The study aims to evaluate the feasibility and safety of polymer artificial heart valve designed and developed by Shanghai HeartEpoch Medical technology Co. Ltd. for the treatment of the mitral valve diseases.

Inclusion Criteria:

1. ≥ 60 years old;
2. severe mitral regurgitation or severe mitral stenosis confirmed by ECHO;
3. surgical mitral valve replacement;

Exclusion Criteria:

1. LVEF < 50%;
2. History of cardiac surgery or history of cardiac intervention( within 1 year), Concurrent cardiac surgery(excluding tricuspid valve repair surgery or atrial fibrillation ablation) or cardiac interventional procedures;
3. STS ≥8；
4. intracardiac mass, thrombus or neoplasm confirmed by echo;
5. Coronary artery disease that requires revascularization；
6. A pacemaker need to be implanted;
7. Severe macrovascular lesions require surgical treatment;
8. Patients with active bleeding, bleeding tendencies or those who are unable to receive anticoagulant therapy；
9. There was evidence of acute myocardial infarction within 1 month before the surgery (Q-wave MI or non-Q-wave MI, CK-MB ≥ twice the normal level and/or elevated troponin)；
10. here was a history of cerebrovascular events (CVA) within 1 month before the surgery, including ischemic and hemorrhagic strokes, but excluding transient ischemic attacks (TIA);
11. Confirmed or suspected diagnosis of infective endocarditis or other active infections;
12. There are diseases that significantly affect the evaluation of treatment, such as patients with neurological disorders that affect cognitive abilities, and patients with malignant tumors and an expected lifespan of no more than one year；
13. Other situations in which patients are not suitable to participate in this trial.