What is forbidden in Jehovah Witness?
Jehovah's Witnesses believe that a human must not sustain his life with another creature's blood, and they recognize no distinction "between taking blood into the mouth and taking it into the blood vessels." It is their deep-seated religious conviction that Jehovah will turn his back on anyone who receives blood …
This is based on an interpretation of passages in the Bible that prohibit consumption of blood. However, Jehovah's Witnesses do not object to medical or surgical treatments in general, only to the use of blood products.
Jehovah's Witnesses accept medial and surgical treatment. They do not adhere to so-called “faith healing” and are not opposed to the practice of medicine.
Open heart surgery using cardiopulmonary bypass has not been used for Jehovah's Witnesses because of their religious convictions and a church law forbidding blood transfusion. Development of bypass technics which utilize only blood substitutes for priming have made such procedures acceptable to these patients.