What changes do you think could occur?
Drawing blood isn’t going to change anything in your heart. MRI uses magnets to line up hydrogen atoms and radio waves and a computer to produce an image, how can that cause changes. The same holds true with your other tests. There is no mechanism for them to do any damage.
Your fears are irrational.
These type of fears are responsible for “so-called” anxiety and the cause of panic attacks.
You need to step back into reality and stop worrying about things that don’t pose any real danger. Life isn’t always a “walk in the park,” we all face hurdles in life but to be truly happy we have to face and accept them. I believe a psychologist could help you get rid of your irrational fears.
Wish you health and happiness,