Using zero ohm patient cable instead of ten ohm

I would presume: increased signal to noise ratio (bad), and a significant lack of over current protection (which could damage input gates) These devices are amplifying tiny signals, so they don't have much protection. 10 ohm in the leads at 1v is a max of 100mA, Microcontrollers (which are not ECG machines) don't like to see more than circa 60mA at sensor inputs.

Replacing these leads with the correct type will run a cost around $50-$100. If you are using these in any type of health capacity, and you have a liability insurance policy in place, you might want to check if using incorrect leads will alter your insurance coverage.

@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.