Masimo Corp. Chief Executive Joe Kiani co-led a $24 million equity investment in Stereotaxis Inc. that could be worth as much as $50 million.

Irvine-based Masimo makes patient monitoring equipment. St. Louis-based Stereotaxis makes robotic devices to treat cardiac arrhythmia.

Kiani made the investment on a personal basis.

Stereotaxis gets $24 million upfront in exchange for preferred stock with a conversion price of 65 cents, a 10% premium on Sterotaxis’ share price at the time. Shares traded recently at 84 cents for a $19 million market cap.

It will use part of the initial money to retire $13 million in debt.

Stereotaxis could receive up to about $26 million more on the exercise of the warrants.

Kiani and DAFNA Capital Management LLC in Los Angeles co-led the investment, with participation by at least six other investors, a news report said.

Kiani in August participated in a $13 million Series A investment in Bioniz Therapeutics Inc. in Irvine, a deal co-led by former Allergan Inc. Chief Executive David Pyott. Bioniz develops cancer-fighting drugs.

Kiani will join the Stereotaxis board.