If a person takes a beta blocker for a heart arrhythmia (bisoprolol) can they have Juvederm Ultra 4?

Good question. Always better to ask questions and be safe than sorry.
Good news, you should have no problems. The anesthetic is so localized and in such small quantity that it will not interfere.
That being said, be sure your provider is aware of your medical conditions and all medications you're taking. Your provider will keep you well within a safe zone. 
Be sure a "physician" is on your case. My greater concern would be more in regard to the anticoagulants you're likely on. Depending on the anticoagulant medication, I would like you to be off them for a couple to few days prior to injecting the filler due to bleeding and bruising concerns. 
I also may want to get the blessing of your cardiologist to take you off them for a short period. It's generally not a big deal, but 1) always better to be on the safe side, 2) better assures a good outcome absent unnecessary bruising, and 3) why risk anything when there's not a need or compelling reason.
Wishing you a wonderful outcome!
Warmly,
Arbella Sarkis, MD

Thankyou for your question.You do not need to worry about an interaction between the beta blocker and filler . The local anesthetic in the filler is just that locally spread. Enjoy!