An implantable cardioverter defibrillator (ICD) insertion is the implantation of an electronic device just below the collarbone used to help regulate electrical problems with the heart. An ICD monitors the heart's electrical activity using wires with electrodes on the end that are placed in specific areas of the heart. The ICD responds to irregular rhythms with either anti-tachycardia pacing (ATP) consisting of low energy impulses to promote a normal heartbeat, or shock therapy with high energy impulses to prevent sudden cardiac arrest. An ICD can record and store information about your heart rhythm and therapies delivered by the ICD for your doctor to review.
The heart is basically a pump made up of muscle tissue that is stimulated by electrical currents, which normally follow a specific circuit within the heart.
This normal electrical circuit begins in the sinus or sinoatrial (SA) node, which is a small mass of specialized tissue located in the right atrium (upper chamber) of the heart. The SA node generates an electrical stimulus at 60 to 100 times per minute (in adults) under normal conditions; this electrical impulse from the SA node starts the heartbeat.
The electrical impulse travels from the SA node to the atrioventricular (AV) node in the bottom of the right atrium. From there the impulse continues down an electrical conduction pathway called the "His-Purkinje" system into the ventricles (lower chambers) of the heart. When the electrical stimulus occurs it causes the muscle to contract and pump blood to the rest of the body. This process of electrical stimulation followed by muscle contraction is what makes the heart beat.
An ICD may be needed when the electrical stimulation becomes chaotic and randomly starts in the ventricles instead of in the SA node in the right atrium. A variety of common cardiac conditions such as heart attacks and heart failure can lead to this type of electrical malfunction in the heart.
An implantable cardioverter defibrillator (ICD) is a small, electronic device that continuously monitors the electrical activity of the heart. It is about the size of a stop watch and is usually inserted under the skin in the upper chest. It consists of a pulse generator and wires, called leads. The pulse generator contains the battery and a tiny computer. One or more lead wires connect the pulse generator to specific locations in the heart. Although an ICD is a small device, it has many life-saving functions. Four key functions are anti-tachycardia pacing (ATP), cardioversion (light shock), defibrillation (stronger shock), and backup pacing.
ATP involves rapid regular pacing impulses delivered in order to correct and restore normal rhythm by overtaking a fast irregular rhythm. Most people are unaware when this therapy is being delivered.
Cardioversion (light shock) impulses are the next level of therapy. This light shock can generally be felt but not strongly.
Defibrillation, which is described by many as feeling like a "kick in the chest," is the strongest therapy that an ICD can be programmed to deliver.
The ICD can also be programmed to function as a basic pacemaker as needed. Sometimes after a shock is delivered, the heart may beat too slowly. The ICD has a "back-up" pacemaker, which can stimulate the heart to beat faster until the normal heart rhythm returns. Additionally, an ICD can act as a pacemaker not only after a shock is delivered, but also any time the heart rate drops below a preprogrammed rate.
These therapies (ATP, cardioversion, defibrillation, and basic pacing) are programmed by your doctor. Generally, when an irregular heart rhythm is detected, the mildest form of treatment (ATP) is delivered first, and then additional treatments (cardioversion or defibrillation) are added if the others do not restore the normal heart rhythm. Your doctor will program your ICD to your specific needs.
Persons with severe heart failure may benefit from cardiac resynchronization therapy, or CRT. A biventricular pacemaker is the device that is implanted to provide this therapy, which synchronizes the pumping of the right and left lower chambers (ventricles) of the heart. Individuals who benefit from CRT may also be at risk for sudden cardiac arrest, so a combination biventricular pacemaker and defibrillator may be implanted and programmed to provide any of the four therapies (ATP, cardioversion, defibrillation, and basic pacing) described above. Your doctor will decide which programming is most appropriate for you.
Other related procedures that may be used to assess the heart include resting and exercise electrocardiogram (ECG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest X-ray, computed tomography (CT scan) of the chest, echocardiography, electrophysiology studies, magnetic resonance imaging (MRI) of the heart, myocardial perfusion scans, radionuclide angiography, and cardiac CT scan. Please see these procedures for additional information.
Although MRI is a safe procedure, and in some hospitals increasingly performed prior to ICD placement (to evaluate for scar tissue after a heart attack or to precisely determine the course of a blood vessel), MRI is generally contraindicated after placement of an ICD or pacemaker, since the magenetic fields of the MRI scanner may interfere with device function. Always consult your cardiologist before agreeing to undergo an MRI if you have a pacemaker or ICD.
An ICD may be inserted in survivors of sudden cardiac arrest, syncope (fainting) due to ventricular arrhythmia, or some inherited heart conditions.
Some other reasons for implanting an ICD include, but are not limited to, the following:
There may be other reasons for your doctor to recommend an ICD insertion.
Possible risks of ICD insertion include, but are not limited to, the following:
If you are pregnant or suspect that you may be pregnant, you should notify your health care provider. If you are breastfeeding, you should notify your health care provider.
Patients who are allergic to or sensitive to medications or latex should notify their doctor.
For some patients, having to lie still on the procedure table for the length of the procedure may cause some discomfort or pain.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
An implanted cardioverter defibrillator insertion may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.
Generally, an ICD insertion follows this process:
After the procedure, you may be taken to the recovery room for observation or returned to your hospital room. A nurse will monitor your vital signs.
You should immediately inform your nurse if you feel any chest pain or tightness, or any other pain at the incision site.
After the period of bed rest has been completed, you may get out of bed with assistance. The nurse will assist you the first time you get up, and will check your blood pressure while you are lying in bed, sitting, and standing. You should move slowly when getting up from the bed to avoid any dizziness from the period of bedrest.
You will be able to eat or drink once you are completely awake.
The insertion site may be sore or painful, and pain medication may be administered if needed.
Your doctor will visit with you in your room while you are recovering. The doctor will give you specific instructions and answer any questions you may have.
Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room or discharged to home.
If the procedure is performed on an outpatient basis, you may be allowed to leave after you have completed the recovery process. However, it is common to spend at least one night in the hospital after ICD implantation for observation.
You should arrange to have someone drive you home from the hospital following your procedure.
You should be able to return to your daily routine within a few days. Your doctor will tell you if you need to take more time in returning to your normal activities. In addition, you should avoid lifting or pulling on anything for a few weeks. You may be instructed to limit movement of the arm on the side that the ICD was placed, based on your doctor's preferences.
You will most likely be able to resume your usual diet, unless your doctor instructs you differently.
It will be important to keep the insertion site clean and dry. You will be given instructions about bathing and showering.
Your doctor will give you specific instructions about driving. You will not be able to drive until your doctor gives you approval. These limitations will be explained to you, if they are applicable to your situation.
You will be given specific instructions about what to do the first time your ICD delivers a shock. For example, you may be instructed to dial 911 or go to the nearest emergency room in the event of a shock from the ICD. Calming yourself with slow deep breaths can be helpful if you are anxious after a shock.
Ask your doctor when you will be able to return to work. The nature of your occupation, your overall health status, and your progress will determine how soon you may return to work.
After implantation, your ICD will require regular evaluation or interrogation to evaluate its function and battery status, and assess for any significant events stored by the device. Your doctor will provide details regarding recommended frequency and mode of evaluation.
Notify your doctor to report any of the following:
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.
The following precautions should always be considered. Discuss the following in detail with your doctor, or call the company that made your device:
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