Fairfax Hospital became the first hospital in the Washington area yesterday to win approval to transplant human hearts.

An official said the facility, which had enlisted heart transplant pioneer Dr. Christiaan N. Barnard to lobby for the program, is ready to perform the operation "immediately."

Virginia Health Commissioner James B. Kenley approved the hospital's application despite the strong opposition of health planners at the Northern Virginia Health Systems Agency. The planners and federal officials contend that there are too many transplant centers around the country and urge that their proliferation be checked.

"The decision is absurd," said an aide to Sen. Albert Gore Jr. (D-Tenn.), author of the National Organ Transplantation Act. "You're not going to find a medical expert in this country who's looked at this thing and agrees. We have maybe twice as many heart transplant programs as we need."

Officials at Fairfax Hospital, the largest hospital in Northern Virginia, said that the approval represents a new level of prestige for the 25-year-old, 656-bed hospital. "No longer do heart patients have to travel out of the area for most sophisticated medical services," said hospital administrator Everett M. Devaney. "We're ready immediately."

The hospitals nearest Washington that offer heart transplants are Johns Hopkins in Baltimore, which performs heart, lung and kidney transplants, and the Medical College of Virginia in Richmond, which also transplants livers and kidneys.

Although it has a highly regarded open-heart-surgery program, Fairfax Hospital has not performed transplants. Critics of the hospital's proposal had argued that experience with immunosuppressant drugs, which reduce the chances of organ rejection, was a minimum requirement for facilities seeking to perform heart transplants.

Also, opponents of the hospital's application warned that Fairfax would be forced to compete with the transplant programs in Richmond and Baltimore for scarce heart donors.

The result, these critics say, will be a small number of transplants at Fairfax and a reduction in transplants performed at Johns Hopkins and Medical College of Virginia. Health planners say that death rates are higher for transplant patients at centers that perform relatively few transplant operations and that Fairfax's program could harm the nearby programs.

John Hopkins and the Medical College of Virginia, which are regarded as among the finest heart transplant centers in the country, are below capacity. Initially, both opposed Fairfax's application for a certificate of public need to perform transplants, although Medical College of Virginia later said it had reached an understanding with Fairfax.

Virginia Health Commissioner Kenley dismissed concerns that the Fairfax program would degrade transplant services in Baltimore or Richmond.

The "project will promote continuity of care for those Northern Virginia residents who already use Fairfax Hospital," he said. It "represents a logical extension of the existing cardiac treatment program of the Fairfax Hospital."

Fairfax Hospital had argued, in essence, that it should be allowed to perform the transplants because it had the ability to do so. That was also the thrust of the argument advanced by Barnard, who performed the first heart transplant in 1967, when he testified in Richmond on the hospital's behalf last month. Barnard said transplant technology is so advanced that every hospital with a proficient heart surgery program should be able to perform heart transplants.

That approach, critics say, undercuts rational apportioning of medical resources. "It represents a defeat for health planning, and to some extent a victory for the unnecessary proliferation of services," said George L. Barker, associate director of the Northern Virginia Health Systems Agency. "We think it's a mistake."

The District's Washington Hospital Center has also filed an application with health authorities for a heart transplant center. A decision is expected this year.

In its application, Fairfax Hospital said it planned to obtain donor hearts from two sources: trauma patients who die in the emergency room and an organ-sharing network.