A surgeon assisting a pioneering robot heart operation on a man who died "lost sense of time", an inquest has heard.
Stephen Pettitt, 69, died after an operation to repair a mitral valve in his heart in March 2015 at Newcastle's Freeman Hospital.
Assistant surgeon Thasee Pillay told Mr Pettitt's inquest he "wasn't aware of time" during the procedure.
But he said he did tell the surgeon in charge "we have a problem" when sutures in the heart became "criss-crossed"
The robotic surgery wasn't abandoned until after Mr Pettitt developed a bleed in his heart which blinded the robotic camera.
Open heart surgery was then carried out on the patient but he died later in hospital.
Mr Pillay told the inquest at Newcastle Civic Centre: "During new procedures sometimes you get caught up in the fact, 'let's get it done'."
Mr Pillay, who had been involved with other robotic controlled operations but none involving the specific type of heart surgery Mr Petitt was having, said robotic operations carried out by less experienced surgeons are likely to be slow.
He said surgeons need to carry out 40 robotic operations "to overcome the learning curve".
The inquest also heard expert doctors called proctors had been brought in to attend Mr Pettitt's operation, which was the first of its kind at the Freeman Hospital and one of the first in the UK.
But Mr Pillay said the two proctors left during the operation.
"I assumed they'd just taken a coffee break," he said, adding: "I've never had experienced proctors not stay throughout surgery."
The inquest continues.