Changes

'''Coronary heart disease''' (CHD) is disease which is caused by a narrowing of the small blood vessels that supply [[blood]] and [[oxygen]] to the heart.

'''Coronary heart disease''' (CHD) is disease which is caused by a narrowing of the small blood vessels that supply [[blood]] and [[oxygen]] to the heart.[http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004449/]