Reassurance needed

Just when things are going smoothly a big fat spanner gets dropped in the works! Found out recently I have a kidney blockage. Could be a stone a tumour or a blood vessel pressing on the ureter. Having a nuclear renogram next week and the operation the following week. Have to stop the rivaroxaban 48 before the op. Saw the anesthetist yesterday about my pacemaker and atrial fibrillation. He is happy that I can have a general anaesthetic so that is reassuring. Still I am a bit scared as this will be my first operation since pacemaker was fitted. Just wondering if anyone here has been through similar. Thanks