Implantable Defibrillators
Sudden and dangerous heart rhythms can cause the heart to stop effectively pumping blood to the rest of the body, leading to a condition called cardiac arrest and potentially resulting in sudden cardiac death. An implantable cardioverter-defibrillator (ICD) constantly monitors the heart for these abnormal rhythms and delivers therapy to treat them if necessary.
The ICD system consists of two parts: a miniaturised computer, which is the ICD itself, and a battery sealed within a case. In addition, one to three insulated wires called leads connect the device to the heart.
It is important to note that an ICD can also function as a pacemaker, providing electrical stimulation to keep the heart beating at a normal rate if it is too slow.
Defibrillator Implantation
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When receiving an ICD, the device is typically implanted under your collarbone. Prior to the procedure, the area is thoroughly sterilised using antiseptic solution and allowed to dry. It's important that you keep your arm still and avoid contaminating the operating area. Sterile drapes will cover your face temporarily, but they will be removed shortly after.
To ensure your comfort during the procedure, an anaesthetist may be present. Alternatively, sedating medication may be given through a drip in some settings. Despite receiving medication, you will remain aware of your surroundings and able to communicate with your doctor. It's vital that you communicate any discomfort or concerns to your doctor, so they can adjust the medication dosage accordingly. Moreover, a mix of fast- and slow-acting local anaesthetics is used to numb the site, which will continue to work for several hours after the procedure.
The ICD wires are inserted into a vein that channels blood from the arm back to the heart. Using an x-ray called an image intensifier, the wires are threaded through the vein and into different areas of the heart. This part of the procedure may take a while, as your doctor will frequently test the wires to ensure they are in the optimal position to deliver energy to the heart. Once the wires are in place, the ICD is connected to the leads and implanted in a "pocket" under the skin, with the incision closed.
You may experience some pain after the local anaesthesia wears off, which should be manageable with paracetamol. If you need additional pain relief while in the hospital, please inform the nursing staff. The duration of the procedure varies depending on several factors, but it may take several hours.
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Following the pacemaker implantation procedure, you will see some dressings over the groin area. In some cases, a long suture may be visible, but it will be removed after a brief period.
After the procedure, a chest x-ray will be taken to ensure the pacemaker is correctly placed. The device will also be checked using a special computer called a programmer, which allows adjustments to be made to suit your individual requirements. If everything is in order and you are feeling well, you will be discharged home on a short course of antibiotics.
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For the safety and well-being of patients, preventing infection during ICD implantations is of utmost importance. The utmost care is taken during the procedure to prevent this complication. However, it's essential that patients monitor their wound daily for any signs of infection, including fever, redness, heat, increased swelling, or new drainage. If you experience any of these symptoms, please report them to Dr. Hsieh immediately. Please refrain from tampering with the operating site yourself.
For the first two weeks after the procedure, it's important to avoid using the arm for strenuous activity and refrain from raising the arm on the side of the device above shoulder level for 4-6 weeks. This allows time for the lead(s) to attach firmly to the heart tissue and for the incision to heal properly. It's also important to avoid bumping or hitting the area around the implant, so contact sports are not recommended. However, you are encouraged to use the arm for light activities to prevent developing a frozen shoulder.
On the topic of driving with an ICD, it's important to note that commercial licences are not permitted by the Roads and Traffic Authority except under exceptional circumstances. For private vehicles, holding an unconditional licence is no longer possible, but a conditional licence can be obtained with regular medical review. If a cardiac arrest has occurred, driving is not permitted for six months. For a preventative ICD, driving should be avoided for two weeks if there were no symptoms such as dizziness, and four weeks if there were. Additionally, after a routine generator change, driving should be avoided for two weeks.
ICD checkups are necessary at two weeks and every few months thereafter. However, if you experience any unusual symptoms, such as difficulty breathing, dizziness, fainting, chest pain, hiccupping, or signs of infection, please report them to Dr. Hsieh.
After the implantation, you will receive a Medical Device ID card from the ICD company, which you should keep with you to alert medical and security personnel that you have an implanted device. Please note that the metal components of the device may set off airport security metal detector alarms and that airport security wands can temporarily affect the device. If security personnel use a handheld wand, ask them to perform the search quickly and avoid holding the wand over the device. If you have any doubts about equipment to avoid, please speak to your doctor or the device manufacturer for guidance. Most manufacturers have engineers who can determine whether the electrical field generated by a piece of equipment can interfere with the ICD.
While mobile phones can potentially interfere with the proper operation of the device, simple precautions, such as not carrying the phone directly over the ICD and holding it up to the ear that is farthest from the ICD, can minimise the risk.
In the event that your ICD delivers a shock, you will likely feel it. It is important to find a safe place to sit and catch your breath. After a few moments, your heart should return to a normal rhythm. You may feel a bit lightheaded or disoriented for a short period of time. Please let your doctor know, and you may be asked to come into the office or be admitted into hospital. The data from your heart's activity will be reviewed, and your treatment plan may be adjusted accordingly. If you feel unwell, please seek emergency medical assistance.
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ICD implantation is generally a safe procedure, but a small number of patients may experience complications. The most common side effect is bruising at the procedure site, which occurs in less than 3% of cases. However, this may increase to up to 10% if you are taking blood thinning medications. While rare, there is a less than 1% chance of requiring a re-operation or a blood transfusion due to bleeding. In very rare cases, there is a risk of puncturing the lung during the procedure, which may result in a longer hospital stay and the insertion of a small drainage tube into the chest for a few days.
Occasionally, the leads may shift out of position within the heart, which occurs in approximately 1% of cases, and a repeat procedure may be necessary to reposition them. Infection is another rare (<1%) but serious risk that is always taken into consideration, and the device may need to be removed if infected. Finally, electromagnetic interference can prevent the device from working effectively.
There is a low risk of death, estimated to be less than 1 in 500. Long-term risks include infection or erosion, lead failure, inappropriate detection of an arrhythmia, and premature battery depletion or device failure. In some cases, ICD treatment may not completely resolve an arrhythmia, and you may still experience symptoms such as lightheadedness, dizziness, or fainting.