National Geographic : 2019 May
valve filled with water and grass seeds, allowing him to conceptualize patterns of blood flow and how the valves open and close, details of which were finally confirmed in the 1960s. More than anything, Leonardo’s sketches opened Wells’s eyes to the exquisite logic of the heart’s structure and mechanics—not just what the organ looks like but also why it evolved the way it has. One autumn morning Wells stands over a patient’s open chest in his Papworth operating theater and motions me closer. “See it? It’s astonishing,” he says, pointing to the mitral valve. “ Think of the complexity that the body has to go through to make this valve.” Wells’s surgical approach is guided by the maxim he learned from Leonardo: Each part of the valve’s complex makeup—its leaflets, cords, and papillary mus- cles—is meant to be there, designed to sustain the forces thrust upon it. This has fundamentally shaped the way Wells fixes ailing valves. “ You see that little thing in my forceps? That’s the ruptured cord,” he says. “That’s the source of the problem.” Wells could opt to remove the entire valve and replace it with an artificial model, an approach favored by many surgeons. Instead I watch as he painstakingly replaces every cord with Gore-Tex sutures, preserving as much of the original structure as he can. Leonardo could not predict a surgical approach, but he taught Wells to look carefully, to stop and think, and to fully embrace the valve’s inherent and master- ful ability to do its job, a capability Wells seeks to retain in every cardiac operation he performs. “That was the paradigm shift,” says Wells, who collected his insights in a 256-page book, The Heart of Leonardo. A continent away, Leonardo’s Codex on the Flight of Birds has perme- ated the Stanford University Bio-Inspired Research and Design (BIRD) lab of David Lentink, a biologist and mechanical engineer. When I visit, Lentink hands me a piece of paper with queries explored by Leonardo that he and his 10 graduate students are still trying to answer: How does wing motion in air result in thrust? How do birds’ muscles control the THE CARTOGRAPHER TODAY The Virginiabased National Geospatial Intelligence Agency uses sophisticated technology to collect data about physical features. NGA maps provide critical infor mation during disas ters. Here, screens show highresolution images of Antarctica.