Mayo Clinic has named Dr. Richard Gray as the next chief executive for its operations in Arizona, which last year announced a significant expansion project.

Gray succeeds an interim CEO, who stepped in with the departure last year of Dr. Wyatt Decker, who is now chief executive of OptumHealth, the business within Minnetonka-based UnitedHealth Group that includes a growing network of ambulatory care centers.

Last year, Mayo Clinic said it would spend $648 million on an expansion of Mayo Clinic's hospital campus at the northern edge of the city of Phoenix. Mayo also has a campus in Scottsdale, which is a Phoenix suburb.

"Mayo Clinic is making a big investment on our Phoenix campus," Gray said in an interview. "Over the next five years, we'll be essentially doubling the size of our Phoenix campus. … We've been fairly space constrained in serving the southwester in terms of complex health care needs."

Mayo opened an outpatient clinic in Scottsdale in the late 1980s, and built the Phoenix hospital about a decade later. Gray first came to Mayo Clinic in Arizona in 1995 as a surgical intern and has spent most of his career at the Arizona facility.

Gray is scheduled to take the CEO job on May 13. He was co-chair for the implementation of a new electronic health record at Mayo.

Mayo's operations in the southwest U.S.. generated $1.37 billion in medical service revenue last year, according to a financial statement. Operations in the Midwest, including Mayo's headquarters in Rochester, generated $7.38 billion in medical service revenue.

The operating margins from the practice in Rochester and Arizona were comparable at about 10 percent last year.