Non-destructive evaluation techniques for prosthetic heart valves based on hologram interferometry. Part I.

The development of a technique applying hologram interferometry, which is a non-destructive, non-contact, full-field, highly sensitive method is reported. The valve under investigation is placed in a test chamber which has windows providing optical access. Deformations of the valve leaflets due to pressure loading are recorded by hologram interferometry. The resulting interferogram clearly indicates the existence of any defects or structural anomalies which may be present in the valve material. Three modifications to this technique, intended for qualitative and quantitative non-destructive valve screening tests are described. The proposed technique is expected to become an effective means of detecting hidden defects of replacement heart valves; it is thus considered as a prospective tool for quality control, particularly in the manufacture of bioprosthetic valves, where initial sites of late calcification and degeneration might be identified. The application of holographic non-destructive testing may therefore substantially improve the quality and durability of heart valve substitutes.