When does the interventricular foramen of heart close?

The interventricular foramen, also known as the foramen of Munro, is not a feature of the heart but rather a passageway in the brain that connects the lateral ventricles to the third ventricle. In the context of the heart, you might be referring to the foramen ovale, which closes shortly after birth as the pressure in the left atrium increases, typically within the first few days to weeks of life. This closure helps to establish normal postnatal circulation. If you meant a different structure, please clarify!