Magna Mitral - 23mm

Inclusion Criteria: 1. Patient has mitral valve disease requiring surgical replacement 2. Patient has provided written informed consent prior to mitral valve surgery 3. Patient is expected to survive surgery and be discharged 4. Patient is willing to comply with specified follow-up evaluations 5. Patient is 13 years of age or older Exclusion Criteria: 1. Patient has life expectancy \< 12 months due to non-cardiac co-morbid conditions; 2. Patient has/had active endocarditis within the last 3 months 3. Patient requires replacement of a native or previously implanted prosthetic, tricuspid, pulmonic or aortic valve; 4. Patient was previously enrolled and implanted in the study 5. Patient has/had prior aortic, tricuspid and/ or pulmonary valve surgery, which included implantation of a bioprosthetic valve or mechanical valve that will remain in situ 6. Patient has a body surface area (BSA) \> 1.9m2 7. Female patients who are pregnant, planning to become pregnant, or lactating 8. Patient has a documented history of substance ( drug or alcohol) abuse 9. Patient is currently a prison inmate 10. Patient is currently participating in an investigational drug or another device study 11. Patient is undergoing renal dialysis for chronic renal failure or has hyperparathyroidism 12. Patient has active myocarditis 13. Patient has had an acute preoperative neurological deficit, myocardial infarction, or cardiac event and has not returned to baseline or stabilized \> 30 days prior to the planned v alve implant surgery 14. Patient has an abnormality such as an aortic aneurysm (e.g. due to cystic medial necrosis or Marfan's syndrome), aortic dissection, or ventricular aneurysm that might place