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.
Atrial fibrillation (AF) can cause stroke because blood cannot flow through the upper chambers of the heart (atria) smoothly. With sluggish blood flow, blood clots may form in the atria, especially the left atrium. These blood clots can break away from the heart and travel through the blood vessels.