IOWA CITY — Newcomer Pat Heiden, who raised and spent thousands more than two Johnson County supervisors in Tuesday’s Democratic primary, was poised to claim a seat on the board as she and incumbent Janelle Rettig handily beat incumbent Mike Carberry.Because no Republicans or Libertarians have filed for seats on the board, Rettig and Heiden likely will be elected in November, with terms lasting through 2022.Turnout surpassed 1994’s primary election record of 13,418, according to the Johnson County Auditor’s Office records.