Digital Surgery
Computer-assisted techniques promise to extend the cardiac surgeon's reach—even beyond the O.R.
Ralph J. Damiano, Jr. MD
IN A RESEARCH LABORATORY at the School of Medicine, Ralph J. Damiano Jr., MD, professor of cardiac surgery, is in the midst of a dramatic surgical simulation-- but the scene in no way resembles traditional heart surgery. Damiano is not wearing the special glasses that magnify his patient's coronary vessels or the headlight that illuminates his surgical field. He is not holding any of the tiny scalpels, scissors or clamps that make microsurgery possible. Most strangely, he is not even standing at the operating table.
Six feet away, Damiano is seated at a computer console, staring at a monitor that displays the vessels within an animal heart, at 10 to 15 times their normal size. He is wearing a headset fitted with a microphone; his hands grasp joysticks with handles that mimic surgical tools. And looming over the nearby operating table is a space-age instrument: a robotic device with three giant arms. One holds an endoscope--a camera and light that illuminates the heart's interior; the other two hold minute instruments for stitching, grasping and cutting the coronary vessels.
"AESOP," calls Damiano, and the computer answers with an affirmative tinkle. "Move in. Stop. Back. Right. Left. Stop," Damiano commands, as the endoscopic arm of the robot responds obediently to every new order. "Save position one," he adds, and the computer commits a position to memory, ready to return to it later. "Position one saved," replies a robotic voice.
While Damiano's voice directs the endoscope, his hands deftly work the controls for the other two robotic arms. In real procedures--any one of the 20 coronary bypass procedures he did in 1998Ð1999 as part of a groundbreaking clinical trial, while he was on the faculty at Penn State University--he has used these arms to perform the surgical work, while studying the monitor carefully to gauge his progress.
"Robotically assisted surgery" is what most people call this remarkable new technology but Damiano-- concerned that people will picture autonomous, 'Star Wars'-style robots--prefers the term computer-assisted surgery. Either way, he says, this technology effectively takes a surgical instrument and splits it in half. Between the handle (which he holds) and the instrument tip (inside the patient) is a computer using sophisticated software to digitize the surgeon's maneuvers and relay them in real time to the robot arms. By digitizing the movement, the computer can be used to perfect each surgical maneuver.
This new form of surgery, Damiano says, represents nothing less than a surgical earthquake that will send shock waves throughout the entire field over the coming decade. As robots improve and become less expensive, more disciplines will adopt these computer-assisted techniques and find exciting new ways to use them--transforming current procedures and developing new ones, even on a cellular level.
The School of Medicine will be at the forefront of this revolution, with a research program in computer-assisted surgery that will become one of the most active in the United States. Damiano has just received Food and Drug Administration and when he receives institutional approval, probably by early November, he will begin a new round of clinical trials on coronary bypass patients using robotically assisted techniques. In November, he will teach them to other surgeons in his first course at the new Washington University Institute of Minimally Invasive Surgery which opened in late October.
"This is surgery meeting the information age," says Damiano, chief of cardiac surgery within the division of cardiothoracic surgery at the School of Medicine and Barnes-Jewish Hospital. "For the first time, we are integrating computers into the operating room. While the information technology revolution has totally changed American business, it has not had a dramatic impact on the technical performance of surgery--until now. What we're seeing is the early days of a revolution that may transform the way surgery is done."
Bypassing conventional surgery
Conventional coronary bypass surgery has several limitations. To reach the heart, surgeons must make an 18-inch incision or "median sternotomy," dividing the patient's breastbone; to avoid the problems of operating on a beating heart, they place the patient on cardiopulmonary bypass, using the heart-lung machine. These procedures mean some pain during recovery, a risk of surgical morbidity--and a month or two of recuperation. To move toward more minimally invasive surgery, cardiac surgeons have recently tried two strategies: decreasing the size of the incision and operating "off-pump," on the beating heart. But a large scar--and the attendant recovery problems--still remain. So nearly four years ago, Damiano and several colleagues around the world began looking at ways to perform bypass surgery endoscopically, though a series of small "ports" in the chest, none wider than the diameter of a pencil.
To do that, they would need long instruments, some 12 to 18 inches in length--a far cry from the usual 4- to 5-inch instruments, so easily cradled in the hand. These long instruments, they found, augment even the faintest tremor. Since coronary arteries are the size of strands of spaghetti, eliminating any extra motion is extraordinarily important.
"Heart surgeons all have steady hands, but it's impossible to hold these long instruments steady when you are working on really small vessels," says Damiano. "To date, performing endoscopic coronary artery surgery by hand has been totally impossible--beyond the limits of dexterity of any heart surgeon in the world."
But a robotic arm, assisted by computer technology, does not face these same limitations. In fact, a computer can filter out high-frequency motion from the electronic signal, thus removing all traces of tremor--and increasing the surgeon's dexterity. At the same time, it also can scale the surgeon's motions, so that Damiano and others can perform microscopic motions at high magnification--but still perceive them as gross, easy-to-perform movements.
"While surgical loupes typically give us from 2.5x to 3x magnification, this robotic endoscope/camera gives us 10x to 20x magnification, which enhances our visualization of anatomical detail. We also can get that visualization right down into the surgical field," says Damiano. "And the camera is being held by a robotic arm that never gets tired and is under direct voice control."
The robotic system that Damiano has been helping to test and develop is the ZEUS Robotic Surgical System, made by Computer Motion, Inc., of Santa Barbara CA. Another model is the Da Vinci telemanipulation system, made by Intuitive Surgical, Mountain View CA, and now in use at several European centers.
Damiano and his colleagues at Penn State were among the first in the world to begin actively working with this technology. For two years, they honed their techniques on inanimate objects, then moved to cadaver models and animal studies. Finally, they received FDA approval for a trial on 10 patients, the first in North America to undergo endoscopic bypass grafting. The results were so successful that they received approval to perform 10 more; this time, two other centers joined them, with an additional 13 patients.
"In our series, we had no complications related to using the robotic system. Also, postoperative angiograms showed that all the grafts were open at two months without any significant stenosis, so we were very happy with the results," says Damiano.
Surgical hyper-evolution
Still, FDA restrictions in those trials prevented Damiano from using fully endoscopic procedures with any of his patients. He could use computer-assisted technology to do bypass surgery on a single vessel, the left anterior descending coronary artery (LAD). But most needed bypass grafts on other arteries as well, so Damiano had to operate on them using standard open-heart techniques, including a median sternotomy and cardiopulmonary bypass.
During this next clinical trial at the School of Medicine and Barnes-Jewish Hospital, which will also include eight to 10 other major U.S. centers, Damiano expects that the FDA will still impose strict guidelines. But as each trial offers new evidence of the technology's safety and efficacy, he says, the patient base will broaden. In Canada and Europe, where regulations are less strict, medical centers have already begun doing bypass on more than one coronary vessel with excellent results.
Damiano is enthusiastic about the future prospects for this technology. For patients, it may mean a faster recovery, less pain--and three small scabs on the chest rather than a long incision. For surgeons, sitting at a console means less physical exhaustion, while eliminating high-frequency motion may mean a longer active surgical career. And a surgical expert in a different medical center --even another country-- could easily assist in a procedure through satellite or fiberoptic links. The School of Medicine plans to become a major player in this kind of "tele-mentoring," Damiano says.
Right now, computer-assisted technology is still evolving, as companies work to incorporate three- dimensional visualization and even the sense of touch, so important to many surgeons. Doctors must learn to access vessels other than the LAD and even explore applications in heart valve surgery. The price of this equipment must also come down to make this technology affordable and cost-effective.
But endoscopic procedures still have the potential to transform cardiac surgery, just as they have already revolutionized gallbladder removal, some urological procedures and many orthopaedic excisions, through arthroscopic techniques. According to "Moore's Law," says Damiano, "computer processing power doubles every 18 months." If a computer is interposed between a patient and surgeon, he adds, the surgeon's technical ability also may increase exponentially as well.
"I call this a 'surgical hyper-evolution,'" he says. "We'll do an operation, then suddenly our technical ability will dramatically improve and that operation will become obsolete as we discover better, less invasive ways to do the same procedure. As a surgeon, I find that tremendously exciting because we will no longer be shackled by our physical limitations. Soon our surgical horizons may only be limited by our imaginations."
