"Daley Blind has been diagnosed with myocarditis," a statement read as quoted by ESPNFC.
"In the last few days, the centre-back has been the subject of thorough medical investigation after experiencing a short episode of vertigo during the match between Ajax and Valencia. It was decided to preventively place a subcutaneous implantable defibrillator -- a device that is inserted under the skin -- as a consequence of the procedure, which took place yesterday," it added.
The club further said the former Manchester United player would miss their January training camp in Qatar.
"The most important thing is that I'm feeling good at the moment and trying to come back as soon as possible," Blind was quoted as saying by ESPNFC.
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