The Operation: Surgery Live

David had a leaky mitral valve in his heart, which was causing him to feel extremely tired and short of breath. A functioning mitral valve only lets blood flow in one direction through the left side of the heart. However, when the valve is damaged, blood can flow the wrong way, resulting in increased pressure on the heart. If David's condition had been left untreated his heart would have eventually failed.

Peter Chaisit-Charles had a suspected tumour in his brain. For the last four years he has suffered from epilepsy, with his lesion causing abnormal electrical activity in the brain. Recently it started to affect his short term memory too. The tumour was growing in the left temporal lobe – the area of the brain that controls our speech and language functions. If the tumour had continued to grow, Peter could have lost part of his ability to talk.

Susan had a hiatus hernia where her stomach protruded through a hole in her diaphragm up into the bottom of her oesophagus. This caused acid reflux, where digestive juices and food from the stomach travel back up the oesophagus. As a result Susan was suffering from chronic heartburn, chest pains and severe discomfort when she ate. She had mild symptoms for 15 years but in the past ten months they had become unbearable. If the condition was left untreated it would have continued to get worse.

Christine had a tumour at the base of her brain in her pituitary gland. This is the body's hormone control centre and the tumour had affected it, causing her body to secrete an excess of growth hormones. Christine's lips had swollen and her shoe size had increased from a size six to a size eight. If the tumour hadn't been removed, the muscles in her heart could have started to grow, restricting blood flow and increasing the risk of a stroke.