Having flown a number of 'Medevac' cases on RPT A330 flights, I can say that there is no problem. IIRC, three x two seats were folded down (rather than removed) and the medical stretcher, which was quite a sturdy piece of kit, was secured, very strongly, in place.
The attending Doctor and Nurse(s) were seated across the aisle in two or three adjacent aisle seats, with additional oxygen bottles and requisite medical supplies secured close by. The medical staff and the cabin crew were briefed to call me in the event of any problems. It never happened; all went very smoothly and the patient was tenderly wheeled to an ambulance, by way of an hydraulic lift, after the other passengers had disembarked.