Why pig-to-human heart transplant is for now only a last resort

Analysis: As doctors monitor world's first human recipient of pig heart, safety and ethical concerns remain

The world's first transplant of a genetically altered pig heart into an ailing human is a landmark for medical science, but the operation, and the approach more broadly, raise substantial safety and ethical concerns.

Surgeons at the University of Maryland Medical Center spent eight hours on Friday evening transplanting the heart from the pig into 57-year-old David Bennett, who had been in hospital for more than a month with terminal heart failure.