Nitroglycerin
Nitroglycerine is used mostly for angina and some heart attacks caused by coronary artery disease.  This is a disease that makes the blood vessels that bring blood to the heart get narrower.  When the heart does not get enough blood and oxygen, a person can have angina (chest pain) or a heart attack.  Taking nitroglycerine makes the blood vessels get wider again, so more blood and oxygen can get to the heart.