The birth rate in Miami-Dade has dropped each year since 2007, according to the Florida Department of Health’s Bureau of Vital Statistics, from 34,286 births in 2007 to 30,479 births in 2012.

Another reason for the reduced number of heart surgeries, Harmon said, is the advent of medical technologies such as stents and balloon angioplasties that can be applied in an interventional catheterization laboratory at the center.

For instance, Harmon said, to repair a hole in the upper chambers of the heart, surgeons can now perform the great majority of those procedures — 90 percent — in a cath lab.

“Those used to be open heart procedures,’’ Harmon said.

Harmon estimated the center performs 30 to 50 interventional catheterizations per year that a decade ago would have required open heart surgery.

“This is where the field has gone,’’ he said. “It’s not unique to us. It’s the science of pediatric cardiology.’’

The pediatric cardiovascular program at Holtz is one of the oldest in Florida. It’s been approved as a CMS facility since the 1970s.

State regulators last visited the center in April 2012, and approved the facility for one year. A follow up visit was scheduled for June 4 for a three-year approval, but Burghart canceled the visit and voluntarily accepted probation in a letter to CMS dated April 25.

Matt Pinzur, a spokesman for Jackson Health System, which includes Holtz Children’s Hospital, wouldn’t talk about any strategy the hospital might have to increase the number of pediatric heart surgeries “because we are competing with local hospitals.”

Pinzur said that over the next year Jackson administrators plan to renovate labor and delivery rooms, postpartum rooms and other amenities in the hospital system’s obstetrics ward.

Burghart dismissed the significance of local competition from regional hospitals.

“We get patients from all across the state and internationally,’’ Burghart said. “It would be hard to say any one program has impacted us in any meaningful way.’’

But Holtz did lose a “young superstar” heart surgeon last year, Harman noted, a loss that might affect the volume of surgeries.

Hospital administrators feel strongly that probation in no way indicates a decline in the quality of care at the heart center.

“There’s been absolutely no impact on quality of care in the program,’’ Burghart said, noting that a committee of state regulators who visited the center in April 2012 gave the pediatric cardiology program high marks for the quality, teaching and research.

“This is one of the oldest programs in Florida, one of the original programs, and we have one of the largest training programs, if not the largest cardiac training program,’’ he said. “There’s an awful lot to be proud of, and we really don’t consider this a material issue.’’

Burghart said the Children’s Heart Center will meet the state required number of surgeries within 12 months.

“We evaluate thousands of children a year with all sorts of cardiac issues, from a child that had chest pain all the way through to the most complex of transplantations,’’ Harmon said. “The total program is evaluated with glowing results. The only issue was the volume of surgery.’’