Ana Maria has never been to Machu Picchu. The 61-year-old always wanted to visit the mountain ruins but she suffers from hypertension, and doctors warned that the extreme altitude could cause her blood pressure to rise dangerously high. Today, dressed in a white gown and hairnet, she will explore its ancient walls and pyramids for the first time.She's in a private medical clinic in Mexico City, and laughs nervously as she's wheeled into a windowless operating room. The surgeon takes a Sharpie and draws a large circle on her left thigh, paints on several layers of iodine, then injects a local anesthetic into the skin. Inside the circle is a fatty lump, a lipoma around six centimeters across, which he is about to remove.Ana will be awake for the operation, and she's feeling scared. As the surgeon readies his scalpel, her blood pressure is 183/93, even higher than usual. Patients undergoing procedures like this often have to be sedated to cope with the pain and anxiety of being under the knife, but not today. Instead, José Luis Mosso Vazquez, who is supervising the operation, fits a sleek, black headset over Anna's eyes and adjusts the Velcro straps.The surgeon makes his first cut and the blood spills in a crimson stream down Ana's leg. She's surrounded by medical equipment--stools, trolleys, swabs, syringes, with super bright surgical lamps suspended above the bed and her vital signs displayed on monitors just behind. But Ana is oblivious. She's immersed in a three-dimensional re-creation of Machu Picchu. She begins her journey with a breathtaking aerial view of the ancient city clinging to the mountainside, before swooping down to explore the details of stepped terraces, moss-covered walls and tiny stone huts.Mosso watches her carefully. A 54-year-old surgeon at Panamerican University in Mexico City, he's on a mission to bring virtual reality into the operating room, using the high-tech distraction technique to carry out surgeries that would normally require powerful painkillers and sedatives, with nothing more than local anesthetic. He's trying to prove that reducing drug doses in this way not only slashes costs for Mexico's cash-strapped hospitals, but cuts complications and recovery times for patients, too.But today, he's not sure if his headset is going to be enough. He hopes the virtual reality will help Ana to avoid unnecessary medication, but if she becomes anxious during the surgery, her already-high vital signs might spike. He has prepared an intravenous line, ready to administer emergency medication if required.The surgeon pulls a large, pearly glob of tissue from Ana's thigh, his fingers easing under her skin as he carefully snips it free. Then he mops the blood and stitches the wound. The procedure has taken just 20 minutes, and there are smiles all round as Ana thanks the team. Because of the virtual reality, she says, she barely noticed the scalpel slicing her flesh: "I was transported. Normally I'm very stressed, but now I feel so, so relaxed."The monitors back up her story. Throughout the surgery, her blood pressure actually fell.