Four years ago his doctors at the University of Oklahoma implanted on the outside of his heart an experimental device that measures fluid pressure in the organ.

FORBES: Magazine Article

Most nations have instead adopted highly regulated donation systems like the United Network of Organ Sharing in the U.S. UNOS monitors each kidney, lung, heart or liver available from a deceased donor going to a patient on a wait list.

FORBES: On The Cover/Top Stories

The heart is an organ that can give quantitative data of quality.

BBC: Stem cell trial halted

But being a heart transplant patient comes with the extra challenge of getting the organ to beat at an acceptable rate.

CNN: Heart transplant patients push physical limits at Ironman

This is when the heart is the quietest, so it's easiest to get a good image of the organ.

CNN: Heart test can pack radioactive wallop

And he doesn't dwell on what the episode might mean to U.S. residents on the donor-organ waiting list or to foreigners applying for legal immigration who might have congestive heart failure and dream of treatment in America.

WSJ: Book Review: Twelve Patients