University Hospital of Wales 'addressing' danger claims
26 July 2013 Last updated at 19:33 BST
Some departments at Wales' biggest hospital are dangerous with patients dying while waiting for heart operations, according to its own surgeons.
They also claim that patients, including children, have suffered, because scheduled operations have been postponed at the University Hospital of Wales, Cardiff.
Adam Cairns, chief executive of Cardiff and Vale University Health Board, told Wales Today's Jamie Owen the NHS organisation was addressing the problems.
He told the programme that 12 patients had "very sadly" died over a 15 month period while on the cardiac waiting list.
He said they could not be certain whether any one of those deaths was avoidable but shortening the times people waiting reduced the risk.
Mr Cairns said the pressures over the last winter were unprecedented in his 30 years experience.