Where are Biden's medical records?

Politico:

While John McCain’s past battles with skin cancer has received a great deal of scrutiny, Joe Biden’s near-fatal aneurysms in 1988 have yet to come under the spotlight.

Soon after ending his first presidential bid that year, Biden, who had been suffering from what he thought were headaches and a pinched nerve, collapsed in a hotel room shortly after giving a speech on foreign policy.

In his book "Promises to Keep," Biden says that he was unconscious for over four hours before he woke up in a hospital in Wilmington, Del. The senator was told that an artery was leaking blood into his brain and he was given his last rites by a priest. He was transferred to Walter Reed Medical Center where it was discovered that he had a second aneurysm on the other side of his brain.

Biden immediately underwent a four-and-a-half-hour operation to remove the leaking aneurysm. He had a second surgery in May to repair the other aneurysm and fully recovered after taking a seven-month leave from his seat as chairman of the Senate Judiciary Committee.

Following the memorial service of Rep. Stephanie Tubbs Jones, who died in August of an aneurysm, Biden said, “I know it sounds corny, it almost sounds maudlin, but you know, here she was one day walking around, just like I was the next day.

“I woke up four hours later on the floor with a hemorrhage. In her case, the same thing happened, only she never made it back.”

Dr. Anthony J. Caputy, chairman of the neurology department at George Washington University Hospital, said that after being treated for the aneurysms, Biden is “highly unlikely” to experience the problem again.

“Once they’re dealt with, they’re dealt with,” Caputy said. “The likelihood that he would ever have any trouble is very small, even smaller than the general population.”

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So where is it? If it is unlikely to happen again what is it that is making it hard to get his records released. Why didn't he do it when he was still running in the primaries?