By: Bo Schwerin

It's the violence of it that surprises him, the angry vigor of the beats in contrast to the gentle rhythm in the chest. Nick Patronik stares into the red tunnel the surgeon has opened in the pig's ribs. He has never seen a beating heart before. He turns to a nearby clinician observing the cardiac procedure and says, "It moves a lot more than I thought it would."

The clinician replies, "And you're going to land a lunar module on that thing? Good luck."

Patronik looks back at the heart, wondering if the clinician's skepticism might be warranted. The lunar module is a metaphor, a reference to a project Patronik, a PhD candidate at Carnegie Mellon's Robotics Institute, has undertaken. He's observing this operation to get a sense of the challenge he's in for. His mentor at Carnegie Mellon, Cameron Riviere, has him working on a concept that would stretch the imagination of computer scientists everywhere, ultimately taking the field of surgical robotics to a new frontier: the pulsing surface of the heart itself.

The pig's heart beats defiantly, as if issuing a dare.

Six years later, Patronik wheels a cart through the hallways of Pittsburgh's UPMC Presbyterian Hospital. Bristling with electronics, the cart is the mothership for an explorer that today will attempt a remarkable mission. Resting on top of the cart, shorter than a paperclip and tethered to the mothership by a bundle of flexible wires, is HeartLander.

HeartLander is the brainchild of Riviere, associate research professor at the Robotics Institute, who has long been interested in problems of motion. Namely, differentiating between desired motion and undesired motion—and neutralizing the latter. As a PhD candidate in mechanical engineering, Riviere began developing a filtering system for undesired motion that allows people with movement disorders such as Parkinson's disease to operate computer applications using a joystick. While constructing algorithms that take into account pathological tremor, he became interested in the problem natural, physiological tremor presents for surgeons. Surgeons are known for having steady hands, but they, too, experience small-amplitude shakiness when moving. This isn't problematic when stitching a wound, but for surgeons performing delicate eye surgery, for example, unwanted motion can sabotage a procedure. At Carnegie Mellon, Riviere created Micron, a hand-held, microsurgical tool that constantly adjusts its tip during surgery to negate the surgeon's hand tremor. While testing and improving Micron's design, he began to wonder whether algorithms, similar to Micron's, could help overcome a formidable surgical hurdle when it comes to the heart.

In open-heart surgery, for procedures such as bypass, surgeons cut through the sternum and pull back the ribcage to reach the heart. In some cases, minimally-invasive closed-heart surgery is now an option, in which surgeons operate through small incisions in the chest, all while the heart is still beating. This endoscopic technique eliminates the risk of having to stop the heartbeat and then circulate the patient's blood via a bypass machine, which is what occurs during bypass surgery.

Although the closed-heart approach is an improvement, Riviere knew its constraints. Endoscopic surgical tools, inserted through stiff metal tubes, have only a limited range of access—imagine poking a drinking straw through the side of a Styrofoam cup and moving it around. As a result, multiple entry ports into the chest cavity are often required. Then there's the problem of the left lung: To reach the heart, the lung needs to be deflated. This requires the patient to be attached to an artificial respirator and placed under general anesthesia, which means at least an overnight hospital stay and a greater possibility of dangerous complications.

In the fall of 2001, Riviere, thinking robotics could make heart surgery less traumatic, approached Marco Zenati, professor of surgery at the University of Pittsburgh School of Medicine and adjunct professor at the Robotics Institute. Zenati was well aware of the uses and limitations of surgical robotics: A year before, he performed the first robot-assisted, beating-heart coronary bypass surgery in the United States.

Riviere and Zenati began a series of discussions about developing a robot capable of navigating and working on a beating heart. In approaching the problem of operating on an unstable surface, Riviere studied the existing technique for immobilizing areas of the beating heart. Surgeons would employ small braces that stabilize a portion of the heart. Although the technique was effective, anything that touches the heart, including the braces, causes some disruption to its rhythm.

(Continued …)

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