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.
Although it can cause chest pain and other symptoms that are similar to a heart attack, atrial fibrillation doesn't lead to a heart attack. Instead, a heart attack (myocardial infarction) occurs when the coronary artery, which supplies blood to the heart, becomes blocked, depriving the heart of vital blood and oxygen.he irregular heart rhythm of atrial fibrillation can cause blood to pool in your atria and form clots. Although those clots won't lead to a heart attack, one of them could dislodge from the atria and travel through your bloodstream to your brain. There it might block blood flow, causing a stroke.