What is the ruling on heart transplantation and transplanting parts of a pig into a human?

It is permissible to transplant a heart if success of the operation is highly probable, and if it is not taken from an animal, and its owner gave permission before his death, or his heirs after his death, or the guardian of the Muslims if the deceased has no heir. It is not permissible to transplant parts from a pig except in cases of dire necessity and the absence of a pure alternative.