To strengthen the valve in your oesophagus, the surgeon usually makes a small cut in your chest in order to reach the oesophagus. Then he/she tightens the valve either by; placing stitches in it and injecting it with a substance that will help it to tighten or by passing an electrical current through it. He/She may also sew the top part of your stomach around the bottom end of your oesophagus in order to strengthen it.
Attribution: BUPA