The most direct effect on the heart comes from blockages, such as atherosclerosis or embolism , that prevent oxygenated blood from supplying the heart muscle, which quickly dies. The general name for sudden loss of heart action from these causes is heart attack . Heart attack and the slower developing and more persistent Heart failure , which is often caused by atherosclerosis as well, combine as the leading cause of death in most industrialized countries, producing far more deaths than any other cause in the United States. Among the bacteria most likely to damage the heart are strep which can cause a general infection often known as rheumatic fever . People who already have damaged valves, producing an audible heart murmur when a stethoscope is used, are more susceptible to bacterial infection of the heart and need to take special precautions to avoid it.
Hypertension is often the cause of heart disease, as well as of other serious organ failures.
The heart is susceptible to various genetic and developmental problems as well. Some, such as aortic stenosis, are strictly diseases of the heart, while others, such as Down's syndrome or Marfan's syndrome , are pervasive disorders that usually affect the heart along with other organs. A wound to the heart is among the most dangerous of events, usually resulting in death in a matter of moments. Electric shock can also stop a heart from beating. In many cases a heart that has been stopped from beating for a brief period can be restarted.