The document discusses cardiovascular diseases and provides information on the heart, its structure and function. It defines different types of heart diseases such as myocardial infarction, arrhythmias, congestive heart failure, atherosclerosis, congenital heart disease, and ischemic heart disease. Risk factors for heart diseases are described. Antihypertensive drugs and their mechanisms of action are explained. Specifically, the document discusses the cardiotonic agent methyldopa, providing its synthesis, mechanism of action, and uses for treating hypertension.