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To gain additional perspective on cardiac surgery, Riviere became a frequent visitor to Zenati's operating room. Observing procedures there sparked in him a research analogy. Rather than a robotic arm or hand-held device trying to impose its will on the beating heart, why not inconspicuously land a robot directly on the heart's surface just like a lunar module landing on the unpredictable surface of the moon? Hence, HeartLander.

His initial HeartLander concept was a two-piece robot linked by a spring. Using suction-cup feet, the robot could, in theory, be instructed by a surgeon to crawl inchworm-style to any point on the epicardium—the heart's surface. (Riviere's daughters dubbed it "Heart Slinky" because of its resemblance to Slinky Dog from the movie Toy Story.) HeartLander would adhere to the epicardium and be stationary, relative to the heart's movement, allowing it to perform precise surgical procedures while riding the heartbeats. And because no part of the heart would be immobilized, the tiny robot wouldn't disrupt the organ's rhythm.

Zenati understood the value and potential of robotic assistance in the OR. The most up-to-date technology for performing cardiac surgery is the Intuitive da Vinci Surgical System, a multi-armed robot controlled by the surgeon using an interface module about the size of an ATM. Zenati had performed his groundbreaking beating-heart procedure using the Computer Motion Zeus system, da Vinci's precursor. Da Vinci allows a surgeon to operate with great precision, but necessitates the use of endoscopic tools, which incurs all of the related undesirables: multiple entry ports, difficulty accessing all areas of the heart, deflation of the left lung. Zenati believed HeartLander would be a dramatic improvement: "We needed a new paradigm: single port procedures."

To allow HeartLander entry into the chest cavity, he developed a single-entry incision approach just below the sternum. Through this technique, HeartLander avoids the lungs. With an additional incision in the pericardium—the membrane that envelops the heart—the surgeon can place HeartLander, by hand, on the heart's apex.

Once Zenati's operative approach and Riviere's HeartLander concept were in place, Riviere and Zenati, in 2002, joined Patronik with bringing HeartLander to life. Starting with his observations of a pig's defiantly beating heart, Patronik spent the next six years working on a mechanical design small enough to fit beneath the pericardium, yet tough enough to not be ripped apart by the heartbeat.

Patronik began by concentrating on HeartLander's inchworm locomotion, in early tests creeping the robot over the surface of a heart substitute—a balloon filled with gel. Lacking motors small or reliable enough to power HeartLander's deliberate movements on the epicardium, he developed a design in which the robot is tethered to its mothership by a supple tail. Running through the tail are the robot's lifelines. Air tubes create the suction for HeartLander's feet. An injection tube supplies an on-board needle for surgical treatments. And drive wires, powered by motors on the mothership, create the robot's steps by extending and contracting the distance between HeartLander's front and rear bodies while the feet adhere and release unbeknownst to the heart. The surgeon can manipulate the drive wires to turn the robot, moving it across the heart in a sidewinding motion.

Patronik produced multiple versions of HeartLander, each one progressively smaller as tests continually resulted in the robot getting stuck between the heart and its protective pericardium, which fits the heart like a latex glove. Finally, Patronik was able to miniaturize HeartLander to around the size of a battery, close to half the size of the first prototype. Guided by the mothership, this miniaturized version nosed its way between the surface of the heart and the pericardium with ease.

After six years of robotics innovation, with funding from the Pittsburgh Foundation and the National Institute of Health, HeartLander is ready for a journey to the dark side of the heart. Patronik wheels the mothership into the OR at UPMC Presby. Takeyoshi Ota, cardiothoracic surgery research associate at the University of Pittsburgh and the fourth member of the HeartLander team, preps the porcine patient.

Patronik wants to provide validation of HeartLander's mastery of the heart. The back side of the heart has always been a difficult region for surgeons to access. HeartLander is already the first robot to successfully navigate the surface of the heart, but if it can successfully perform a test procedure on the heart's posterior, it could be a particularly impressive feat in the eyes of the surgical community. For HeartLander, this task requires it to crawl upside down, the weight of the heart pressing the robot against the spine.

Ota establishes an itinerary, and Patronik programs the robot to move independently to a series of predetermined points on the epicardium, all while the pair tracks its progress on a magnetically generated 3D map of the pig's heart. As planned, HeartLander rounds the backside of the pig's heart, accomplishes its task, and returns without difficulty.

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