Valley Regional Hospital and Dartmouth Health have signed a letter of intent to affiliate, the two institutions announced on Wednesday. If the affiliation is approved, Valley Regional would join the ranks of other small Upper Valley hospitals that in the past decade have become part of the DH health care behemoth. "We believe that collaboration among providers is the most effective way to deliver that care. To that end, Valley Regional and Dartmouth Health have signed a letter of intent to begin the process of strengthening our relationship by having Valley Regional Hospital become part of the Dartmouth Health system," according to a statement posted on Valley Regional's website.