Adding to the defence
The Dutchman has been a fan favourite at the Stadium of Light since his move from Chelsea back in 2014, and is one of the three league scorers for the struggling Black Cats this season managing three goals for David Moyes' side.
There had been rumours of a possible exit from Wearside, the 26-year-old handed in a transfer request and chief executive Martin Bain stated the Dutchman's desire to leave.
"If a player openly states he does not want to play for our club," Bain told Sky Sports. "It is clear that we have a decision to make."
"In this instance and in regard to this particular player," he stated. "We have done what we feel is right for Sunderland, which will always be our priority."
A inital £9m fee has been agreed and Van Aanholt is expected to complete his medical at Palace on Friday, and will follow on from former Leicester City man Jeffrey Schlupp to take their January spending to £27m.
"Patrick van Aanholt is having a medical today," Sam Allardyce confirmed. "It won’t go through until every aspect of negotiation, and what the medical might say (has been done)."
"It’s in the process at the moment," he stated. "I wouldn’t imagine (the heart issue) will be a problem."
"I’m sure the medical will be okay," Allardyce added. "He will be looking forward to joining us."
A great talent
Van Aanholt will reunite with his former manager Allardyce, who managed him during Sunderland's excellent survival push in the final half of last season.
The Dutchman was pivotal in that eventual survival, and Allardyce stated that he will be looking to working with the full-back once again.
"He was a major saviour in our run last season," he said. "He was a major part of that success story."
"His contribution, in terms of assists and goals, was massive," the coach stated. "When it came to defending he got better with me and listened to what we told him about."
"Where the weaker side of his game was and he made it stronger," the former Sunderland man admitted. "Great energy, a very good player."
"He and Schluppy will increase the speed and energy levels of the squad," he stressed. "If everything goes well, I look forward to him joining me again here."
"I have to get the maximum out of his talent," Allardyce concluded. "Because he is a great talent."
Crystal Palace will take on Manchester City in the fourth round of the FA Cup at Selhurst Park on Saturday, January 28 with kick-off at 3pm GMT.