While occupying a Europe-wide role, Bartling effectively succeeds Tonic Life's UK MD Tamsin Tierney, who left for a role at Cohn & Wolfe earlier this year.
Bartling joined Edelman in 2003, initially in Chicago, before moving to London in 2010 and taking the helm of its UK healthcare team in January 2014, before departing in October last year.
She began at Tonic Life Communications, one of Huntsworth's healthcare specialist firms, on Tuesday (5 September). She reports to global CEO Maryellen Royle, who was promoted to her US-based role in October.
Tonic has "dual headquarters" in the US (Philadelphia) and UK (London).
Bartling said: "I am thrilled to join the Tonic team and look forward to building an expanded offering and presence in Europe. Tonic has a great heritage in Europe and expertise in bringing strategic and creative solutions to health clients."
Neil Matheson, who was the boss of Huntsworth's health division, which has grown to become its biggest revenue earner, left his role suddenly in July.