The 30-year old collapsed to the ground and complained of dizziness during his sides 1 0 defeat. He was immediately withdrawn from the field and checked by medical staff who later diagnosed that he suffered inflammation of the heart muscles.
Last December, Blind was diagnosed with Myocarditis, a condition whose symptoms include shortness of breath, chest pains and an irregular heartbeat.
He was forced to undergo heart surgery in the Netherlands, and then was fitted with an implanted defibrillator, just under his skin, which causes electrical pulses to be sent to his heart, helping to regulate its rhythm.
After a two months absence, he was able to return to training and made his first appearance back for the team as a substitute towards the end of February. He went on to play two more Eredivisie matches, but then the Dutch league was shut down because of the Covid-19 pandemic.
Unlike many of their neighbours, it was not re-started but the final league standings were decided on a points-per-game basis making Ajax champions yet again.
As a consequence, Ajax had not played competitively since March, and the match against Hertha was an attempt to judge match fitness ahead of the new campaign. Ajax begin the 2020 2021 season away to Sparta Rotterdam on September 13th.
Following his latest scare though, Blind will now undergo further fitness tests before doctors decide whether it is safe for him to resume training with his colleagues once more.
Blind has previously spoken to the fact that he is not bothered by his condition and that the implant device is just there as a precaution and would only be needed in rare circumstances.
However, there will be concerns about rushing him back to soon, and Ajax will be mindful that they do not want Blind to become one of those (thankfully) rare people who has a heart attack on the pitch.
The last example in professional football came in March when Chineme Marans, who played in the Nigerian Premier League for Nasarawa United, collapsed and died during a league game.