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Biomedical subjects

Per-Ola Park

Publications and source records attributed to Per-Ola Park.

8 recordsLinked to original sources

Transgastric anastomosis by using flexible endoscopy in a porcine model (with video).

BACKGROUND: Transgastric flexible endoscopic anastomosis might offer advantages over open and laparoscopic surgery, especially for bariatrics or patients with obstructive malignancy. OBJECTIVE: To develop methods for performing transgastric anastomosis. DESIGN/RESULTS: Twelve gastrojejunal anastomoses were formed in pigs weighing 27 kg to 38 kg (6 each in survival and nonsurvival groups) by using a per-oral double-channel gastroscope. The stomach was penetrated with a needle-knife guidewire combination and bow-sphincterotome incision. The small intestine (SI) was grasped with a snare-over-forceps method and pulled into the stomach for suturing. Sutures were placed in pairs through the deep muscle of the stomach and small intestine to join the tissues securely. The SI was incised with a needle-knife to open the anastomosis. Anastomoses were placed close to the cardioesophageal junction for bariatric purposes or in the antrum for pancreatic bypass. Survival studies in 6 pigs showed anastomosis patency at 7 to 10 days. CONCLUSION: Gastrojejunal anastomosis was accomplished via the transgastric route by using a new double-channel endoscopic method.

Animals↗

Development of a new access device for transgastric surgery.

Flexible endoscope-based endoluminal and transgastric surgery for cholecystectomy, appendectomy, bariatric, and antireflux procedures show promise as a less invasive form of surgery. Current endoscopes and instruments are inadequate to perform such complex surgeries for a variety of reasons: they are too flexible and are insufficient to provide robust grasping and anatomic retraction. The lack of support for a retroflexed endoscope in the peritoneal cavity makes it hard to reach remote structures and makes vigorous retraction of tissues and organs difficult. There is also a need for multiple channels in scopes to allow use of several instruments and to provide traction/countertraction. Finally, secure means of tissue approximation are critical. The aim was to develop and test a new articulating flexible endoscopic system for endoluminal and transgastric endosurgery. A multidisciplinary group of gastrointestinal physicians and surgeons worked with medical device engineers to develop new devices and instruments. Needs assessments and design parameters were developed by consensus. Prototype devices were tested using inanimate models until usable devices were arrived at. The devices were tested in nonsurvival pigs and dogs. The devices were accessed through an incision in the wall of the stomach and manipulated in the peritoneal cavity to accomplish four different tasks: right upper quadrant wedge liver biopsy, right lower quadrant cecal retraction, left lower quadrant running small bowel, and left lower quadrant exposure of esophageal hiatus. In another three pigs, transgastric cholecystectomy was attempted. The positions of the device, camera, and endosurgical instruments, with and without ShapeLock technology, were recorded using laparoscopy and endoscopy and procedure times and success rates were measured. Instrument design parameters and their engineering solutions are described. Flexible multilumen guides which could be locked in position, including a prototype which allowed triangulation, were constructed. Features of the 18-mm devices include multidirectional mid body and/or tip angulation, two 5.5-mm accessory channels allowing the use of large (5-mm) flexible endosurgical instruments, as well as a 4-mm channel for an ultraslim prototype video endoscope (Pentax 4 mm). Using the resulting devices, the four designated transgastric procedures were performed in anesthetized animals. One hundred percent of the transgastric endosurgical procedures were accomplished with the exception of a 50% success for hiatal exposure, a 90% success rate for wedge liver biopsy, and a 33.3% success rate for cholecystectomy. A new endosurgical multilumen device and advanced instrumentation allowed effective transgastric exploration and procedures in the abdominal cavity including retraction of the liver and stomach to allow exposure of the gallbladder, retraction of the cecum, manipulation of the small bowel, and exposure of the esophageal hiatus. This technology may serve as the needed platform for transgastric cholecystectomy, gastric reduction, fundoplication, hiatus hernia repair, or other advanced endosurgical procedures.

Animals↗

Experimental studies of transgastric gallbladder surgery: cholecystectomy and cholecystogastric anastomosis (videos).

BACKGROUND: Transgastric flexible endoscopic surgery might offer advantages over open and laparoscopic surgery. The aim of this study was to develop methods for performing transgastric biliary endosurgery. METHODS: Cholecystectomies and biliary anastomoses were performed in 8 anesthetized pigs (27-30 kg) in nonsurvival studies. Two endoscopes passed perorally were inserted through the stomach wall after needle-knife incision. Endoscope-induced pneumoperitoneum allowed viewing and manipulation of the gallbladder with both endoscopes independently. The cystic duct was dissected, clipped, and transected. Cholecystectomy was performed with one of two methods: either by using two endoscopes, or a single endoscope and a 5-mm-diameter grasping instrument inserted transabdominally. Clips and sutures were used to attach the gallbladder to the stomach wall, and an incision was made to form a cholecystogastrostomy. In survival experiments in 8 pigs, transgastric incisions were closed with endoscopic sutures. RESULTS: The gallbladder was successfully removed in 8 pigs (nonsurvival experiments). The time for the procedure ranged from 2.5 hours to 40 minutes and decreased with experience. At postmortem examination, clips placed on the cystic duct and the artery were secure. An anastomosis was successfully formed between gallbladder and stomach in 3 pigs. In 8 pigs, full-thickness incisions in the stomach wall were closed with two to 4 stitches. All 8 pigs survived (median follow-up, 22 days; range 14-28 days). CONCLUSIONS: Transgastric gallbladder surgery, including cholecystectomy and biliary anastomosis, is feasible. Full-thickness gastric incisions were safely closed in survival studies. The efficacy and the safety of transgastric surgery merits further study.

Anastomosis, Surgical↗

Transgastric gastropexy and hiatal hernia repair for GERD under EUS control: a porcine model.

BACKGROUND: Endoluminal operations for gastroesophageal reflux currently are limited by the inability to visualize and manipulate structures outside the wall of the gut. This may be possible by using EUS. The aims of this study were the following: to define the EUS anatomy of structures outside the gut that influence reflux, to place stitches in the median arcuate ligament, to perform posterior gastropexy, and to test the feasibility of crural repair under EUS control in pigs. METHODS: In survival experiments in 22 pigs, by using a linear-array echoendoscope, the median arcuate ligament and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and thread. These were anchored into the muscle. An endoscopic sewing device was used, allowing stitches to be placed through a 2.8-mm accessory channel to any predetermined depth. New methods allowed knot tying and thread cutting through the 2.8-mm channel of the echoendoscope. RESULTS: Stitches were placed through the gastric wall into the median arcuate ligament, and one stitch was placed just beyond the wall of the lower esophageal sphincter. The stitches were tied together and locked against the gastric wall. Median lower esophageal sphincter pressure, determined manometrically, was 11 mm Hg before surgery and 21 mm Hg after stitch placement (p=0.0002). The length of the lower esophageal sphincter increased from a median of 2.8 cm before the procedure to 3.5 cm after the procedure. At the postmortem, the median force required to pull the tags out of the median arcuate ligament was 2.8 kg. CONCLUSIONS: This study demonstrates that transgastric gastroesophageal reflux surgery, by using stitching under EUS control, can significantly increase lower esophageal sphincter pressure in pigs.

Animals↗

Endoscopic suturing.

We describe the development of endoscopic sewing machines and ancillary equipment for knot tying and thread cutting. We outline the experimental studies in dogs, pigs and baboons prior to the first studies in man. We consider the early results achieved by groups in Europe and the U.S.A., and present the available evidence from peer-reviewed studies and data from numerous abstracts on the use of endoscopic suturing in man for treating gastro-oesophageal reflux. We consider the limitations of the available studies, and outline the requirements for improvements in flexible endoscopic suturing methods.

Animals↗

Transluminal endosurgery: single lumen access anastomotic device for flexible endoscopy.

BACKGROUND: Forming anastomoses between two hollow organs at flexible endoscopy might reduce the need for surgery for obstructing malignancy. Current methods require access to both lumens. The aim of this work was to develop methods of forming an anastomosis at flexible endoscopy, such as a gastrojejunostomy or cholecystoduodenostomy, when access to only one lumen is feasible. METHODS: A modified needle was passed through a large-channel echoendoscope from the accessible lumen into the target hollow organ. An anastomotic device was formed by using two 7F catheter segments, which were pushed over a guidewire into the target, the less accessible lumen. When released, by withdrawing the guidewire, the catheters formed a cross shape and created an anastomosis when compressed against a plate from the accessible side. OBSERVATIONS: These devices were tested in live animal experiments. With an echoendoscope in the stomach, it was repeatedly possible to place needles, threaded tags, and guidewires into the small intestine and gallbladder. In 4 to 7 days, anastomoses were formed in 16 pigs between the small intestine and the stomach, and between the gallbladder and the stomach. The initial diameter of the anastomoses ranged from 3 to 9 mm. No complication occurred. CONCLUSIONS: It is feasible to form anastomoses at flexible endoscopy when access is limited to a single side.

Anastomosis, Surgical↗

Bard EndoCinch: the device, the technique, and pre-clinical studies.

There is, of course, room for improvement. More work is needed to make endoscopic suturing easier, quicker and more reliable. The single most important next goal is to construct a device, which can place multiple stitches without the need to remove the endoscope between each stitch. Devices, which can place two stitches in one go, would be a start. The development of double stitch and multiple stitch devices has been described earlier. The authors are pleased to see two alternative commercial endoscopic sewing devices appear at the last DDW which place two stitches without needing to withdraw the endoscopes--they use a double needle method.

Anastomosis, Surgical↗

A through-the-scope device for suturing and tissue approximation under EUS control.

BACKGROUND: The ability to place sutures under EUS control might allow development of a new type of transluminal endosurgery. The aim of this study was to develop endoscopic methods for suturing to variable predetermined depths in the wall of the GI tract and to allow fixation of adjacent hollow organs under EUS control. METHODS: A suturing device was constructed for suturing under EUS control to any desired depth. Sutures can also be placed into hollow or solid organs within 5 cm of the endoscope tip. The device allows multiple sutures to be placed without withdrawing the endoscope. Stitching, knot-tying, and thread-cutting are achieved through a 2.8-mm accessory channel. RESULTS: Multiple (>100) sutures were placed in predetermined gut wall layers in pigs. Sutures were placed in the gallbladder (n = 7) and small intestine (n = 8) to fix the gallbladder/small intestine to the stomach and allow traction for the insertion of stents and other devices through the 2 lumens. CONCLUSION: A new method for stitching under flexible EUS control is described. This technology was used to place sutures at precise depths in the GI tract. It allowed fixation of other organs to the accessible GI tract for various purposes including delivery of stents and devices for creating anastomoses.

Animals↗