Q. How is it possible to allow a surgery to take place where the patient is connected to a heart-lung machine? True, the body is receiving oxygenated blood. However, there is complete cessation of the natural heart and lungs. This is the traditional definition of death. Isn’t bringing about this cessation not killing the patient, at least halachically? Why are the relatives not Onenim? Why do they not have to tear Kri’a?

A. Horav Shlomo Miller Shlit’a explained that the fact that a person is immediately connected to supporting equipment such as the heart-lung machine does not constitute cessation of life, on the contrary it is done to extend the life of the patient.
The Rov pointed out that any medical surgery, where some significant blood vessels are cut, if not contained temporarily, it would cause the death of the patient by exsanguination. Yet no one questions that it is necessary and permitted.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a