Given the high stakes, it’s hardly a coincidence that Beth Israel’s and New York University’s medical centers are among the facilities most aggressively pursuing the technology in cardiac surgery. “New York is one of the most competitive markets for heart care in the hospital business,” says Richard Gemming, executive director of the Heart Institute for Continuum Health Partners Inc., which runs Beth Israel and a half-dozen other formerly independent hospitals in the vicinity. Due to consolidation and a New York State medical regulatory system that limits the number of cardiac centers, a few operating rooms must vie for the area’s large and sophisticated patient population; if a healthcare facility falls below a mandated number of operations necessary to maintain surgical expertise, the hospital can lose its cardiac approval.
In this atmosphere of intense competition, it’s also not surprising that Beth Israel and NYU are adopting rival equipment-da Vinci and ZEUS systems. In principle, the hardware is similar, consisting of a computer-mediated surgical workstation with a high-quality video display and hand-input devices, a wired network to communicate surgeons’ gestures, and a cart bearing the system’s robotic arms. In practice, however, da Vinci and ZEUS differ in crucial ways.
By design, da Vinci’s console is meant to be immersive: The surgeon looks down at a three-dimensional view of the patient’s innards, as picked up by a two-chip charge-coupled device (the same type of chip used in digital cameras) video element in the scope at the end of one of the stainless-steel rods. To assure a top-notch, stereoscopic, nonfatiguing view, mirrors reflect images from two full-sized monitors, hidden within the bulky console, into the left and right eyepieces of the visor port.
By contrast, the ZEUS console is more like a computer workstation: The surgeon sits opposite a vertical screen-available with 3-D stereo imaging using lightweight polarizing glasses. An in-depth display, it turns out, may not be as crucial as the subtle color cues available from monocular high-definition video, especially at 10 times magnification, which is beyond the augmentation afforded by simple optics worn by a nonrobotically assisted surgeon.
For the heart surgeons, both types of high-quality displays make it possible to see anatomical features in precise detail. “You can see anatomical structures you’ve never seen before,” says NYU’s Eugene Grossi; as director of the hospital’s cardiovascular research laboratory he was responsible for adding a Sony high-definition TV system to the ZEUS equipment. Says Beth Israel’s Shennib of his da Vinci console: “It’s the best medical visualization I’ve ever seen.”
Beyond the displays, other key differences can be found in the systems’ hand controllers and coupled robotic arms and instruments. ZEUS replicates the endoscopic instrumentation used in conventional minimally invasive surgery. (An endoscope is a slender optical tube passed into the body to allow the surgeon to view an operation.) The surgeon activates the long-stemmed chopstick-like instruments by compressing V-shaped handles. This control device, though perhaps not as intuitive as other types, involves a set of manipulations to which practitioners of minimally invasive surgery are already accustomed.
The da Vinci system adds another wristlike articulation to the instrument tips and an extra degree of freedom to its hand controllers. “It provides better dexterity. The motion is close to having your hand inside the patient,” says Shennib. But not exactly. The da Vinci’s force feedback, a computer-synthesized tactile resistance felt by the surgeon when making an incision or sewing a suture, provides a cue to instruments’ actions but doesn’t accurately replicate what is sensed in hands-on work. According to Shennib, “You feel resistance from the [robotic] arms when you’re pushing on the controls, but not the delicate feedback of pulling or pushing on tissue.”