Arizona Cardinals quarterbacks coach Freddie Kitchens underwent heart surgery Tuesday night.
The Cardinals confirmed the operation in a statement issued Wednesday in a tweet by Mark Dalton, the team's VP of media relations.
The surgery took approximately nine hours, and the next 24 hours are considered critical to Kitchens' recovery, a league source told ESPN NFL Insider Adam Schefter.
Kitchens, 38, began feeling dizzy and light-headed during Tuesday's practice before being taken to the hospital for the further testing. A CT scan performed at the hospital revealed a defect in Kitchens' aorta, which required immediate surgery at the Arizona Heart Institute.
The team gathered for a prayer for Kitchens' recovery prior to the start of Wednesday's OTA session.
Coach Bruce Arians told The Arizona Republic that Tuesday night was "pretty scary."
Arians said Kitchens tried to "gut out" Tuesday's practice but the quarterbacks called to the team trainer, who insisted Kitchens go into the locker room.
Arians said Kitchens was "not out of the woods" yet, but had cracked a joke in the hospital after the surgery.
Kitchens, a former quarterback at the University of Alabama, has worked on the Cardinals' coaching staff since 2007.
Information from The Associated Press was used in this report.