ERA. 1  baseball, baseball game - a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs; he played baseball in high school; there was a baseball game on every empty lot; there was a desire for National League ball in the area; play ball!.
The contraction of the heart muscle starts in the two atria, which push the blood into the ventricles. Then the walls of the ventricles squeeze together and force the blood out into the arteries: the aorta to the body and the pulmonary artery to the lungs.
Your heart is a muscle that pumps blood throughout your body, but it also needs its own blood supply. The blood vessels that provide oxygen-rich blood to your heart are called the coronary arteries. These arteries can become narrowed through build-up of plaque, which is made up of cholesterol and other substances. Narrowed arteries can cause symptoms, such as chest pain (angina), shortness of breath, and fatigue. If a plaque ruptures, a blood clot can form at the site of the rupture and block blood flow through the artery. This is a heart attack.