Implantable Cardiac Defibrillators

What is an Implantable cardiac defibrillators?
A defibrillator is a specialized pacemaker that can not only be used to treat slow heart beats, but in certain people can treat life threatening fast heart beats.It can terminate these rhythms by pacing rapidly or ultimately delivering a shock. The device is larger than a pacemaker and is inserted in the same way, with conscious sedation under local anaesthetic . The defibrillator may need to be checked to make sure it is working and can terminate severe rhythm problems. This is performed under a short general anaesthetic.

After implant ,driving and sport is restricted for a short period of time, but most people are able to resume normal activity and a normal lifestyle once the device is stable and checks are normal. Most devices can be home monitored, which adds an element of safety to the devices and alerts your cardiologist about premature lead failure, arrhythmias and battery status remotely. The newer devices are MRI compatible

You will be required to have periodic defibrillator checks at an outpatient clinic. These checks are performed in a clinic using computers to communicate with the defibrillator. The devices can be programmed in a number of ways and are often individualized to your specific needs and lifestyle. You will be given a defibrillator identification card which is the size of a credit card and should be kept with you at all times. If you have any further queries , these should be discussed with your cardiologist.

Implantable Cardiac Defibrillators

Permanent Pacemaker

What is a Permanent Pacemaker?
A Pacemaker is a small electronic device which is implanted under the skin. It communicates with the heart via pacing leads. It is used in situations where the heart beat is too slow or does not increase with exercise .

Most pacemakers are inserted under local anaesthetic with conscious sedation.. An inscision of approximately 5 centimeters is made under the collar bone and a small pouch is burrowed under the skin. The leads are inserted through the arm veins into the heart. One to three leads are inserted depending on the underlying heart disease. The newer pacemakers can be home monitored and most are now compatible with MRI scanning.
After pacemaker insertion patients are encouraged to lead a normal life. After a short period of time driving , sport and usual physical activity can be resumed.
Pacemaker batteries last 10 to 12 years, but battery life can vary according to amount of time pacing is required.
Regular pacing checks are required to monitor leads, arrhythmias and battery life. The pacemaker checks are performed in a clinic using computers to communicate with the pacemaker. The devices can be programmed in a number of ways and are often individualized to your specific needs and lifestyle.

You will be given a pacemaker identification card which is the size of a credit card and should be kept with you at all times.
Any further queries should be discussed with your cardiologist.

Permanent Pacemaker

Structural Heart Intervention

(CLOSURE OF HOLE IN THE HEART, REPLACEMENT OF BLOCKED AORTIC VALVE AND CLOSURE OF LEFT ATRIAL APPENDAGE): New procedures are now available as a proven solution for symptomatic patients suffering from the above conditions. These procedures are performed in the Cardiac Catheterisation Laboratory with the availability of general anaesthesia or heavy sedation if required. They are usually performed via the femoral artery and rarely require open heart surgery. The valve implant is reserved for elderly patients too frail for open heart surgery. In such patients there is a very small risk with the procedure but it has been very successful with a lower operative risk and quicker recovery than open heart surgery in this elderly patient group.

POST INTERVENTION MANAGEMENT: Patients will usually remain in the acute Coronary Care observation ward for monitoring of their heart rhythm over the 12 hours after the procedure. They will normally be mobilised on the following morning and be discharged on that day in most cases. It is extremely important for these patients to adhere to the recommended blood thinning medication with two anti-platelet medications to be taken for a minimum of 3 up to 6 months in cases where a drug eluting stent has been implanted. These stents will inherently take a longer time frame to heal into the wall and therefore need a longer duration of anti-clotting treatment for this reason.

Return to normal physical activities is usually possible within one week of the stenting procedure and patients will usually require cardiological follow-up within 1 to 2 months of their coronary intervention. It is mandatory that patients do not stop their blood thinning medication until instructed by the Cardiologist.

Structural Heart Intervention

Coronary Intervention

Initially coronary balloon angioplasty was the only intervention but now coronary stents are the most common treatment for significantly blocked coronary vessels. It is also possible to have a high speed diamond tipped drill passed through a calcified blockage to smooth the vessel wall and allow expansion with the deployment of a metal stent. The metal stent itself is a stainless steel or cobalt chromium slotted tube which is crimped onto a balloon. The balloon in a fully deflated form is passed through the coronary vessel and then positioned across the area of narrowing and fully expanded up against the wall at very high pressure up to 360 psi. This stent is then firmly wedged internally as a physical scaffold holding the artery open until a slow healing process has covered the struts of the stent with natural body skin. The stents are biologically inert and hence are not rejected by the body and most stents are now coated with various drugs which are designed to reduce the ingrowth of healing tissue to a minimum.

STENTING TECHNIQUE: After diagnostic angiogram pictures are obtained, a guiding photo is placed in front of the Cardiologist for accurate positioning of stents. Then, with the use of x-ray guidance, a guiding catheter is passed from either the wrist or the groin up to the entrance of the artery with the severe blockage. A very soft, thin guide wire is passed smoothly down the artery through the center of the blockage and positioned in the downstream vessel. A small sausage shaped balloon is passed across this guide wire in a deflated shape and positioned across the blockage and fully inflated to partially open the artery, the balloon is then removed leaving the wire in place and then a stent crimped on to a balloon is passed again over the wire and under x-ray imaging, the balloon is inflated to its full diameter to high pressure forcing the stent against the inside edge of the pipe acting as an internal scaffold and preventing any collapse of the arterial wall. Normal flow down the coronary artery is then demonstrated inside the stented segment to ensure that the artery is smooth throughout its length and then all the guide wire and balloon equipment is removed. During the balloon inflation inside the stent, patients may feel a transient tightness or chest pain which improves immediately after removal of the balloon. Importantly, some patients may have multiple blockages and therefore may require more than one procedure to achieve a complete re-opening of all blockages.

STENT TECHNOLOGY: After the initial enthusiasm for bare metal stenting some patients developed early regrowth of blockage inside the stent due to an exaggerated scarring or healing process. The promising development of a drug eluting stent led to the ability to control the body’s healing process and the ingrowth of scar tissue was minimized with the slow release of a drug from the surface of the stent over the first 8 weeks after stent deployment.

Even with this drug eluting technology, approximately 6 to 7% of drug eluting stents still develop excess scar tissue ingrowth associated also with some inflammation around the edges of the stent.

A further very promising new technology has led to the availability of a biodegradable stent which has tended to overcome these limitations of metallic stents.

This is a non metallic stent composed of a polylactic acid substrate which is self dissolving within a two year period of deployment leaving no trace of stent struts and a normally reactive healthy artery.

Coronary Intervention

Coronary Angiography

What is Coronary Angiography?
The coronary angiogram is a commonly performed invasive procedure designed to assess the blood flow to the heart muscle through the coronary arteries. It is the gold standard test for accurate measurement of narrowing of the coronary vessels.

The technique involves the patient lying on an x-ray table and then being prepared by sterile cleansing of the access site (either the wrist or groin area) then the applications of a large sterile sheet across the patient to prevent any infection. Under local anesthesia a plastic introducing sheath (with 2mm x 20mm length is inserted into the artery and then plastic diagnostic tubes (catheters) are passed from the access site internally and positioned in the entrance of the coronary arteries. A special dedicated x-ray tube is then positioned above the patient and x-ray pictures are acquired whilst dye is injected internally through the patient’s coronary vessels making a discreet and clear image of the patient’s coronary artery dimensions. The x-ray tube can be adjusted to reduce the dose of radiation to the minimum amount and is able to be moved in all direction with precise control.

During the performance of an angiogram the patient has special plastic electrodes placed comfortably on the skin to monitor the heart beat during the performance of angiography. The catheter tubes are changed to different shapes and passed across a soft curved guide wire which prevents any damage to internal organs and is painlessly passed up to the entrance of the heart. Once the left and right coronary vessels have been fully assessed, then a final specially coiled plastic tube is passed painlessly into the center of the left heart pumping chamber and with injection of the dye, the pumping action can be accurately assessed and a warm sensation may be experienced at this point. The catheters are then gently extracted from the access site and discarded.

At the end of the angiographic study, the introducing sheath is then gently removed from the radial or femoral artery. A local pressure band is applied to the radial artery after sheath removal or if the femoral artery is used either a self dissolving collagen plug or simple stitch is placed in the wall of the femoral artery to minimize any bleeding and a pressure device maybe applied for up to 30 to 60 minutes if required. This test is usually performed as a day only investigation and patients will usually be allowed to return home on the same day with strict instructions to minimize their mobility for the next 24 hours.

PROCEDURAL RISKS: In order to obtain the gold standard diagnostic information regarding the arterial circulation of the heart, a coronary angiogram represents a very safe test with a very small risk of causing arterial damage or significant bleeding in rare circumstances.

Coronary Angiography

Implantable Loop Recorder

What is an Implantable Loop Recorder?
A loop recorder is a small electronic implantable device used to diagnose causes of fainting where a cardiac rhythm disturbance is suspected. It can also be used to diagnose cardiac rhythm disturbances which occur infrequently and are difficult to record due to time between events.
It is implanted under local anaesthetic . The device is inserted under the skin over the heart and can record events for up to 3 years. Some devices can be remotely monitored and the data down loaded over the telephone.
Once the diagnosis is made the device can be removed .

Implantable Loop Recorder
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