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.
1 This makes the condition worse as the heart muscles require more nutrients to work and the myocardial muscles pump at an increased rate. 2  Stroke volume reduces as the systole or diastole contractions start to fail. 3  If the volume of blood in the ventricle at the end of systole rises, it means less blood is ejected.