David Jenkins, a world-leading surgeon at Royal Papworth, performs one of surgery's most technically demanding, and extraordinary, operations. Called a pulmonary endarterectomy (PTE), no other hospital in the UK offers this procedure.

Addenbrooke's and Royal Papworth hospitals in Cambridge are renowned for the expertise of their surgical staff. At both centres, surgeons undertake some of the most complex operations in the world, where technical skill is paramount.

Surgeons Marius Berman and Pedro Catarino take on one of the most difficult transplant procedures at Royal Papworth: the double lung transplant. With donor organs in such short supply, there is even more pressure to execute the operation perfectly.

Surgeons have to balance the considerable risks of a procedure against the risks of not treating their patients' conditions at all. Maureen has an enlarged aorta which could be fatal if it bursts, but the operation to fix it is also very high risk.