Robotics: Emerging technology will help bring cardiac surgery up to speed
Robotics: Emerging technology will help bring cardiac surgery up to speed
Totally remote, endoscopic CABGs should be possible in a few years
One day soon you may peer into the OR only to find an isolated patient undergoing a cardiac procedure while his or her surgery team sits several feet away staring into a computer monitor and manipulating what appear to be joysticks. A closer look at the patient would reveal robotic arms that reach within his thoracic cavity and "see" where to go next while manipulating, cutting, and sewing.
In Europe this scenario is a reality today, and within a few years, say experts, totally endoscopic, robotic, and remote coronary artery bypass grafts (CABG) will be a possibility in this country. Two robotic systems are positioning themselves to reach that Food and Drug Administration (FDA)-approved goal, and Cost Management in Cardiac Care spoke with surgeons who have experience with each.
Zeus (Computer Motion, Santa Barbara, CA) was recently approved by the FDA for feasibility studies at Penn State Geisinger Health System’s Milton S. Hershey (PA) Medical Center — a big step in moving the robot toward the market. (See photos, pp. 88-89.) The other major player, DaVinci (Intuitive Surgical, Mountain View, CA), was projected to be installed at Ohio State University Medical Center in Columbus in July.
Randall Wolf, MD, director of the minimally invasive cardiac surgery and robotics program and associate professor of surgery at Ohio State University, is the only American cardiac surgeon who has done clinical coronary bypasses using the DaVinci system. He has performed the totally endoscopic procedures in Leipzig, Dresden, and Frankfort, Germany.
Wolf says that both the Zeus and DaVinci systems offer the possibility of a total endoscopic coronary bypass operation. Both robotic systems enable surgeons to do through ports the same operation they now do through open incisions. In his words, "It’s no longer necessary to have the hand inside the body cavity in order to suture coronary arteries."
Both these technologies will change the way we do heart surgery, says Wolf. "Visualization systems get better each year, and some now allow the surgeon to see more clearly than he sees with his own eyes."
For the patient, he says, the technologies promise less pain and a quicker recovery. Going through the breastbone is equivalent to breaking the femur, he says, and a broken leg takes six weeks to heal. "This bone trauma is eliminated with an endoscopic CABG approach."
"When I do a minimally invasive bypass," says Wolf, "I mobilize the mammary artery endoscopically through a port, then I make a small incision for the anastomosis. There’s no breaking or removal of ribs generally, and the procedure is done on a beating heart. This allows a single arterial bypass to the front of the heart."
The one part of a bypass that surgeons have been unable to do endoscopically is to sew an anastomosis. "Even though I do a totally endoscopic mammary mobilization," says Wolf, "I still have to make an incision to suture. The robotic systems offer an alternative to that last part of the procedure. It allows a surgeon to do a completely endoscopic anastomosis."
Taking down the mammary artery
The DaVinci system allows a surgeon to sit down and do the whole procedure — including mammary artery mobilization, preparation, and the anastomosis — robotically. "That is the main difference between the two systems — the Zeus system cannot at this point take down the mammary artery," says Wolf.
The DaVinci system allows for all the necessary wrist angles inside the chest 6 mm from the target. The robotic arms have tiny wrists that swivel and rotate like a real hand. An advantage to the OR team is that everyone sees the same thing the surgeon sees and from the same angle. Everyone is involved in the procedure.
"With the DaVinci system," says Wolf, "the whole procedure can be done endoscopically and remotely by the surgeon sitting at a console. Nothing is for free, though; right now, the procedure is done on a still heart, so some sort of coronary-pulmonary bypass machine has to be used while the anastomosis is being performed."
The advantage of MIDCAB (minimally invasive direct coronary artery bypass) is that generally surgeons don’t have to stop the heart. "I anticipate that we will be able to do a totally endoscopic bypass on a beating heart in the future," says Wolf. "When we reach that goal, it will be a viable alternative for the patient with limited coronary disease. This is a truly minimally invasive procedure."
The initial investment cost is higher for the DaVinci system than for the Zeus system because DaVinci includes a 3-D camera and display; whereas the Zeus system is an open platform and is compatible with a hospital’s existing visualization equipment, including the 3-D Vista Series 8000. Zeus costs $750,000 installed; that includes the surgeon’s workstation or console, chair, and the three robotic arms that are attached to the table. It accepts other companies’ instruments, and system purchasers are not required to buy specific instruments from Computer Motion as part of the installation.
"The initial installation cost for DaVinci is $850,000," says Albert Starr, MD, head of the Heart Institute at St. Vincent Hospital in Portland, OR. "The cost per case for disposables is no greater than other cardiac surgeries." He points out that the cost of the complete system is about the same as for one intensive care bed. "A cardiac cath lab costs about $1.5 million," he says, "so, for a cardiac program to spend $850,000 is not out of line with the cost of other capital equipment."
Personnel costs anticipated to be lower
It hasn’t been proven, he says, but personnel costs may be less using robotic systems, because fewer people are involved in the surgery than are needed with surgery by hand. In Wolf’s experience, the nursing staff for DaVinci can be limited to one scrub nurse and one circulating nurse. "There would certainly not be any increased personnel cost," he says.
Wolf says he doesn’t know how this is going to sort out regarding cost. Any new technology is more costly at the beginning, and the only way to get meaningful numbers is to follow some cases. "Costs are in the initial purchase and, of course, for the disposables and draping system," he says. "Some of the system’s instruments have a limited lifetime."
Robots don’t face one problem every surgeon knows — hand tremors and fatigue. The surgeon sits at a computer terminal yards from the operating table. Using the Zeus system, three arms are positioned inside the patient’s chest through pencil-sized holes. One of the arms is a voice-activated camera, the AESOP 3000, that beams close-up pictures of the patient’s heart to the computer screen and allows computer-enhanced positioning. If the surgeon orders, "AESOP up," the camera inches up to show a better view. By moving the joysticks, the surgeon directs Zeus’ two pincer-style arms in stitching.
During currently available minimally invasive heart surgery, doctors operate through three- or four-inch incisions instead of sawing open the breastbone. The alternative to open-heart procedures is popular with patients because it promises less pain and faster healing. But some experts say it is difficult to operate in that confined area with long-handled instruments, and others say the surgery is risky compared with standard open-heart procedures. The precision offered by Zeus and DaVinci enables safe heart surgery through tinier incisions — the robots place stitches within 1/10 mm to 1/20 mm accuracy.
No incision using a robot
How does an endoscopic CABG on a beating heart differ from a MIDCAB procedure? Robert Emery, MD, director of the heart transplant program at Abbott Northwestern Hospital in Minneapolis, is quick to stress that the procedure using the robotic arms is quite different from the MIDCAB procedure — there is no incision using the robot. "There are just quarter-inch punctures to accommodate the ports for the robot arms and the camera," he says.
Where the MIDCAB uses a small incision to sew the LIMA (left internal mammary artery) to the LAD (left anterior descending coronary artery), the robotic procedure uses port access. This is video-directed surgery, and as such there is no direct visualization. "We won’t be using the heart-lung machine; we’ll be operating on the beating heart, as in the MIDCAB procedure," he says. (See box, p. 86, for more information about MIDCAB.)
"MIDCAB involves a minithoracotomy, an incision between the ribs," explains Michael Connor, RN, the director of the center for advanced surgery at Sarasota (FL) Memorial Hospital, "and can involve two to four bypasses on the front of the heart. The procedure for which we’re interested in using robotics is a closed-chest procedure involving about five 5 mm to 10 mm punctures in the thoracic cavity." Trocars holding an endoscope and multiple instruments are placed in the openings.
Wolf explains that MIDCAB, three to four years old now, is a minimally invasive technique that allows a bypass without a sternotomy, the heart-lung machine, and manipulating the aorta. "The mammary artery is typically mobilized under direct vision," he says.
A tireless assistant’
Emery says his staff is not using Zeus for cardiac surgery yet because the FDA has not allowed anyone outside of the Penn State program to operate on patients with it. But it is in use in Europe, specifically in Munich, Germany, and Paris. This past February, the world’s first clinical multivessel CABG was performed using the Zeus system; and last November, the world’s first clinical beating heart CABG was accomplished, both in Munich.
"We are in training," says Emery. "We do use the robotic arm — the FDA-cleared AESOP — to hold the camera, but not the one that does the suturing." The AESOP is, in Emery’s words, "a tireless assistant that moves with you." Voice- controlled, it moves in 16 directions — up, down, in, out, left, right — when it is told to. "It’s steady as a rock and follows you along as you operate," he adds. He is soon going to "Robot Camp" where he and others will be trained to use the Zeus robotic system in human cadavers to harvest the LIMA for use as a bypass graft.
Emery says that a totally endoscopic CABG will alleviate much of the post-op pain that patients get from having the chest wall split and held up on retractors. "The technique eliminates having to hold the chest up; instead, you put puncture holes in the left side of the chest and take the artery down. You don’t take a chance of dislocating cartilage by using the retractors."
Surgeons, Emery says, are aiming for a total robotic bypass for selected patients — those with only one or two bypasses — that will in essence be same-day heart surgery. Patients will be admitted in the morning and go home the next day. He sees that goal coming to pass over the next 10 years.
Ralph J. Damiano Jr., MD, chief of cardiothoracic surgery at Hershey, is the only one who has used the Zeus robotic suturing device in this country as part of approved cardiac feasibility studies. Last December, Damiano performed the first robotically assisted bypass — an open-chest procedure — as part of an FDA Investigational Device Exemption Phase I study. "In the near future," Damiano stated in a news release, "we expect to take the next step and perform completely closed-chest heart surgery." The endoscopic, but open-chest, procedure involves sewing the LIMA to the LAD — "one of the most effective grafts in bypass surgery," says Emery. "They have done 10 human cases so far at Hershey. Because the FDA protocol states that we can do only that one LIMA to LAD graft, and because it’s a feasibility study, the other grafts have to be done by hand, not by the Zeus arms."
Connor says Sarasota has used approved components of the Zeus system since 1996. "We’re waiting for the FDA go-ahead to begin a multicenter clinical trial," he says.
"We’re in the infancy stages right now and nowhere near the ultimate goal, which is to do a fully endoscopic coronary artery bypass on a beating heart," says Jeff Reinbolt, clinical development specialist for Computer Motion. "Once that’s accomplished, potentially the procedure could mean a one- to two-day stay maximum."
Not quite ready for prime time
The endoscopic procedure on a beating heart is currently not possible. "It will take a few years to develop all the techniques necessary for that goal to be a reality," Connor says. The two main barriers are:
(1) "We have to develop a technique to stabilize the area of the graft on the beating heart. A stabilizing device exists now for the open-heart procedure, but nothing similar has been developed for the endoscopic, closed-chest technique.
(2) "Also, nothing has been developed to anastomize the proximal graft — the graft that goes into the aorta — especially in a multiple bypass case. In cases of one or two bypasses, you can use the internal mammary artery as your conduit. But if there are several arteries to be bypassed, you have to take either a radial artery or the saphenous vein as your graft material, and hook them up to a blood supply."
Reinbolt elaborates: "The robotics are already there for suturing, but those other obstacles have to be overcome before this becomes a reality."
"Research goes much slower than you think it will," says Connor. "A ballpark guess on how long this will take is between two and five years."
"Younger physicians just coming out of school who have laparoscopic experience [may] pick up the robotic techniques quickly; but if a surgeon has been doing traditional cardiac surgery for 30 years and has never picked up an endoscopic instrument, it takes a bit longer — "on average about 40 hours of use," says Connor. "We’ve just completed the first stage of our cardiovascular nursing staff education on the robotic instruments."
The center for advanced surgery at Sarasota does about 1,600 heart procedures a year. "Our team is very interested in using this new technology," says Connor. "We had six two-hour training sessions to bring them up to speed on the instruments. Then we took the equipment into an OR and did dry runs to answer questions such as, Where do you put this? Where do you put that? How do you drape? At what point do you hook things up? How is the patient positioned? How perfused?’ Our next step will be to do one or two more sessions prior to our first procedure on a human here. The staff is very excited about it."
But how authentic is testing the devices on bloodless cadavers? Would the robot’s pincers slip on a living patient’s blood? Computer Motion is currently training surgeons on cadavers for the anatomy and live animals for the realistic blood flow so they will be able to control the robot properly.
"The training is on dead human tissue first, then on live animals so that bleeding can be dealt with," Reinbolt says. "Working with a fresh-frozen cadaver is more realistic than working with an animal except for the bleeding factor — there is bleeding, but no arterial spurting. And most surgeons are not familiar with thoracic endoscopy, so they are not familiar with that anatomy from that point of view."
Like lap chols: It’s just a matter of time
Why are these facilities and surgeons interested in the robotic systems? Connor says that Sarasota has always been interested in doing clinical research. At any time, the facility is doing 15 to 25 projects under FDA auspices and has a large, progressive cardiac program.
"Why would cardiac surgery not follow the trend of other subspecialties toward minimally invasive procedures?" he asks. He was involved in the early days of laparoscopic gall bladder surgery around 1984, when those procedures took several hours: "Colleagues asked us why we spent four to six hours doing the procedures laparoscopically when it took them only 45 minutes in the traditional, open-abdomen way. It was a struggle. Now, lap chols [laparoscopic cholecystectomies] are the gold standard, and they take half an hour. Because of that experience, I believe it’s just a matter of time to develop the technology and skill levels of the surgeons to the point that this cardiac procedure can also be done endoscopically."
Starr has used the DaVinci system, including the suturing component, but only on animal models. "You use the same motions as though you were holding the instruments in your own hands," he explains. "It’s a very good mimicker of motions. Whatever you do with your fingers and wrist and elbow is completely imitated by the robotic arm. You use the same actions as you would intuitively if you were holding the instruments yourself."
He says that the system’s usefulness will increase as it becomes more sophisticated. "The current system is good for certain types of thoroscopic surgery through a small incision. You can do a microvalve repair and other straightforward intracardiac defects like atrial-septal defects."
But coronary artery surgery is its best application. "It’s been demonstrated clearly that you can take down the internal mammary artery and use it as a graft," Starr says. "You can do straightforward coronary anastomoses with the system."
Clearly beneficial to the patient
Starr says that benefits for the patient are clearly those of minimally invasive surgery in general — rapid recovery, less assault on the individual, and more comfort. "The new technology will enable a kind of cardiac surgery which is already being done in other specialties. Minimally invasive surgery is common for gall bladders and joints. This device will make endoscopy more applicable to cardiac problems."
Now DaVinci has just two robotic arms, but Starr says, "we expect it to continue to develop; and, as it does, there will probably also be an additional console for a surgical assistant." The system has just been approved by Germany’s equivalent of the FDA and is being used in Dresden and Leipzig on a daily basis. "Over the next six months, we anticipate that there will be tremendous growth of this methodology," says Starr.
At the June meeting of the International Society of Minimally Invasive Surgery in Paris, papers were presented dealing with the learning curves and mistake frequency using computer-assisted instruments with either a full range of motion (seven degrees of motion), or with more limited range (four degrees). It was found that surgery is done more safely and rapidly with seven degrees of motion. "The Zeus system does not have the seven degrees, as does DaVinci," says Starr. "They may very well develop that in the future."
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