When your electrical system is working normally, the two upper chambers of the heart (atria) contract and pump blood into the two lower chambers (ventricles) in a well-coordinated way. This results in ...

Though famous for their mid-air hovering during hunting, tiny hummingbirds have another trait that is literally telltale: males of some hummingbird species generate loud sounds with their tail ...

Atrial flutter is a type of irregular heartbeat, or an arrhythmia. It causes your heart to beat too fast. Atrial flutter doesn't always have symptoms, but it can sometimes have serious consequences if ...