I took this picture during my first visit to the operating room to photograph cardiac surgery. I have photographed many surgeries since, from Seattle to Boston to Brazil, but this photo is one of the most powerful images I have made to date. There's an ominous, dark power in it.

The photo was made during a minimally invasive procedure in which the surgeon does the entire quadruple bypass through a small hole in the patient's chest instead of sawing through the breastbone (a procedure called a sternotomy) and prying the chest open with retractors.

In this photo you can see the surgeon's gloved hand probing through the small hole that gives him access to the heart. Though he first had to saw through three ribs and remove them to reach the heart, each one was numbered with a Sharpie pen to assure that they would be re-inserted in the correct order after the surgery was finished.