Valvular heart disease
The purpose of a heart valve is to allow blood to flow in one direction only between two distinct parts of the heart and the circulation. Normally, this means that it will let blood into a chamber or major vessel, but won’t let it back out the way it came in.
There are two broad ways in which a heart valve can become damaged:
• It can become narrowed (stenosis), so not enough blood can be pushed through the gap with each stroke of the heart; the heart tries to pump harder, putting it under extra strain.
• It can become leaky or incompetent (regurgitation). In this case, some blood will flow back into the chamber that it came from, so, again, the heart needs to work harder to pump enough blood out in the right direction.
In both of these conditions the heart has to work harder, as mentioned above. The consequence of the heart working harder is that it becomes bigger and bulkier, much like any over-exercised muscle. There is, however, a limit to how big the heart can become. Once the limit is reached, and if nothing has been done to treat the underlying condition, the heart will start to fail.
The medical term for the bigger, bulkier heart is ‘cardiac hypertrophy’. A large number of patients undergoing heart surgery have hypertrophy, but far fewer have hearts that have actually gone into failure. The risks of surgery are much higher for a patient in heart failure, so the timing of referral for surgery is crucial.
WHAT GOES WRONG
There are a large number of causes of valvular heart disease (VHD), some of which can cause either stenosis or regurgitation. Any of the four heart valves may become diseased, but the mitral or aortic valves are most often affected, and over 99 per cent of heart valve operations are on one or other of these. This is because they are both in the left side of the heart which is exposed to much higher pressures and stresses than the right side.
Some individuals may have a combination of valve diseases, for example, combined aortic stenosis and regurgitation is known as ‘mixed aortic valve disease’. Similarly, both aortic and mitral valves can be affected by disease in one person, and this is especially common when the cause is rheumatic fever.
The effects of valvular heart disease can range from easily tolerated to profoundly disabling. As we have seen, the underlying process continues to the point where the heart cannot cope any more and starts to fail, usually giving the initial symptoms of breathlessness and angina. After these symptoms, caused by left-sided heart failure, the right side may start to fail. Among other things, this will cause swollen ankles and legs, resulting from the backlog of blood trying to return to the heart from the rest of the body.
There is only so much that the heart can put up with and, unless something is done to relieve the strain on it, your condition will rapidly worsen. It is therefore important to recognise when you’re starting to get symptoms and to seek specialist help accordingly.
