On-X Heart Valve - 17mm Aortic and 23mm Mitral

The purpose of the study is to assess the safety and efficacy of the 17mm On-X Aortic
Prosthetic Heart Valve and the 23mm On-X Mitral Prosthetic Heart Valve when used to replace
diseased aortic or mitral valves in human subjects.

The On-X 17mm aortic valve will be implanted in approximately 20 and at least 15 patients who
will be followed for at least 1 year. Patients will be any age and will require this size
valve as determined in surgery but will be recruited prior to surgery based on results of
preoperative screening tests.

Enrollment into the 23mm mitral arm of the study has been terminated.

Inclusion Criteria:

1. Patients of any age; unless waived by local IRB assent of the patient and in all cases
consent of parent or legally authorized representative is required if a patient is
under the age of majority and not legally emancipated.

2. Patients who are sufficiently ill to warrant replacement of their diseased natural or
prosthetic valve, based on standard cardiovascular diagnostic workups.

3. Patients who are in sufficient satisfactory condition, based on the physical exam and
investigator's experience, to be an average or better operative risk, (i.e., likely to
survive one year postoperatively).

4. Patients who require an isolated aortic valve replacement size 17 mm or isolated
mitral valve replacement size 23mm.

5. Patients who are geographically stable and willing to return to the implanting center
for follow-up visits.

6. Patients or legally authorized representatives who are adequately informed of their
participation in the clinical study and what will be required of them in order to
comply with the protocol.

7. Patients requiring concomitant cardiovascular surgery, such as coronary bypass may be
included in the study.

Exclusion Criteria:

1. Patients who are pregnant, planning to become pregnant or are lactating. 2 Patients who
have a noncardiac progressive disease, which in the investigator's experience produces an
unacceptable increased risk to the patient.

3 Patients who have a documented history of substance (drug or alcohol) abuse or are prison
inmates.

4. Patients with a previous prosthetic valve, where it is not being replaced by a study
valve, or patients requiring multiple valve replacement.

5. Patients with active endocarditis or active myocarditis. 6 Patients who require
tricuspid or pulmonic valve replacement. 7. Patients who have not agreed to return for the
required number of follow-up visits or who are geographically unavailable for follow-up.

8. Patients who cannot be maintained on long-term anticoagulant therapy. 9. Patients with
non-cardiac illness resulting in a life expectancy of less than 1-year.

10. Patients previously enrolled and implanted in this trial may not re-enter after
withdrawal.

11. Patients already enrolled in another investigational device or drug study (nor can
enrolled patients be enrolled in other studies).

12. Patients with acute preoperative neurological deficit, myocardial infarction, or
cardiac event who have not returned to baseline for at least 30-days prior to enrollment.

13. Patients with aortic aneurysm or other medical condition that creates a higher than
usual risk of surgical complication.

14. Patients who are prisoners or mentally ill, and pediatric patients who are incapable of
understanding their assent as judged by the principal investigator.