The heart has 4 chambers.
Valves control the flow of blood from the atria to the ventricles.
It usually starts suddenly. Your doctor will try to find out the cause of the fast heart rate. Whether the cause is found or not, you may still need to take medicine to control the problem. However, you will still be able to live a normal life. Among the possible causes are valve disease, hardening of the arteries, thyroid disease, or heart failure.