Aortic Valve and
The aorta is the main artery which transports all of the blood from the heart and distributes it throughout the body. The aortic valve is situated at the base of the aorta and controls the flow of blood out of the heart. Surgery is required if the aortic valve fails to open (aortic stenosis) or close properly (aortic regurgitation), or if the aorta is enlarged (aortic aneurysm).
Who needs this procedure?
Patients with aortic valve dysfunction who are experiencing symptoms of shortness of breath, dizzy spells or chest discomfort (angina) should undergo valve replacement to improve their survival and to alleviate their symptoms. Some patients may be candidates for this procedure to be performed minimally invasively which can offer less pain and a faster recovery for the patient.
TAVI is reserved for patients that are too high risk for open or minimally invasive surgery and this is because we don’t yet know the long-term results of this relatively new procedure.
The patient would need an open valve replacement if:
- The patient requires double or triple valve surgery
- The patient requires coronary bypass surgery
- The patient has undergone previous heart surgery
- The patient presents with a dilated aorta (aneurysm)
What is involved?
Open aortic valve surgery is performed under general anaesthetic through a vertical incision down the middle of the breastbone (sternum) to expose the heart. The patient is connected to a heart-lung machine which pumps blood through the body whilst the heart is stopped to operate on it.
The operation takes approximately 3-4 hours. The aorta is opened and the diseased aortic valve is removed taking care not to injure important nearby structures. A new valve is then sewn in place and the aorta is closed. The heart is restarted and the function of the new valve is assessed using an ultrasound (echocardiogram) to ensure that it is opening and closing appropriately. Once the surgeon is satisfied that the new valve and the heart are working well, the heart-lung machine is stopped and the sternum and skin can be closed. The patient is then transferred to the intensive care unit for close monitoring once they are stable.
Aortic Valve Replacement
The faulty valve is replaced with an artificial valve from these two broad categories: tissue valves and mechanical valves.
Generally, patients under the age of 60 will choose a mechanical valve and patients older than 65 will choose a tissue valve due to the differences in longevity of the valves and the need to be on blood thinners. In younger patients, tissue valves are found to be less durable for reasons that aren’t completely clear but may relate to their stronger immune system. When the valve fails a repeat surgery is generally required to place a new valve.
With newer technologies emerging we can now replace the deteriorated valve via catheter techniques and avoid surgery completely, however not all patients are suited to this new technology and each patient has to be assessed individually for suitability.
A mechanical valve will essentially last forever mechanically but requires the blood thinner warfarin for life. This is because the natural blood clotting system ‘sees’ the mechanical valve as foreign and will form a clot. If there is clot formation on a valve it can cause a catastrophic failure. Warfarin is a strong blood thinner that requires regular blood testing to monitor its effect and increases the risk of bleeding with trauma and surgery.
Ultimately, the choice of valve is individual and Dr Bassin will discuss this with each patient in detail.
- Is made from cow or pig material
- Is more usually suitable for patients over 65
- Will usually last for 10 years before needing a replacement
- No long-term requirements to take blood thinners
- Is sometimes referred to as a metal valve, but is actually constructed from pyrolytic carbon
- Is more usually suitable for patients under 60
- Will last mechanically forever
- Requires the patient to take the blood thinner ‘warfarin’
Who needs this procedure?
Patients generally require surgery if the aorta in the chest has reached 5.5cm in diameter. Additionally, if patients require an aortic valve replacement, then the aorta should be replaced if it has reached 4.5cm in diameter. This is measured on ultrasound (echocardiogram) or CT scans. These are guidelines and not clear-cut rules as it will depend on the individual patient circumstances – for instance, an aorta of 5.5cm is not as much of a problem for a patient who is very tall as opposed to a patient who is shorter – we expect the taller patient to have a larger aorta.
What is involved?
The aim of the operation is to remove the aortic aneurysm and replace it with an artificial aorta usually constructed from a woven fabric called Dacron. It is major open heart surgery and is performed under general anaesthetic through a vertical incision down the middle of the breastbone (sternum) to expose the heart. The patient is connected to a heart-lung machine which pumps blood through the body whilst the heart is stopped to operate on it. In many cases the body is cooled down to allow for a decrease in blood flow to the brain whilst the aorta is replaced. This is because it is impossible to replace the arteries to the brain whilst they have a continuous flow of blood.
What is the recovery like?
The operation can take between 5 and 12 hours depending on the extent of the aneurysm. Aortic aneurysm surgery is major open heart surgery. The hospital stay and recovery period are usually similar to other open heart surgeries. After experiencing an aortic aneurysm patients will be monitored life-long with CT or MRI scans to ensure that any remaining aorta is not enlarging.
What are the benefits and risks of this procedure?
Aortic aneurysm surgery has been performed since the 1960s with excellent results. The risks depend on the extent of the aneurysm with replacement of the ascending aorta being lower risk and replacement of the aortic arch being higher risk. For patients who are otherwise well the risks of surgery on the ascending aorta include: death (3%), stroke (3%), significant wound infection (1%), kidney injury (5%), requirement for a permanent pacemaker (3%) and blood transfusion (50%). The risk is higher for more extensive aortic aneurysms and if the patient has other co-morbidities including advanced age, previous heart disease or stroke, lung disease or having undergone previous cardiac surgery.
Dr Bassin will explain these risks to you in person as they pertain to your condition.