Aortic Valve Replacement

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).

The Aortic Valve

The aortic valve allows blood to flow out of the heart into the aorta, to supply the entire body with the oxygen and nutrients contained in the blood. The valve itself is constructed of 3 leaflets which open and close like door flaps. The aortic valve can fail if it doesn’t open sufficiently (aortic stenosis) or doesn’t close causing the blood to leak back into the heart (aortic regurgitation). The most common reason why a patient would need a valve replacement is aortic stenosis. This commonly occurs with ageing as the valve leaflets become thickened and immobile with calcium. Some people are born with a bicuspid valve; a congenital malformation where the valve has only two leaflets. Bicuspid valves are more prone to failure due to the suboptimal function and is also associated with enlargement of the aorta (aortic aneurysm).

There are three main categories for aortic valve replacemen. These include open heart valve surgery where the breastbone is split open to replace the value, minimally invasive valve surgery through a small skin incision, and transcatheter aortic valve implantation (TAVI) where no surgery is required and the valve can be replaced via a catheter in the leg artery.

Diagnosis

Aortic valve disease may be picked up incidentally with a routine check-up when a doctor hears a ‘murmur’ in the heart with their stethoscope. Aortic stenosis is more common in patients over the age of 70 and this can often be monitored for years before surgery is required. Patients with bicuspid aortic valves (two leaflets) may develop aortic stenosis in their 40s or 50s as the abnormal valve is more prone to failure.

In other situations, patients may present to their general practitioner with shortness of breath on exertion and a new heart murmur is discovered. They will be referred to a cardiologist who will perform an ultrasound of the heart – an echocardiogram. This will provide a detailed look of the interior of the heart – its function and the degree of aortic regurgitation or stenosis.

Once a patient starts experiencing symptoms such as shortness of breath or dizzy spells, they would be referred to a surgeon for consideration of valve replacement. Alternatively if someone has severe aortic regurgitation or stenosis, even without symptoms, they may be referred to a cardiothoracic surgeon for consideration of valve replacement.

Open Heart Surgery

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 they also require surgery to their mitral or tricuspid valve. Additionally, open surgery would be the best option for patients who have any blocked arteries which require bypass surgery, any previous heart surgery or a dilated aorta (anuerysm).

What is involved?

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.

Tissue Valve

A tissue valve is made from cow or pig material. This type of valve is usually more suitable for patients over the age of 65 as it lasts for approximately 10 years before needing a replacement and redo valve surgery. There is also no long-term requirements for the patient to take blood thinners.

Mechanical Valve

A mechanical valve is sometimes referred to as a metal valve, but is actually constructed from pyrolytic carbon. This valve more suitable for patients under the ago of 60, as they can last forever and don’t need a redo operation. The patient will need to take the blood thinner ‘warfarin’ to ensure the valve functions properly.

What is the recovery like?

The operation takes approximately 3-4 hours and you will wake up in intensive care later that day or the next morning. Small tubes to drain any residual fluid from around the heart will be placed in your neck, as well as intravenous lines, to sample blood and administer medications. These tubes and lines will be removed after 1-2 days and then you will be transferred to the ward to continue your recovery. Once on the ward, the goal is to monitor your blood pressure and heart rate and ensure adequate mobilisation. We work very closely with our nurses, physiotherapists and occupational therapists to work on breathing exercises and functional mobilisation. Every patient is different and the assistance is tailored to your needs. Many patients are discharged home after a week but there is a significant number of patients, particularly the elderly who find it easier to transition home after a short stay in a rehabilitation hospital. Once at home, patients are encourgaed to take plenty of walks and to generally take it easy. Your body will let you know what it is capable of and there is no need to push it during this recovery period. For the first 6 weeks there are precautions to be taken whilst the bone is healing. Lifting should be limited to 3kg and patients are encouraged to sleep on their back. Any activity that requires heavy use of the arms is generally discouraged. Patients generally go back to work after 4-6 weeks and complete recovery is achieved by 3 months.

What are the benefits and risks of this procedure?

Open heart aortic valve surgery has been performed since the 1960s with excellent results. We have continued to improve the safety of surgery but there are still risks. For patients who are otherwise well the risks of surgery include: death (1%), stroke (1%), significant wound infection (1%), kidney injury (2%), requirement for a permanent pacemaker (3%) and blood transfusion (25%). The risk can be higher if patients have other co-morbidities including advanced age, previous heart disease or stroke, lung disease or having undergone cardiac surgery previously. Dr Bassin will explain these risks to you in person as they pertain to your condition.

When can I drive?

You may drive 4 weeks following surgery, according to the national guidelines.