Valve defects refer to abnormalities or malfunctions in the heart's valves, which are crucial for regulating blood flow. These defects can lead to conditions such as valvular stenosis, where a valve narrows and restricts blood flow, or valvular regurgitation, where a valve fails to close properly, causing blood to leak backward. Common causes of valve defects include congenital heart defects, infections like endocarditis, and age-related changes. Symptoms may vary but can include fatigue, shortness of breath, and swelling in the legs. Diagnosis often involves imaging techniques such as echocardiograms to assess valve function and structure.