The second category of heart problems concerns the valves, which, like the parts of any machine, can malfunction in a variety of ways. As we have seen, blood must follow a programmed route and not flow back and forth. Once it has passed a certain point, on it must go, to return only when it has been full-cycle through the circulatory system. This is where the one-way action of the various valves is of paramount importance. Valve disease can give the heart surgeon many hours of repair work before the valves are set back in working order.

Contrary to popular belief, the commonest heart disease, taken worldwide, is either narrowing or leakage of the valves caused by rheumatic heart disease. Rheumatic heart disease is the sequel to rheumatic fever, which in turn results from an initial streptococcal infection (streptococci are a type of bacteria). The disease produces inflammation in the heart muscle and valves and can be quite severe, especially among children and teenagers. Fortunately, the incidence of rheumatic fever has declined in those countries where antibiotic treatments are readily available – but that still leaves many parts of the world with a young population at risk.

Valves can be impaired in other ways – as a result of syphilis, for instance – or a patient may simply have a congenital deformity of the valves, or may have acquired this as a sequel to coronary thrombosis. Whatever the cause, the effects may prevent the valve from opening fully (stenosis – ‘constriction’), or may stop it closing properly, allowing blood to leak back after it has come through, a condition known as incompetence. Both conditions present the heart with an unhealthily large workload. It has to pump harder to force blood through a stenosed valve or to maintain proper flow if blood is seeping back.

There is a further complication for people with a malfunctioning valve: they can sometimes succumb to infection of the valves, endocarditis. The infection is usually caused by bacteria and is often a consequence of receiving dental treatment. So, before they have their teeth treated, susceptible patients should take a precautionary dose of antibiotics.

*8/353/5*