The 64-year-old went to hospital on Tuesday night to undergo tests and will now have an operation on a minor blockage in one of his arteries, Press Association Sport understands.
Tottenham confirmed on Tuesday night that the former West Ham manager was set to undergo a "medical procedure" that would rule him out of the club's trip to Rubin Kazan this week. Assistant manager Kevin Bond and first-team coach Joe Jordan will take charge of the team for Thursday night's Europa League match in Russia.
Source: PA
Source: PA