@hamidrezae81682 you can easily receive erroneous data from those leads. You are dealing with patients well being. At least you need to discuss this with your own biomed department, who need to verify this substitution. You are better of not getting an EKG than getting one that is wrong. That would be a disservice to the patient and dangerous. I understand that availability and price can play a role but should never, ever negatively impact real people. This could be the difference between a RBBB and a STEMI .
Where are you located and what make and model is your EKG machine? I am sure we can find some leads where I am.