Heart rate going be over 130 on exertion causing me to feel unwell

[Westie2012]

I’ve had my cardiology appointment through for June 14th after my gp phone appointment where gp said he’d do an urgent letter to my cardiologist because of my symptoms and recent admissions to cardiac assessment after feeling really unwell when I was taking my daughter to school . I feel ok until my heart goes over 130 then I start to feel very strong palpitations, dizziness and get so out of breath which are the symptoms I was having before having my pacemaker . That’s happened twice now . I’m on 5mg bisoprolol which helped to keep my heart below 130 for a while . The nurse looking after me on one admission asked if I knew what my heart rate was when I was feeling unwell , when I said it was between 135:/150 she said for my age it could safely go up to 220 , I dread how I’d feel if it was that fast . Does anyone start to feel unwell if your heart goes over a certain rate ?