In an operation more difficult than doctors had expected, Jack C. Burcham, a retired railroad engineer from LeRoy, Ill., today became the world's fifth -- and oldest -- recipient of a permanent artificial heart.

The six-hour surgery was extended by more than two hours when surgeons discovered that Burcham's chest cavity was smaller than sophisticated X-rays had indicated.

Guidelines for the experimental procedure specify that patients must weigh at least 150 pounds, to ensure that the Jarvik-7 heart will fit in the chest. Burcham weighs 163 pounds, but the contour of his breastbone would have pressed it against the polyurethane-and-metal heart, said Dr. Allan Lansing, spokesman for Humana Heart Institute International.

Surgeons solved the problem by removing a small piece of Burcham's breastbone and surrounding cartilage and by repositioning the heart to get it to fit. The extra maneuvering put strain on the needle holes where the device was sewn in, causing moderate bleeding.

Burcham was monitored in the operating room an extra two hours to make sure the bleeding would subside. Both of Humana Hospital Audubon's previous artificial-heart recipients developed internal bleeding after their operations and had to have further surgery.

Lansing described the unexpected problem as an "aggravation, a nuisance," adding that "there was never any thought that it would not go in."

Burcham, 62, was vigorous and apparently healthy until a sudden heart attack last October nearly killed him. Before surgery today he could walk only a few steps at a time and required being on an oxygen tank continuously, Lansing said.

Burcham's overall physical condition is described as "comparable" to that of the other two men who received artificial hearts here, William J. Schroeder and Murray P. Haydon. Schroeder and Haydon were expected to live only days or weeks without an artificial heart, but Burcham might have lived for up to two months, although he would have been bedridden, Lansing said.

Burcham had neither the extreme weight loss Haydon experienced before surgery nor the scarring from previous chest surgery that complicated Schroeder's recovery. And unlike the first Jarvik-7 recipient, Barney B. Clark, who died of multiple organ failure after 112 days, Burcham has no longstanding respiratory problems.

Burcham's kidneys, however, are in far worse shape than those of the others -- so bad, in fact, that Burcham may have to undergo dialysis, Lansing said. All the previous recipients have had temporary kidney problems after surgery, which improved as their circulation increased. Burcham's heart attack was caused by coronary artery disease, which narrows the blood vessels that nourish the heart. Burcham, an avid gardener and woodworker, was working on the roof of his house at the time of his heart attack, but managed to climb down and telephone an ambulance.

Burcham's heart disease may increase the likelihood of a stroke, a major risk with the artificial heart, because it suggests that blood vessels leading to the brain also may be narrowed by plaque. A fragment of that fatty buildup could break free and lodge in the brain, causing a stroke like the one Schroeder suffered in December, following implant surgery Nov. 25. Initial tests indicate that arteries in Burcham's head and neck are not narrowed, Lansing said.

Because a stroke also could be caused by blood clots, doctors have been adjusting the dosage of anticoagulants given artificial-heart patients. As a result of Schroeder's stroke, they gave larger doses to Haydon, whose heart was implanted Feb. 17. But because Haydon has been dogged by intermittent internal bleeding that has led to breathing difficulties, Burcham may get "a trifle less" blood-thinning medication than Haydon, Lansing said.

Burcham was an Illinois Central Gulf railroad engineer for 30 years between Bloomington, Ill., and St. Louis. He was an Army paratrooper in World War II.

Burcham and his wife, LaVonne, have been married 42 years and have four grown children. Before his illness, he ran a construction company with his two sons. He has been miserable and frustrated at his sudden weakness and exhaustion, his doctors said.

"His goals are to be up and around, to be ambulatory, to be able to walk and to get back in his woodworking shop," Lansing said.

Burcham's implant is the third at Humana Hospital Audubon in five months.

Dr. William C. DeVries, who performed all three, has federal approval to perform three more before the series is reviewed to determine whether further implants should be allowed.

Last week, Schroeder became the first artificial-heart recipient to be discharged from a hospital. On Saturday, Schroeder made house calls to his doctors, being driven in a van to visit the homes of DeVries and Lansing.

[In Stockholm, Leif Stenberg, 53, the first European recipient of a permanent artificial heart, continued his steady recovery from a 10-hour operation a week earlier, the Associated Press reported.]