By that logic, any life-preserving medication or intervention would be wrong. Removing an inflamed appendix or administering CPR are just as much intervening in a process that would lead to death as transplanting a heart. Even yanking someone out of the path of an oncoming bus could be interpreted as saving someone who was being called by God.
Not only does the Church accept the transplanting of human organs, it recognizes the donation of organs and blood to those in need as acts of charity and therefore commendable. Needless to say, such donations must not in the slightest way cause the death of the donor.