Walker was not only a trailblazer in the medical field; she was also a relentless visionary.
Or
Walker was not only a trailblazer in the medical field, she was also a relentless visionary.
Walker was not only a trailblazer in the medical field; she was also a relentless visionary.
Or
Walker was not only a trailblazer in the medical field, she was also a relentless visionary.