Experts assisting surgeons in a robotic heart operation on a man who later died left the theatre early, an inquest has heard.
Stephen Pettitt, 69, suffered multiple organ failure and died days after the procedure at the Freeman Hospital in Newcastle in March 2015.
The inquest heard the lead surgeon had declined training in the use of the advanced Da Vinci robot.
An investigation was launched by police and health bosses after the death.
The procedure was led by heart surgeon Sukumaran Nair, who later told a colleague he "could have done some more dry-run training," Newcastle Civic Centre heard.
Expert assistants in the use of the sophisticated robot, known as proctors, were present for only some of the procedure.
Paul Renforth, a co-ordinator in the use of robotics at the Freeman, told coroner Karen Dilks the proctors left part-way through without any staff being aware they were going.
'Organs shut down'
Mr Renforth, who was in and out of theatre, said the atmosphere in the room was tense.
He received a phone call from Mr Nair after Mr Pettitt's death, who told him "the procedure had not gone as planned", the inquest heard.
The operation was planned to repair a mitral valve, but damage was caused to another part of Mr Pettitt's heart and it had to be changed to open heart surgery.
Pathologist Nigel Cooper said: "By the end of the surgery the heart was functioning very poorly."
Efforts to help Mr Pettitt, from Whitley Bay, failed and his organs began to shut down.
Simon Haynes, clinical director of cardiothoracic services at Newcastle Hospitals NHS Foundation Trust, said Mr Nair had approached him the month before to get permission to carry out the operation.
Dr Haynes said he agreed "slightly hesitantly", but with the knowledge that proctors would be present.
The inquest continues.