Heather Tietjen, CNP started with Avera Medical Group Dell Rapids and Avera Dells Area Hospital on Monday, November 8. (Photo/Tammy Chamley) Tammy Chamley | Editor Heather Tietjen, CNP, has joined the Avera Dells Area Hospital and Avera Medical Group Dell Rapids. Her first day was Monday, November 8. A nurse practitioner is an advanced practice…