7 | Valve disease

This book is primarily about heart health and coronary artery disease. Sometimes heart valves become diseased, so a brief account of valve problems and their treatment is provided here.

The heart contains four valves which are designed to make sure that the blood flows one way only (see Figure 1.2 on p. 6). Disease of the valves will distort the normal function of the heart. The two valves that are the most important are the mitral and aortic valves and these are the most commonly affected (see Chapter 1 for information on anatomy). Sometimes both can be affected at the same time. Each year 5000 people in the UK have valve surgery.

Two disorders can sometimes affect the aortic and mitral valves:

•they can leak (this is called incompetence);

•they can narrow (this is called stenosis).

The aortic valve normally has three flaps (leaflets) but some people are born with two and this causes early wear and tear. The normal three-leaflet valve may also harden up or become leaky with age. This can occur independently of coronary artery disease.

CAUSES

I have been diagnosed with valve disease. What do you think is likely to have caused it?

There are several causes of valve disease.

•Mitral stenosis (narrowing) can be caused by rheumatic fever. This condition, usually experienced in childhood or teens, can inflame the valves and lining of the heart, leaving permanent damage.

•Mitral incompetence (leaking) may be the result of rheumatic fever, bacterial infection (see below), a weakness of the valve supports causing the leaflets to flop backwards, or a narrowing of the coronary arteries.

•Aortic stenosis may be due to rheumatic fever, being born with an abnormal valve (congenital) or age (wear and tear).

•Aortic incompetence may be due to rheumatic fever, high blood pressure, bacterial infection, age, or being born with an abnormal valve.

SYMPTOMS

How will I recognise valvular disease?

If the aortic valve narrows, this can cause angina, breathlessness and blackouts, whereas, if it leaks, it usually causes the heart to enlarge and breathlessness then follows. If you feel tired and breathless on exertion, it is probably a good idea to go to the doctor for an opinion or tests. Valve disease may cause heart failure (see Chapter 5).

A severe mitral valve leak or narrowing will also cause breathlessness.

Both valves can become infected (see the section Infection below).

Does the fact that I have valve disease mean that there is a greater strain on my heart?

Yes. As a result of either narrowing or leaking, or both, the abnormal valves increase the work that the heart has to do. If the valve is narrowed, the pump must generate higher and higher pressures to get the blood through. If the valve leaks, the pump must put out more blood with each beat: it must pump out the 5 litres that the body needs each minute plus the volume that has leaked back.

TESTS

I have been asked to go for tests to see if I have valve disease. What will these involve?

The doctor can usually hear heart murmurs and will confirm the diagnosis with echocardiography (see Chapter 5). Sometimes a murmur is heard and a problem detected by chance. The echocardiogram provides a comprehensive picture of your heart, telling us about any valve leaks or narrowing and their severity. If your valve condition is not too bad, it can be watched by the echocardiogram at 12- or 6-monthly intervals. If the echo identifies a severe problem, you will be offered further investigations and possible surgery.

TREATMENT

Valve conditions that are not severe can initially be treated medically. Diuretics (water tablets: see Chapter 2) are used to relieve breathlessness; digoxin may be used if there is atrial fibrillation (Chapter 6), when warfarin will also be used. If the main problem is a leaky valve, ACE inhibitors (see Chapter 2) may be used to try to reduce the leak. They act to open up the arteries so that blood leaving the heart meets less resistance, with the idea being to make it easier for blood to flow forwards rather than leak backwards.

I have had tests for valve disease and have been put on a waiting list for a new valve. It all sounds rather frightening –what will this involve?

Valve surgery is routine for the surgeon but a daunting experience for anyone about to undergo it! The surgeon should discuss with you the risks to you individually (if he doesn’t, ask him) and explain what sort of valves are available and what the options are.

Preparation is similar to that for a coronary bypass operation (see Chapter 2). Your breast bone (sternum) will be cut along its length and your heart stopped; you will then be put on a bypass machine while your heart is being operated on. The surgeon will open up your heart to get access to the valves as these are located inside the heart. Sometimes a leaking mitral valve can be repaired and surgeons will do this if at all possible. Otherwise, an artificial valve is put in after the diseased valve has been cut out.

Your hospital stay will usually be 7–10 days. All heart surgery is a ‘big operation’ but we are lucky these days to have perfected the techniques and the risks are therefore minimised.

What are artificial heart valves like?

There are two sorts of valves used – tissue valves and mechanical valves. The decision as to which sort of valve to use will be made by the surgeon at the time of the operation, because it’s only then that a considered decision can be made. The surgeon will have explained the differences to you beforehand, and you can indicate your preference should the surgeon have a choice when the operation is being performed.

•Tissue valves are made of natural tissue from humans, cows or pigs. They are treated to avoid rejection later.

•Mechanical valves are usually made of carbon fibre (but are often called metal or plastic valves) and contain no natural tissue. They may click.

A big difference between the two types is the need for warfarin, needed for ever if you receive a mechanical valve, whereas aspirin is all that will be needed if a tissue type is used (unless you are in atrial fibrillation).

How long do these different types of valve last?

Mechanical valves last many years and rarely go wrong. Tissue valves can wear out after 10 years but the more modern ones last longer. Tissue valves are easier to live with but the chances of needing a repeat operation are higher.

It sounds like a big operation. What are my chances of pulling through?

Survival after a single valve replacement is 96%. There may be a slightly increased risk if coronary surgery is needed at the same time. This is more likely in older patients. Without an operation to replace a severely diseased valve, few people live beyond 2 years and quality of life is poor with a relentless downhill slide. Valve surgery will offer you an excellent chance of being alive and well 10 years on.

What happens if something goes wrong later? Can valve operations be repeated?

Yes. Repeat operations are generally safe to do and about 10% (one in ten) tissue valves need redoing after 10–15 years.

Do all diseased valves need an operation?

No, many minor problems never cause any concern. However, you will be checked regularly just in case these problems worsen. Even badly damaged valves need not be operated on straight away; the cardiologist will keep an eye on your condition and action will only being taken when symptoms become a problem.

Are there any other types of surgery for valve disease? I have been told there is something called ‘balloon surgery’. What is this?

Leaking valves will need surgery. A narrow mitral valve, however,
can be widened with a balloon. The decision to use a balloon depends on what is found when you have transoesophageal echocardiography (see Chapter 3). If your case is suitable, a balloon operation on the mitral valve (mitral valvuloplasty) will be as successful as surgery.

Mitral valvuloplasty takes place in the cardiac catheter laboratory with a technique similar to coronary angioplasty (see Chapter 3).

Under local anaesthetic, the vein at the top of the leg is used. The vein goes into the right atrium which is separated from the left atrium by the atrial septum (see Chapter 1). The mitral valve lies between the left atrium and left ventricle, so the balloon needs to be in the left atrium in order to find its way through the valve. The septum is in the way, so a small hole is made in the atrial septum with a special needle which allows the cardiologist to position a large balloon behind and then through the valve. This method is necessary as the valve opens away from the cardiologist allowing the balloon to be passed forwards into the opening – the cardiologist more or less floats the balloon through as the valve opens with the blood flow. The balloon is blown up in the valve which is then split open along the flaps that have become stuck together. When the balloon and tubes are removed, the cardiologist will press on your groin over the vein to stop the bleeding. No stitches are used. If there are no complications, you will go home the next day.

If you can balloon a narrow valve without heart surgery, can you replace valves also?

Recently, techniques have been developed in very specialised centres to repair a leaking mitral valve and replace the aortic valve, using access from the vein or artery in the groin. It is very early days and these procedures are mainly used in people who are unfit for conventional heart surgery.

INFECTION

I am about to undergo valve surgery. Are there any problems associated with valve replacement?

Heart valves can become infected and this is known as bacterial endocarditis (pronounced ‘en-doe-car-dye-tiss’). It can affect replacement valves and your own valves if they are diseased. Infection is not common but it is preventable. Your teeth and gums must be kept healthy: regular dental check-ups are needed. Bugs can enter the bloodstream via tooth decay while you are chewing. If you are considered a high risk case, any operative procedure that you undergo should be covered by a course of antibiotics to protect the valves – the medical term for this is antibiotic prophylaxis. Special antibiotic preparations are available on prescription. Check with your doctor.

Though rare, an infection that damages a valve is very dangerous and only half of infected people survive. As infection is preventable, this is one of those times when prevention really is life-saving. Recently the National Institute for Clinical Excellence (NICE) has declined to recommended antibiotic prophylaxis for people at increased risk of endocarditis when they undergo dental procedures, but emphasised the importance of maintaining good oral health.

I had a valve replacement some months ago. How will I know if I have developed an infection?

Infections develop slowly but you will increasingly notice these symptoms:

•raised temperature;

•sweating at night time;

•feeling more and more ill;

•weight loss;

•poor appetite;

•joint aches and pains.

If you develop any of these symptoms, go straight to your doctor. If the doctor suspects endocarditis, he will send you directly to hospital.

When I was in hospital for a valve replacement, one of the patients there had developed an infection. Is infection common? Is it likely that I shall develop an infection too?

It is not common, but it is preventable. Apart from maintaining oral health, you should avoid tattooing and body piercing. If it is caught early, 50% of people will recover. Therefore, you should always be aware of the possible problems and symptoms. If you develop any of the symptoms discussed above, go straight to your doctor. You can get a credit card-sized warning card from the British Heart Foundation (see Appendix 2).