Hostility between surgeons said to have contributed to an increased death rate forced a hospital to seek mediation.
Inspectors have ordered immediate action to improve the cardiac surgery unit at London’s St George’s University Hospitals NHS Foundation Trust.
Complex heart operations have been moved out of the unit since September to allow “improvements to be made”.
St George’s said its “cardiac surgery service is safe, but further improvements are needed”.
The hospital carries out about 1,000 cardiac operations every