OUR PROCEDURES
Cardiac Surgery
- Coronary Artery Bypass Grafts (CABG) & Cardio-pulmonary Bypass (CPB)
- Off Pump Coronary Artery Bypass Graft (OPCABG)
- Valve Replacement and Repair
- Trans-catheter aortic valve implantation (TAVI)
- Minimally Invasive Direct Coronary Artery Bypass (MIDCAB)
CABG + CPB
In coronary heart disease, the arteries become blocked with atheroma. This decreases the blood flow to the heart, and angina or a heart attack may ensue. Coronary artery bypass grafts or CABG is a procedure carried out to improve blood flow to the heart by using healthy blood vessels transferring and grafting them to the hearts blood supply system.
The left side of the heart is responsible for pumping blood, oxygen and nutrients around the body. Consequently, it uses a lot of oxygen as fuel in this process. If an artery blocks on the left side, it is a serious problem, as the pumping mechanism will not be as effective as it should be. For the majority of patients undergoing grafting, an artery is used from another part of the body, commonly the saphenous vein in the legs or the left internal mammary artery. This is found underneath the chest wall. This graft is generally placed in one of the arteries called the left anterior descending artery. This artery is extremely important for the left ventricle; using the internal mammary artery at this point confers a greater chance of the graft remaining patent.
This procedure is carried out under general anaesthetic. The surgeon makes an incision down the middle of the chest (sternotomy) in order to gain access to the heart and lungs. In order for the grafts to be adequately attached to the arteries, the heart is stopped (a process called cardioplegia) and the body's blood and circulation is transferred to a cardio-pulmonary bypass machine. This specialised equipment takes over the role of the heart whilst the surgeon attaches the grafts. At the end of the operation, the heart is restarted again.
The procedure can take anything from 3-6 hours, depending on the severity of heart disease and the number of grafts required. Patients are routinely transferred to the intensive care unit to recover following this procedure.
Off Pump Coronary Artery Bypass Graft
Off Pump Coronary Artery Bypass Graft differs from CABG in that a cardiopulmonary bypass machine is not used to oxygenate and pump blood around the body. When the heart is accessed using a sternotomy (an vertical incision down the middle of the chest), depending on the severity and difficulty in accessing the blocked arteries, the surgeon may choose to keep the heart beating as opposed to using a heart lung bypass machine. This is called “beating heart surgery”. As the name suggests, the heart is allowed to beat during surgery, and only a small area of it is immobilised by a special suction device.
Generally, patients undergoing beating heart surgery have a quicker recovery and spend less time in hospital than those who have been on a cardio-pulmonary bypass machine. This is because of the physiological insult to the body on having the blood passed through an external circuit (a bypass machine) and back into the body.
The Wellington Hospital is proud to be able to provide this procedure with the aid of our highly specialised cardiac surgeons and appropriate state of the art equipment.
Valve replacement and repair
For most people suffering from valve disease, the first step in treating it is with medication. This is because many of the new drugs used to treat heart failure and valve disease are very effective. However, as the disease progresses, it is likely that valve surgery is required. There are 2 basic forms of valve surgery:
- Valve repair
- Valve replacement
Valve repair is more likely to be used for a damaged mitral valve. The mitral valve regulates the forward flow of blood from the left atria into the left ventricle. The aortic valve can also be repaired, but it is far more likely to be replaced with either a mechanical valve or a tissue valve. Modern mechanical valves are manufactured from carbon fibre. They are extremely strong as they have to be able to withstand the internal pressures placed on them by the beating heart. Because mechanical valves are not made from human tissue, the blood flow over these valves has a greater propensity to clot; therefore life long anticoagulation is required. If a tissue valve has been used, it is unlikely that anticoagulation will be required after 2-4 weeks following surgery.
In order for the heart to be exposed, an incision is made down the middle of the chest. The heart is then stopped and the circulating blood is pumped through a cardiopulmonary bypass machine. This machine takes over the function of the heart and lungs when the heart has been stopped. The heart valve can then be exposed, removed and a new artificial valve placed in position. Once the heart has been closed again, the heart is restarted and the chest cavity can then be closed. Operations of this kind will require intensive care support generally for 24-48 hours in routine cases.
Mechanical valves are more robust than tissue valves. Although they require the use of anticoagulants for life, they are designed to last a lifetime. Tissue valves, depending on the patients post operative lifestyle will generally need changing in 10-15 years.
Trans-catheter aortic valve implantation (TAVI)
Trans-catheter aortic valve implantation (TAVI) is a minimally invasive ('keyhole') procedure for replacing narrowed aortic valves. This is particularly useful for people in whom the risks of conventional open heart aortic valve replacement surgery would be high.
The aorta is the main artery coming out of the heart, carrying blood to the whole of the body (see diagram). The aortic valve sits at the junction between the heart and the aorta. Each time the heart beats it contracts to pump blood though the aortic valve which opens to let blood through and then closes to prevent blood flowing back into the heart. In some people the aortic valve can thicken and stiffen over time and this makes it more and more difficult for the heart to pump blood through the narrowed valve. This is called 'aortic stenosis' and patients with this problem experience shortness of breath and or chest pain on exertion and may also have dizzy spells or collapses.
Conventional aortic valve replacement surgery is a tried and tested treatment with excellent results in many patients but it is a major heart operation which involves opening the chest ('sternotomy') and going on the heart-lung bypass machine, and in some people the risks of such an operation are prohibitively high. In these patients trans-catheter aortic valve implantation is an excellent alternative. This procedure was first performed in 2003 and it is currently reserved for elderly patients and for those in whom the risks of conventional surgery are high because at present we do not know the long term (over 5 years) outcome. This is likely to change as the results of long term research studies become available.
There are 2 different makes of valve, the Sapien Trans-catheter Heart Valve made by Edwards Lifesciences and the CoreValve made by Medtronic, both of them involve soft pliable valve leaflets attached to a rigid frame. The leaflets are made from bovine (cow) or equine (horse) tissue; specifically pericardial tissue which is the sac that lines the outside of the heart. The frames are made from either stainless steel or a material called nitinol. The valves are compacted down so that they can pass through small holes - 'keyholes'.
Edwards SAPIEN XT™ Transcatheter Heart Valve
www.edwards.com
The TAVI Procedure: There are 2 main options; the trans-femoral and the trans-apical approach
The Trans-femoral approach: A wire is passed through a small cut in the skin and into the artery at the top of the leg – the ‘femoral artery’. The wire is then pushed up the artery to the heart, across the narrowed aortic valve and into the main pumping chamber of the heart – the ‘left ventricle’. The compacted replacement artificial valve is then tracked along this wire into position where it is expanded into shape, crushing the old valve to one side leaving the new normally functioning valve in its place.
To view an animation of the trans-femoral approach please click the play button below.
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The Trans-apical approach: In some people the femoral arteries are narrowed or are simply not big enough for the artificial valve to be passed through and the trans-apical approach can then be used. This involves a small cut in the left side of the chest, a wire is passed through this, straight through the wall of the heart into the pumping chamber of the heart and then across the aortic valve. The compacted replacement valve is then tracked along the wire as per the trans-femoral approach. The heart wall is made of muscle and at the end of the procedure when everything is taken out the hole is closed by a combination of a few stitches and the muscle springing back into shape.
To view an animation of the trans-apical approach, please click the play button below.
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The Anaesthetic: Usually the procedure is performed under general anaesthetic but under some circumstances patients are awake and a local anaesthetic is used.
The Team: Trans-catheter aortic valve implantations involve a team of cardiologists, cardiac surgeons and anaesthetists who all have substantial experience in performing the procedure. For further information and for details of the consultants carrying out this procedure at The Wellington Hospital, please contact the hospital enquiry line on 0207 483 5148.
MIDCAB
Recent technological advances in cardiac surgery are starting to have an impact on the way in which cardiac surgery is carried out. Traditional cardiac surgery necessitates the use of a large incision down the middle of the chest. The ribs then need to be split and retracted out of the surgical field. The heart is then exposed and either stopped and the blood routed through a cardiopulmonary bypass machine, or isolated as in beating heart surgery. Minimally Invasive Direct Coronary Artery Bypass is now a viable option for some patients.
The procedure does not require as large an incision as with CABG, instead a smaller 10-12 cm incision is made over the left side of the chest. The left internal mammary artery is then harvested to use as the graft vessel. The heart is kept beating with this form of surgery but a special device isolates the portion of the heart being grafted. The graft can then be placed to bypass the diseased or occluded coronary artery.
Because this technique can only be used for treating one or two grafts, it is not an option open to all patients unfortunately. The Wellington Hospital is proud to be the only independent sector provider able to facilitate this procedure with the aid of our highly specialised cardiac surgeons and appropriate state of the art equipment.