Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Heart Valve Disease ?
    ### Response:
    Heart valve disease occurs if one or more of your heart valves don't work well. The heart has four valves: the tricuspid, pulmonary, mitral,and aortic valves.
                
These valves have tissue flaps that open and close with each heartbeat. The flaps make sure blood flows in the right direction through your heart's four chambers and to the rest of your body.
    