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.
What causes heart block? Heart block can be caused by: Scarring (fibrosis) of the heart's electrical system caused by aging. This is the most common cause of heart block. Heart attacks. Infection of the heart valves (endocarditis). Complication of Lyme disease. Sarcoidosis or hemochromatosis.