Valvular diseases are the diseases of the valves of the heart. The function of the heart valves is to open and close properly during the cardiac cycle. This allows the passage of blood from one cavity to another and that can advance without retreating.
Valves can be damaged by infection, trauma, aging, etc. Years ago, the main cause was rheumatic fever, an infrequent disease now in developed countries.
The four valves of the heart that can have diseases are:
Mitral valve: separates the left atrium from the left ventricle
Aortic valve: separates the left ventricle from the aortic artery
Pulmonary valve: separates the right ventricle from the pulmonary artery
Tricuspid valve: separates the right atrium from the right ventricle