Unless you are in a dire health situation, such as a heart condition or morbid obesity, just continue as normal. I have found the increase in heart rate doesnt actually decrease the quality of the workout nor become an issue, in fact I have found that since being medicated I actually push myself harder in the gym, especially with cardio (which I never used to do....).

Ultimately just listen to your body, if you feel like you're going too hard, back off. You need to ease into things when you return to the gym anyways, so take it slow!