The wife of NASCAR driver Tyler Reddick on Sunday said the couple's 4-month-old son is in the cardiovascular intensive care unit at a North Carolina hospital.
Alexa Reddick posted to social media that doctors are working on improving the "heart function" of Rookie, the couple's second son who was born in May.
She wrote she had been seeking medical care for Rookie for some time without getting any concrete answers for what appeared to be "signs of heart failure that were being missed."
"Always trust your mom gut," she added.
Tyler Reddick, who has not discussed his son's heath battle, finished seventh in Sunday's race at Kansas Speedway.
The Associated Press contributed to this report.