The Dutchman completed his move from Valencia to Sevilla earlier this summer, but his career could now be in danger due to medical complications
The heart abnormality was not detected during the Dutchman's routine medical checks earlier this summer, but came to light during extra tests.
Maduro will now be further examined this week to determine the exact extent of his heart issue.
"I only know that it's not life-threatening. It is a congenital abnormality rather than cardiac arrhythmia. I hope to know more by the end of the week. I'll just have to wait for now," commented Maduro.
The Spanish side will schedule a press conference once they have more information about the Dutchman's condition.
The 27-year-old only recently joined Sevilla from Valencia on a Bosman free transfer, and has yet to make his first official appearance for the club.