Shortness of breath is a very common symptom. It may be due to lack of fitness and ageing. On the other hand there may be many medical conditions associated with breathlessness. These include anaemia, muscle disorders and lung abnormalities. A weakness of heart muscle causing reduced pumping strength of the heart may also cause breathlessness. The symptom may occur when patients walk but may also be noticed when lying flat, particularly at night. There may be associated swelling of the abdomen (tummy) and ankles. Breathlessness may also be caused by disease of the heart arteries with blockages in the heart arteries leading to a weak contraction of the heart. Other cardiac causes of breathlessness include heart valve disease and inherited abnormalities of the heart (cardiomyopathies).