Your heart beats around 100,000 times every day and, in that time, pumps about 23,000 litres of blood around your body. But what happens when it doesn’t work as well as it should? This unit explains what happens in cardiovascular disease, when the heart’s performance is affected, how the normal function of blood vessels is impaired, and what treatments are available. Whether you are a patient, relative, friend or healthcare professional, you will find the unit interesting. This study unit is just one of many that can be found on LearningSpace, part of OpenLearn, a collection of open educational resources from The Open University. Published in ePub 2.0.1 format, some feature such as audio, video and linked PDF are not supported by all ePub readers.