MINNEAPOLIS -- Minnesota Vikings defensive end Everson Griffen underwent a heart-related test this week after being deactivated from Sunday’s game against the Kansas City Chiefs, but a league source said the test was “precautionary” and was given to make sure Griffen was ready to return.

The defensive end, who leads the team with three sacks this season, was not on the Vikings’ final injury report last week, but was declared inactive on Sunday morning because of illness, the Vikings said. A league source said Griffen hasn’t dealt with heart-related issues before, and did not have an irregular heartbeat.

Griffen did not practice on Wednesday, but was at the team facility and is expected to be a full participant on Thursday.

"He’s finishing up some tests today," coach Mike Zimmer said Wednesday. "We anticipate that everything will finish good."

Zimmer said Sunday he found out about Griffen between 9:30 and 10:00 Central time. When asked Monday about a Pro Football Talk report that the NFL would look into why the Vikings didn't announce Griffen's injury before Sunday's deadline to declare inactives at 10:30 Central, Zimmer said, "I don’t know anything about the NFL investigating. All I know is the guy was sick because I saw him." Zimmer added Griffen seemed to be in good spirits on Monday.

In the first season of a five-year, $42.5 million deal, Griffen posted 12 sacks in 2014 and was named an alternate for the Pro Bowl. He blossomed in his first year with Zimmer after four seasons as a part-time player, and was voted one of the Vikings' captains by teammates this season.