See your GP who should be able to give you a cardiogram at the surgery. He may also ask for an ultrasound of the heart. If he is concerned, he will bring in a heart specialist to monitor you. When my heart rate went to 170 I went to the ER. It seems my heart has made up a second electrical impulse and I have two heart beats now. I take meds to keep one at bay. I have no high blood pressure and never really have had. Just rapid beats since chemo and AI.
Oncology is to give you chemo and stop the cancer. That is their focus and they will try different drugs to trick your body into accepting the chemo. Apart from checking blood pressure, they don't investigate heart problems.