John T. Shepherd, a cardiovascular physician whose breakthrough pathways for managing high blood pressure and whose understanding of space science enabled scientists to endure space travel, is no more.

Shepherd, who was a visionary, scientist and cardiologist at the Mayo Clinic, also headed the American Heart Association, served as a NASA adviser and led U.S. scientific exchanges with the Soviet Union during the Cold War, died last Tuesday. He was 92.

Shepherd's research caught the attention of the U.S. space program, which was struggling with the problem of astronauts fainting upon returning to Earth and suffering from reduced bone mass and atrophied muscles due to weightlessness.

Shepherd, working with counterparts in the then-Soviet Union, came up with some countermeasures ... exercise protocols (still) used in outer space, and fluid-loading and salt-loading that have been quite helpful, said Dr. Michael Joyner, associate dean for research at Mayo Clinic in Rochester, Minn.

According to an official statement, Joyner said that Shepherd was one of the top cardiovascular researchers of the past half-century. Shepherd's revelation on how the nervous system, and not just the kidneys, was vital to blood pressure regulation changed the manner in which cardiovascular diagnosis was initiated.

He made fundamental observations about how the nerves control blood pressure, and that has led to all kinds of ideas and therapies for hypertension, Joyner said.

Some of the devices that can be attributed to John Shepherd are pacemaker-like devices under development that help regulate malfunctioning baroreceptors in the neck. This in turn helps the brain interpret the body's blood pressure, but can get out of whack like a broken thermostat that keeps turning up the heat, Joyner added.

Dr. Shepherd was a giant in cardiovascular physiology who made fundamental observations about blood pressure regulation in humans and many other elements of cardiovascular control, said Joyner.

He was also a visionary leader who engaged in and promoted translational research 30 or 40 years before it was a buzz word at NIH (National Institutes of Health) and in the scientific community, added Joyner.

Some of Shepherd's research findings in the 1950s, 1960s, and 1970s are only now bearing fruit as the technology catches up, Joyner said.

Shepherd was born May 21, 1919, in Belfast, Northern Ireland, and received his M.B., B.Ch, M.Chir and M.D. with honors from Queens University in Belfast. He completed his internship and residency at the Royal Victoria Hospital in Belfast.

Shepherd received many awards over the years, including honorary degrees from the Universities of Bologna, Ghent and Queens. He was actively involved with NASA and the National Academy of Sciences, and chaired the academy's Committee on Space Medicine from 1965-74.

During the Cold War, Shepherd helped the U.S. space program by working with colleagues in the then-Soviet Union on space physiology.

As Shepherd performed cutting-edge scientific work, he also led the ongoing transformation of Mayo Clinic from a group practice to a group practice embedded in a world class academic medical centre.