This part of ISO 5840 is applicable to heart valve substitutes intended for implantation and provides general requirements. Subsequent parts of the ISO 5840 series provide specific requirements. ISO 5840 is applicable to: newly developed and modified heart valve substitutes; the accessory devices, packaging, and labelling required for their implantation; and for determining the appropriate size of the heart valve substitute to be implanted. ISO 5840 outlines an approach for verifying/validating the design and manufacture of a heart valve substitute through risk management. The selection of appropriate qualification tests and methods are derived from the risk assessment. The tests may include those to assess the physical, chemical, biological, and mechanical properties of heart valve substitutes and of their materials and components. The tests can also include those for preclinical in vivo evaluation and clinical evaluation of the finished heart valve substitute. ISO 5840 defines operational conditions for heart valve substitutes. ISO 5840 does not provide requirements specific to homografts, tissue engineered heart valves (e.g. valves intended to regenerate in vivo), and heart valve substitutes designed for implantation in circulatory support devices. NOTE: A rationale for the provisions of ISO 5840 is given in Annex A.