forced to scrub

I am a RN of 25 years and have spent the majority of my career in various operating rooms. I am experienced in General/Trauma/CVOR and while I can circulate all, I can also scrub many specialty services. At my current employer, I was hired with the understanding that I would only circulate CVOR, (CVOR is a distinctly different unit at my hospital and does not share personnel with General Surgery). However, whenever the department experiences a dip in the CVOR CST staffing numbers and have a need, they look to me to occasionally fill the void. I am adamant that I really, really dislike scrubbing hearts and when not done consistently, one really loses their 'edge' and is ill-prepared in the event of a true emergency. I feel that this is a 'bait and switch' ploy and while I'm a team player and happy to help out in other areas, I feel that this practice is not in the best interest of patients and certainly doesn't contribute to my job satisfaction. I have voiced my argument numerous times to management and it is forgotten for a while, but somehow always manages to resurface. What to do?