threatening bleeding around the heart.
These complications are uncommon and we can take measures to treat them when they arise. We take all these potential complications very seriously and take great precautions to avoid them.
* Ejection Fraction: We quantify the strength of the left ventricle (the main pumping chamber) by referring to the heart’s ejection fraction, a measure of the percentage of blood squeezed out of the heart with each beat. The left ventricle doesn’t wring every drop out with each beat, but rather pushes out about two thirds of its full volume. This number is the ejection fraction. The normal ejection fraction is between 55 and 75%.