Effects of long term device-guided slow breathing on sympathetic nervous activity in hypertensive patients: a randomized open-label clinical trial oleh Silvana de Barros, Giovanio Vieira da Silva, Josiane Lima de Gusmão, Tatiana Goveia de Araújo, Dinoélia Rosa de Souza, Crivaldo Gomes Cardoso, Bruna Oneda, Décio Mion