Medtronic (NYSE:MDT) is preparing to float about $10 billion in bonds to help fund the $43 billion merger with Covidien (NYSE:COV), according to the Wall Street Journal, citing "people familiar with the sale."

Fridley, Minn.-based Medtronic originally planned to use some $13.5 billion in overseas cash in the Covidien buyout, scheduled to close early next year.

But new U.S. Treasury rules over so-called inversion deals pushed Medtronic to change its structure for the deal. The plan now is for the company to raise about $16 billion in external debt.

Medtronic executives are slated to meet with investors in person and via conference call starting as early as this week to discuss the bond sale, according to the newspaper. A company spokesman declined to comment on the size and timing of the bond sale, the Journal reported.

Medtronic has said it hopes to maintain its investment-grade credit rating once the Covidien acquisition closes. Both Standard & Poor’s Ratings Services and Moody’s Investor Service have said they plan to downgrade Medtronic based on the debt it’s taking on for the deal, but still plan to keep their ratings above junk-bond status.