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.
Blood clots originating from inside the heart can be fatal. Photo Credit heart image by jim from Fotolia.com. In 1875, blood clots in the heart were found to cause strokes. It was established that blood clots were not only capable of developing in arteries and veins, but inside the heart as well.