Heart health Heart Health Glossary Use this glossary from the National Institute on Aging to understand terms related to heart disease, heart attacks, stroke, and cardiovascular disease. What Is a Heart Attack? What is a heart attack? Know the symptoms—chest or upper-body pain, nausea, and more—and what to do in this emergency. Call 9-1-1 right away! What Is Heart Failure? Heart failure is a serious, common condition caused by other diseases or conditions that damage the heart muscle. Learn what happens during heart failure. Heart Health and Aging Find out how your heart works and how the heart and blood vessels change with age. Read about what heart disease is, and get some tips on how to prevent it.