The West Nile virus multiplies in the human blood stream and is carried to the brain, where it begins to affect the central nervous system and causes inflammation of brain tissue, known as encephalitis. If this happens, a person will develop high fever, headaches, swollen lymph nodes and stiff neck.
With each heartbeat, the heart contracts (or squeezes) and relaxes. Every contraction pushes blood out of the two pumping chambers (ventricles). When when heart relaxes, the ventricles refill with blood. The ejection fraction (EF) refers to the amount, or percentage, of blood that is pumped (or ejected) out of the ventricles with each contraction. This percentage, or EF number, helps your health care provider determine if you have heart failure or other types of heart disease.
With each heartbeat, the heart contracts (or squeezes) and relaxes. Every contraction pushes blood out of the two pumping chambers (ventricles). When the heart relaxes, the ventricles refill with blood. The ejection fraction (EF) refers