This study will evaluate the safety and performance of the ADAPT 3D - ALR in adult patients requiring replacement of aortic valve. 15 patients in one site in Belgium will all be treated with ADAPT 3D - ALR.

The purpose of this study is to conduct the initial clinical investigation of single piece ADAPT treated 3D - ALR (Aortic Leaflet Repair) to collect evidence on the device's safety and performance. The study is anticipated to confirm successful clinical safety and clinical performance with significant improvements in clinical hemodynamic performance.

The ADAPT® technology is used to process animal derived tissues to produce implantable tissue prosthetic devices that are compatible with the human body. This technology has been shown to produce reliable, biocompatible and versatile regenerative prosthetic devices capable of being used instead of synthetic products currently used in many soft tissue repair applications.

15 patients with aortic valve insufficiency or stenosis will be enrolled in this single arm single site study.

Follow-up will continue through to 26 weeks.

Inclusion Criteria:

1. Patient is older than 18 years of age and ≤ 85 years.
2. The subject's aortic annular measurements are ≥ 21 mm to < 27mm as confirmed on pre-op echo.
3. The subject is a candidate for Aortic Valve Replacement.
4. The subject has documented moderate or severe Aortic Stenosis and/or Aortic Insufficiency (defined as grade 2, 3 or 4).
5. The subject is willing and able to comply with specified follow-up requirements and evaluations, including transesophageal echocardiography (TEE) if there are inadequate images by transthoracic echocardiography (TTE) to assess the aortic valve.
6. Patient has signed the informed consent

Exclusion Criteria:

1. All patients who require emergency surgery (within 24 hours of a presentation to an emergency department) for any reason.
2. Subject with a pre-existing valve prosthesis in the aortic position.
3. Patients requiring repair of other cardiac valves will be excluded.
4. Subject with active endocarditis.
5. Heavily calcified aortic roots or "porcelain aortas".
6. Leukopenia with a WBC (white Blood Cells) of less than 3000.
7. Acute anaemia with a haemoglobin less than 8 g/dL.
8. Platelet count less than 100,000 platelets/microliter, and if less than 150,000 platelets/microliter, platelet reduction of >10,000 platelets/microliter per day over two consecutive days (Note: Where a platelet count is less than 150,000 platelets/microliter but greater than 100,000 platelets/microliter, platelet count testing is to be conducted over 2 consecutive days. If platelets are reducing over those two consecutive days, the rate of reduction in platelets must be less than 10,000 platelets/microliter per day, otherwise the participant must be excluded).
9. History of a defined bleeding diathesis or coagulopathy or the subject refuses blood transfusions.
10. Active infection requiring antibiotic therapy (if temporary illness, subjects may enroll 2-4 weeks after discontinuation of antibiotics).
11. Subjects in whom transesophageal echocardiography (TEE) is contraindicated.
12. Low EF < 50 %.
13. Life expectancy < 1 year, or severe comorbidities, such as cancer, dialysis, or severe COPD.
14. The subject is an illicit drug user, alcohol abuser, prisoner, institutionalised, or is unable to give informed consent.
15. The subject is pregnant or lactating (non-pregnancy to be confirmed by pregnancy test for all child bearing potential females).
16. Recent (within 6 months) cerebrovascular accident (CVA) or a transient ischemic attack (TIA).
17. Myocardial Infarction (MI) within one month of trial inclusion.
18. Currently participating in, or have been recently exited from (within 30 days of enrollment in this study), or plan to be enrolled in another clinical