Houllier: Villa manager in hospital after being taken ill on Wednesday night
The Frenchman, who has been in charge at Villa Park since September, will remain in hospital for the time being and is hoping to be released soon.
Former Liverpool boss Houllier was forced to undergo life-saving emergency heart surgery in October 2001 after complaining of chest pains at half-time of the Anfield outfit's Premier League game with Leeds.
The 63-year-old made a fully recovery from an 11-hour procedure to repair an aortic dissection and returned to the dug-out in March 2002.
Houllier has endured a difficult campaign back in Premier League management with Villa sliding into a relegation battle, although recent victories over Newcastle and West Ham have seen the Midlands club reach the 40-point mark.
Villa are due to play host to Stoke at home in the Premier League on Saturday and it remains to be seen whether Houllier will be able to sit in the dugout for the weekend clash, with assistant boss Gary McAllister standing by.
The veteran tactician left Liverpool in May 2004 and had a two-year spell in charge of Ligue 1 outfit Lyon from 2005-2007 before taking a role with the French Football Federation prior to being tempted back into English football.