The 72-year-old Georgia Republican, who also is slowed by Parkinson's disease, came off a Capitol elevator in a wheelchair with Vice President Mike Pence at his side around 11:30 a.m. ET and headed to the floor where the two cast votes on the measure. The vote had been held open for a full hour so Isakson, who had just landed at Reagan National Airport after a flight from Atlanta, could make it.
Isakson's vote tied the tally at 50-50 and Pence the broke the tie.
Their votes were needed because two Republicans -- Susan Collins of Maine and Lisa Murkowski, who are each supporters of Planned Parenthood -- voted against it. Republicans have a 52-48 majority and all Democrats voted no.
The measure in question would repeal an Obama administration rule that was designed to prevent states from blocking Title X funding from going to health care providers that perform abortions. Republicans are using a special legislative tool called the Congressional Review Act to repeal several Obama-era rules and regulations issued at the end of President Barack Obama's term.
"Taxpayers should not be forced to subsidize the abortion industry in this country. Nor should they be forced to foot the bill for an organization like Planned Parenthood that has displayed such blatant regard for human life," said Sen. Joni Ernst, R-Iowa, and Rep. Diane Black, R-Tennessee, in a recent Washington Times op-ed explaining their legislation.
Democrats argued that allowing states to block funds for Planned Parenthood would hurt women who use the organization as a health care provider for things other than abortions.
"Allowing states to defund Planned Parenthood because politicians want to punish a health care provider only hurts women," said Sen. Dianne Feinstein, D-California. "The effect of this callous effort by congressional Republicans will be that fewer women get the health care they need. That's shameful."
Divisions over Planned Parenthood could also be a major sticking point in upcoming negotiations to fund the government, which is set to run out of money at the end of April.
Isakson spoke briefly with reporters after the vote.
"I'm in the fifth week of a 12-week rehab for my spinal surgery and I wanted to start getting my routines back. So I called and told them I'd be back this week and if I could vote, I'd like to vote," he said. "We didn't know at the time what it would be but it turned out to be the vice president's tiebreaker."
Isakson said he thought he'd be back this week to vote on the big Obamacare repeal bill that ended up not making it out of the House. Asked if he plans to vote for the "nuclear option" -- changing Senate requirements on confirming Supreme Court picks from 60 votes to 51 -- next week if Democrats carry out their threat to filibuster Neil Gorsuch, Isakson indicated he would.
"My option is always to be the team player. I'm on the team and I'll be doing what Mitch needs me to do," he said, referring to Senate Majority Leader Mitch McConnell who must decide if he will use the nuclear option.
Both Isakson and Pence are went back on the floor later Thursday afternoon when the CRA gets a vote on final passage and their votes will be needed again.