Russell Marion Nelson is the 17th president and prophet of The Church of Jesus Christ of Latter-day Saints (LDS Church). Prior to his service as head of the Church, President Nelson served as president of the Quorum of the Twelve Apostles. He is also a retired American physician and cardiothoracic surgeon.

A native of Salt Lake City, Utah, Nelson received his B.A. and M.D. degrees from the University of Utah (1945, 1947). He is a member of honorary scholastic societies Phi Beta Kappa and Alpha Omega Alpha. He served his residency in surgery at Mass. General Hosptial in Boston and at the University of Minnesota, where he was awarded his Ph.D. degree in 1954. Shortly after medical school, he began working with the team of doctors which created the first heart-lung machine. In 1951, the machine was used in the first open-heart operation on a human being. Four years later, Nelson was the first doctor in Utah to perform successful open-heart surgery using a heart-lung machine.

Nelson served a two-year term of medical duty in the U.S. Army during the Korean War, being stationed in Korea, Japan, and at Walter Reed Army Medical Center in Washington, D.C. Later he worked for a year at Massachusetts General Hospital in Boston, Massachusetts.

Nelson returned to Salt Lake City in 1955 and was initially on the academic staff of the College of Medicine at the University of Utah, where in November of that year he performed the first cardiac operation in Utah utilizing cardiopulmonary bypass. That operation was performed at the Salt Lake General Hospital (SLGH) on an adult with an atrial septa defect.

In March 1956, Nelson performed the first successful pediatric cardiac operation at the SLGH, a total repair of tetralogy of Fallot in a four-year-old girl. In 1959, he joined the staff of the Salt Lake Clinic, became associated with the LDS Hospital, and continued to make major contributions to the development of the thoracic specialty both in the clinical sciences and as the second director of the residency program.

Nelson's surgical volume was sufficiently large that it was a critical component of the residents' experience. He was an innovative and facile surgeon responsible for many improvements in cardiac operations. He also established a research laboratory at LDS Hospital.

By the late 1960s, Nelson's experience with artificial aortic valve implantation was such that he was able to report a large series of patients with an exceptionally low operative mortality.

In a unique combination of spiritual and professional obligations, Nelson performed heart surgery on LDS Church president Spencer W. Kimball.