Doctors at Papworth Hospital in Cambridgeshire have carried out a record number of a highly complex operations that involve draining the body of blood.
Papworth is the only hospital in the UK commissioned to perform Pulmonary Endarterectomy operations, which remove blood clots.
They have completed 850 operations in total - 130 in 2011 alone - and the survival rate is nearly 98%.
The surgery, which involves cooling a patient to 20 degrees and completely emptying the body's circulation of blood, can take up to 10 hours. Its purpose is to remove clots from the pulmonary arteries due to a condition called chronic thromboembolic pulmonary hypertension (CTEPH).