May 22, 2012
Gastrointestinal Surgery Improvements With New Technologies
Studies of technological innovations being presented for the first time at Digestive Disease Week® (DDW) showed increased accuracy coupled with decreased cost, time or invasiveness of gastrointestinal procedures. Use of a new high-definition colonoscope, for example, improved physician confidence in diagnosing small polyps, potentially reducing the amount of polyps sent for pathology analysis and the associated costs. Other studies showed the effectiveness of endoscopic bypass using self-assembling magnets and the potential of a capsule endoscope propelled by a tiny flexible fin and magnet. Finally, the surgical anti-reflux procedure, fundoplication, was found not to improve outcomes in patients treated with radiofrequency ablation to eliminate precancerous esophageal cells.
Three Month Data Following Endoscopic Creation of Durable Gastrointestinal Bypass Using Smart Self-Assembling Magnets: a Rapid, Purely Endoscopic Technique Requiring Only Conscious Sedation (Abstract #1027)
Researchers led by Marvin Ryou, MD, associate physician, Brigham and Women's Hospital and instructor of medicine at Harvard Medical School, endoscopically created a GI bypass by deploying self-assembling magnets for endoscopy (SAMSEN) magnetic devices into the intestines of five pigs. The pigs were scoped every three to six days until creation of an anastomosis, a surgical bypass connecting two parts of the GI tract. The anastomosis was created by magnetic compression, a process that takes advantage of the body's natural healing process to remodel the GI tract.
There are several potential applications for this technology, including weight loss, treatment of type II diabetes and palliation of an obstructing cancer. For a gastrojejunal bypass, the endoscopist would deploy a SAMSEN magnet device in the stomach and its reciprocal magnet device in the small intestine. After initial mating of the magnets, the compressed tissue between the two magnets would die off over several days while tissue remodeling would occur around the points of magnet compression. Eventually, a tunnel would form connecting the stomach and the small intestine. The completely joined magnets would be naturally expelled, leaving behind a clean anastomosis without any foreign material.
Previous studies attempting this kind of procedure used small, solid magnets, which limited the size of the bypass and naturally closed up after a few weeks. Larger magnets could not be delivered endoscopically due to anatomical restrictions. "That is why we came up with the concept of these smart magnets that can self-assemble into larger structures within the GI tract, which in turn, create larger and more durable bypasses," said Dr. Ryou.
Dr. Ryou said the findings are also important because they suggest other potential advantages over surgical bypass. For example, an effective endoscopic method of bypass creation is inherently less invasive because it avoids abdominal incisions of conventional surgery.
Additionally, all of the procedures were performed in under half an hour and the pigs needed only intravenous conscious sedation, meaning they were sedated but without general anesthesia. Avoidance of general anesthesia and its attendant risks could prove beneficial for patients.
Investigators performed necropsies (i.e., autopsies) on all pigs after three months and found that the bypasses remained large and completely open, which had not been previously demonstrated. Weight trends plateaued in the bypass pigs while age-matched, litter-matched controls doubled their weight. Furthermore, no adhesions were found, which represents a significant departure from conventional surgery, and would likely make any subsequent surgical procedures less complicated. Adhesions commonly form post-operatively as a result of inflammation and become potential points of obstruction where intestines can twist, requiring a second surgery. The absence of adhesions could represent a significant step forward for abdominal surgery.
Dr. Ryou cautioned that these results, while promising, are from a small animal study. Furthermore, he does not necessarily advocate a jejuno-colonic bypass for humans, but this type of anastomosis was the most feasible in the animal model. However, he added that while there are additional animal studies to conduct, investigators are very close to commencing human work in this area.
This study was conducted with funding support from the Department of Defense and in collaboration with Beacon Endoscopic.
Dr. Ryou will present these data on Tuesday, May 22 at 10:45 a.m. PT in Room 29a of the San Diego Convention Center, and in the ASGE Video Forum on Tuesday, May 22 at 8:09 a.m. PT in Room 6ab.
Observation of Whole Digestive Tract of a Human by a Single Passage of a Self-Propelling Capsule Endoscope (Abstract #154)
A capsule endoscope called "mini mermaid," which moves forward on the power of a tiny flexible fin and magnet, was safely and painlessly observed throughout the entire human digestive tract in a single examination, Japanese researchers report.
The 12-by-45 millimeter device is propelled by a fluctuating magnetic field, and its position, velocity and direction are controlled by adjusting the waveform of the current in the magnetic coils. It successfully made two runs through the full digestive tract of a 69-year-old male, who easily swallowed the capsule while in a half-sitting position. The stomach and large and small intestines were each viewed in detail.
"Because the mini mermaid allows for simple and easy inspection of the digestive tract, it could be utilized as part of a regular physical checkup and help reduce the risk for cancer, ulcers or bleeding in the digestive tract," said Naotake Ohtsuka, PhD, president of Mu Ltd., which developed the device. Dr. Ohtsuka, an engineer and professor emeritus at Ryukoku University in Seta and chief researcher on the project, was also the volunteer subject in the study's initial trials.
Each examination began with Dr. Ohtsuka drinking 2,000 milliters (ml) of polyethylene glycol to irrigate the digestive tract. After the mini mermaid reached his stomach, he drank 500 ml of water; when it reached the small intestine, he drank an additional 200 ml of water and then 1,000 ml more of polyethylene glycol when it reached the colon. Observation of each gastric organ was optimized by adjusting the device's movement and Dr. Ohtsuka's physical position. He was not sedated for any part of the procedure.
The self-propelled capsule endoscope overcomes the disadvantages of a capsule moved slowly by peristalsis, which limits close inspection to only certain sections of the digestive tract. "This launches the age for safe, painless examination of the total digestive tract," Dr. Ohtsuka said.
Dr. Ohtsuka will present these data on Saturday, May 19, at 11:45 a.m. PT in Room 6f of the San Diego Convention Center.
The VALID Colonoscopy Study Results of a Multicenter Prospective Randomized Controlled Trial on Real Time Colorectal Polyp Diagnosis Using Narrow Band Imaging (NBI) (Abstract #569)
A new high-definition, dual focus colonoscope, which allows close-up detailed examination of the colon, may help doctors more confidently diagnose polyp growth, according to new research jointly conducted by the Veterans Affairs of Kansas City, MO; Palo Alto, CA; and San Francisco, CA. Results of the study on real-time diagnosis and removal has the potential to guide changes in the way colonoscopy is practiced by significantly cutting down on the number of polyps being sent for pathology analysis.
Current technology allows doctors to diagnosis polyp growth during colonoscopy; however, few feel confident enough in their assessment to make a clinical decision. Instead, pathology analysis is ordered to examine polyps and more accurately provide a diagnosis. To try to reduce reliance of pathology analysis, researchers led by Tonya Kaltenbach, MD, Veterans Affairs Palo Alto Care System, conducted a study comparing current colonoscope technology with a new, pre-commercial technology.
Investigators assigned 558 patients to five doctors who randomly used either the old or new colonoscope for endoscopy. More than 1,300 polyps were discovered in 558 patients over a period of 12 months. During real-time polyp examination, doctors were asked to state both a diagnosis and a confidence level for that diagnosis. Polyps were then removed and submitted for final analysis by a pathologist.
Overall, doctors were twice as likely to diagnose small polyps with high confidence using the new colonoscope as compared to the conventional device. Final testing by pathologists confirmed that diagnoses made with the new colonoscope were highly accurate and very similar to pathology results.
"By reducing the number of polyps sent for pathology analysis, we can significantly reduce unnecessary spending," said Dr. Kaltenbach. She added that a majority of doctors were already correct with their initial diagnoses, but that the new colonoscope could give them more confidence to make a clinical decision. "The ability to be confident with the diagnosis during colonoscopy and document our diagnoses with a high-quality polyp image may be all we need to start diagnosing polyps right then and there, making colonoscopy better for our patients."
Dr. Kaltenbach cautioned that real-time endoscopic diagnosis only applies to small polyps and that this strategy should not be used on every polyp found, especially those that are either large or have some sort of irregularities. Polyps with these characteristics should be sent to pathology for further review.
Colonoscopy is the examination of the large bowel using a video camera inserted through the anus. The procedure allows doctors to examine a patient for polyps or "growths" that may develop into colorectal cancer. Nearly all colon and rectal cancers start from polyps, but 90 percent of polyps found during colonoscopy are very small and more than a third actually have no cancerous potential.
The study was partially funded by Olympus America, Inc.
Dr. Kaltenbach will present these data on Sunday, May 20 at 4 p.m. PT in Room 3 of the San Diego Convention Center.
Prior Fundoplication Does Not Improve Subsequent Safety or Efficacy Outcomes of Radiofrequency Ablation (RFA): Results from the U.S. RFA Registry (Abstract #808)
Radiofrequency ablation (RFA), a procedure that uses high-energy waves to eliminate precancerous cells in the esophagus, was shown to be safe and effective in patients who had previously been treated with fundoplication, or surgical anti-reflux procedure, according to new research from a national consortium. However, subjects who had undergone surgery prior to RFA required as many RFA treatments as subjects who did not have surgery, and did not experience better outcomes than subjects without surgery.
U.S. RFA Registry investigators wanted to assess the relationship between prior surgery and the outcome of patients who later underwent RFA. They reviewed 5,539 patients receiving RFA and found that of those, 318 or 6 percent, had a prior surgery. Of these patients, 0.9 percent developed stricture (an abnormal narrowing of the esophagus) after RFA and 1.3 percent were hospitalized. Rates of stricture, bleeding and hospitalization were not statistically different between patients with or without prior surgery.
Patients with Barrett's esophagus, a precancerous condition of the esophagus, are commonly treated either with anti-acid medications or with surgery. Investigators wanted to determine if patients who previously had surgery fared better after the RFA treatment than people who were just taking medicine. "We were surprised that the answer to this question was no," said Nicholas Shaheen, MD, AGAF, professor of medicine and epidemiology and director for the Center for Esophageal Diseases and Swallowing, University of North Carolina, Chapel Hill. "Whether patients were taking medicine or having the wrap, their chances of getting rid of precancerous cells was about the same, and their complication rate from the procedure was about the same."
He added that people might look at these findings and conclude that if they have a reflux problem that is severe enough that it could lead to a precancerous condition, they might try an aggressive approach and have surgery before undergoing other treatments. While the surgery is highly effective in people who need it to control reflux symptoms, he advised against undergoing surgery solely to improve the outcomes of RFA since the study shows that people who have the surgery have about the same outcome from the treatment as the people who have medicine.
Dr. Shaheen said there are a few reasons for this. First, medicines today are generally very effective in cutting the amount of acid that people make, so surgery may not be necessary for good acid control. Additionally, surgery is not always effective. On average, the people who need surgery may have worse reflux than people on medicine. In this situation, even if surgery works better to help patients after RFA, no difference might be noted since the surgery patients were worse off in the first place.
A limitation to the study is that some people who have undergone surgery also take medication, which may influence the results. Dr. Shaheen said that the study is the largest prospective trial on this issue, and that subjects need to be monitored for years to learn about the disease and how it is affected by various treatments. While a registry study such as this does not allow manipulation of patients' treatments by the investigators, the length and size of this study precludes a randomized trial.
Dr. Shaheen said that since these techniques are less than 10 years old, we incompletely understand how well they work in the long term – how durable they are going to be and how much of a decrease in cancer risk we can expect to see from these treatments. This registry will help define these important issues.
This research was funded by GI Solutions, formerly BÃRRX Medical, a subsidiary of Covidien.
Dr. Shaheen will present these data on Monday, May 21 at 2:45 p.m. PT in Room 27b of the San Diego Convention Center.
On the Net: