The heart patient was in an intensive care unit fighting for his life. A doctor walked in and started talking to the patient. Suddenly, he began beating the patient viciously.
The patient, a 45-year-old man, died soon afterwards, but it is not known whether he died of the beating, Mail Online reported.
The beating was recorded on camera, and Dr Andrey Votyakov, a highly-regarded Russian anaesthesiologist who had an unblemished record, is being investigated by authorities.
The incident happened soon after the patient underwent surgery at a hospital in Perm, in the Urals.
The doctor told investigators that he was tired after a 36-hour shift and grew angry when the patient started abusing him, Sky News reported.
Said Dr Votyakov: "As soon as I came into the room with my team, he started to call me various derogative names. And I just got blown away by it.
"We had spent so much time with his very complicated case to help him recover, and he said not a single word of gratitude.
"And then the chronic tiredness added to it. I got carried away, and I punched him several times."
The attack happened early this year, but the footage was made available only recently, the report said. The footage does not show any other doctors or nurses seeking to intervene.
'I am very sorry'
'I am very sorry'
Said the doctor: "We continued the treatment after the incident, but sadly the patient died. I am very sorry for what happened, and I want to apologise to the patient's family."
Dr Votyakov's boss said the "violent" staff will be sacked.
A police spokesman in Perm said: "We saw the video which went on YouTube. We are investigating it and checking the details of what happened."
Senior investigators have already visited the hospital and quizzed staff, seeking to understand if the beatings were the direct cause of death. They were also "checking if the medical help after the attack was given on the highest level".
It is not clear what charges the doctor may face.
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