Christopher C. Thompson

Evaluation of a manually driven, multitasking platform for complex endoluminal and natural orifice transluminal endoscopic surgery applications (with video)

BACKGROUNDnThe Direct Drive Endoscopic System (DDES) is a multitasking platform developed to overcome the limitations of the currently available rigid and flexible endoscopic systems in application to natural orifice transluminal endoscopic surgery (NOTES), single-port laparoscopy, and advanced endoluminal procedures. The system consists of a 3-channel, steerable guide sheath accepting a 6-mm endoscope and two 4-mm articulating instruments. The systems overall design enables the interventionalist to operate instruments bimanually from a stable platform, conveying a laparoscopic paradigm to the functional working space at the distal end of the flexible guide sheath.nnnOBJECTIVEnTo assess the basic functionality of the DDES device in a series of defined exercises by using ex vivo porcine stomachs and 1 in vivo animal model.nnnDESIGNnEx vivo calibration and training exercises, including EMR, full-thickness suturing, and knot tying.nnnSETTINGnAnimal laboratory.nnnINTERVENTIONSnEMR, full-thickness suturing, and knot tying.nnnMAIN OUTCOME MEASUREMENTSnSuccessful completion of specified tasks.nnnRESULTSnIndependent instrument movement with a wide range of motion allowed the interventionalist to perform several complex tasks efficiently. The DDES was able to (1) grasp tissue and hold it under tension, (2) cut through layers of porcine stomach in a controlled fashion, (3) suture, and (4) tie knots.nnnLIMITATIONnEx vivo study.nnnCONCLUSIONSnThis novel multitasking platform demonstrated surgical functionality including triangulation, cutting, grasping, suturing, and knot tying. Preliminary results suggest that the DDES can perform complex endosurgical tasks that have traditionally been challenging or impossible with the standard endoscopic paradigm, and may enable NOTES, single-port laparoscopy, and complex endoluminal procedures.

Transluminal closure for NOTES: an ex vivo study comparing leak pressures of various gastrotomy and colotomy closure modalities.

BACKGROUND AND STUDY AIMSnTransluminal closure is fundamental to the safe introduction of natural orifice transluminal endoscopic surgery (NOTES) into humans. Suture, staples, and clips have been used. We aimed to evaluate the acute strength of various gastrotomy and colotomy closure techniques in an ex vivo porcine model by assessing air leak pressures.nnnPATIENTS AND METHODSnThe following closure modalities were assessed with at least five samples per arm: conventional open/laparoscopic suturing techniques including full-thickness interrupted sutures, double-layer sutures, and purse-string sutures, as well as endoscopic clips and endoscopic staples. Historical values for transgastric closures with hand-sewn interrupted sutures, endoscopic clips, and a prototype endoscopic suture device were used from our laboratorys prior study.nnnRESULTSnUsing Kruskal-Wallis analysis, the overall comparisons were significant ( P = 0.0038 for gastrotomy closure; P = 0.0018 for colotomy closure). Post hoc paired comparisons revealed that the difference between all closure arms versus negative control were significant. Significance could not be established among the various closure arms. However, trends suggested hand-sewn double-layer sutures, endoscopic staples, and both hand-sewn and endoscopically-placed purse-string sutures produced the strongest closures. Furthermore, endoscopic clips appeared sufficient for colotomy closure when ideally placed.nnnCONCLUSIONSnSuture (both hand-sewn and endoscopically deployed) appears to produce the strongest closures in both stomach and colon, with the important caveats that (1) a continuous through-thickness suture track be avoided, such as in the full-thickness closure, or (2) suture holes be buried, such as in the purse-string configuration. When suture tracks are full-thickness, they can serve as leak sites. Staples and clips can produce comparable closures, but only under ideal conditions.

Smart Self-Assembling MagnetS for ENdoscopy (SAMSEN) for transoral endoscopic creation of immediate gastrojejunostomy (with video)

BACKGROUNDnGastrojejunostomy is important for palliation of malignant gastric outlet obstruction and surgical obesity procedures. A less-invasive endoscopic technique for gastrojejunostomy creation is conceptually attractive. Our group has developed a compression anastomosis technology based on endoscopically delivered self-assembling magnets for endoscopy (SAMSEN) to create an instant, large-caliber gastrojejunostomy.nnnOBJECTIVEnTo develop and evaluate an endoscopic means of gastrojejunostomy creation by using SAMSEN.nnnSETTINGnDevelopmental laboratory and animal facility.nnnDESIGNnAnimal study and human cadaveric study.nnnSUBJECTSnYorkshire pigs (7 cadaver, 5 acute); human (1 cadaver).nnnINTERVENTIONSnA transoral procedure for SAMSEN delivery was developed in porcine and human cadaver models. Subsequently, gastrojejunostomy creation by using SAMSEN was performed in 5 acute pigs. The endoscope was advanced into the peritoneal cavity through the gastrotomy, and a segment of the small bowel was grasped and pulled closer to the stomach. An enterotomy was created, and a custom overtube was advanced into the small bowel for deployment of the first magnetic assembly. Next, a reciprocal magnetic assembly was deployed in the stomach. The 2 magnetic systems were mated under fluoroscopic and endoscopic guidance. Contrast studies assessed for gastrojejunostomy leak. Immediate necropsies were performed.nnnMAIN OUTCOME MEASUREMENTSnTechnical feasibility and complications.nnnRESULTSnGastrojejunostomy creation by using SAMSEN was successful in all 5 animals. Deep enteroscopy was performed through the stoma without difficulty. No leaks were identified on contrast evaluation. At necropsy, the magnets were properly deployed and robustly coupled together, resistant to vigorous tissue manipulation.nnnLIMITATIONSnAcute animal study.nnnCONCLUSIONSnEndoscopic creation of immediate gastrojejunostomy by using SAMSEN is technically feasible.

Magnetic retraction in natural-orifice transluminal endoscopic surgery (NOTES): addressing the problem of traction and countertraction

BACKGROUND AND STUDY AIMSnBecause of their reliance on the flexible endoscope, most current procedures in natural-orifice transluminal endoscopic surgery (NOTES) suffer from the inability to vigorously grasp and move tissue or to retract organs. We aimed to assess the use of internal and external magnets that might allow the vigorous multiaxial traction/countertraction required in more complicated NOTES procedures.nnnMETHODSnEx vivo and in vivo porcine model. Study components were: (1) Evaluation of force-distance relationship of this magnetic retraction system using a digital tensiometer. (2) Application of this magnetic retraction system to two procedures in the porcine model: (a) Liver retraction during transcolonic cholecystectomy in five nonsurvival pigs. Procedure time was recorded and compared to historical controls. (b) Mesh positioning for implantation into the anterior abdominal wall for ventral hernia repair in three survival pigs.nnnRESULTSnOver a distance of 5 cm to 0.25 cm, the magnetic force of our system increased from 3 to 90 gramforce (29.42 to 882.60 mN.) In vivo, the magnet system provided robust liver retraction, shortening the procedure time of NOTES cholecystectomy from a historical mean of 68 minutes (range 42 - 90 minutes; n = 5) to 49.6 minutes (range 33 - 61 minutes; n = 3). The magnetic system also greatly enhanced mesh positioning and stability, and these animals survived for 2 weeks without complications.nnnCONCLUSIONSnOur basic system provided critical liver retraction during NOTES cholecystectomy and was also instrumental in moving and stabilizing mesh for implantation during NOTES ventral hernia repair. Magnets can potentially provide the vigorous traction and countertraction required to advance NOTES procedures.

Pancreatic antegrade needle-knife (PANK) for treatment of symptomatic pancreatic duct obstruction in Whipple patients (with video)

BACKGROUNDnEndoscopic decompression of symptomatic main pancreatic duct (MPD) dilation in Whipple patients is often difficult because of stenosis of the pancreaticojejunal (PJ) anastomosis.nnnOBJECTIVEnTo evaluate the feasibility and procedural safety of the pancreatic antegrade needle-knife (PANK) technique, with the goal of restoring antegrade MPD flow, when endoscopic retrograde pancreatography (ERP) and EUS-guided rendezvous fail.nnnSETTINGnTertiary care center.nnnDESIGNnRetrospective series.nnnPATIENTSnThree patients with symptomatic MPD dilation refractory to ERP and EUS-guided rendezvous.nnnINTERVENTIONSnUnder EUS guidance, a 19-gauge echo-needle was used to gain access to the dilated MPD and a Jagwire advanced. After failed attempts at antegrade guidewire passage across the PJ stenosis, deep transgastric MPD access was achieved via a Soehendra stent retriever and balloon dilation. Careful antegrade needle-knife of the stenotic site was performed. A long pancreatic stent spanning the jejunum, MPD, and gastric access site was placed. Four to 8 weeks later, this stent was upsized and converted to a PJ stent, which in turn was removed 4 weeks thereafter.nnnMAIN OUTCOME MEASUREMENTSnTechnical feasibility and complications.nnnRESULTSnAll 3 patients successfully underwent the PANK procedure. Pre- and post-MRCP studies showed the mean MPD diameter decreased 60% from 8.3 mm to 3.6 mm (mean follow-up 8 months). At 24-month follow-up, all 3 patients experienced decreased or resolved pain without further need for MPD intervention.nnnLIMITATIONSnRetrospective study with small numbers.nnnCONCLUSIONSnWhen ERP and EUS rendezvous fail, the PANK procedure using a staged stent strategy seems to be an effective means of MPD decompression.

Three-dimensional intensity distributions in the region of focus of two superposed converging spherical waves

The three-dimensional distribution of intensity in the neighborhood of focus of two converging coaxial spherical waves has been calculated for various focal separations and phase differences between the waves. Lommel functions were used to solve the diffraction integral, and computer techniques were used to generate the complex-field amplitude arrays. Subsequent superposition of the arrays provided contour maps of the intensity distributions.

An Interferometric Approach To Suppression Of Scattered Radiant Energy

The fundamental validity of using an interferometric process to reduce scattered light in optical systems has been examined from a physical optics viewpoint. An elementary scatter nulling interferometer was considered in the context of a simple telescope system as it imaged a distant point source, whose image had been degraded by a single on-axis point scattering source. With the interferometer inserted in the optical train of the telescope, the diffraction image of the point source, and a wavefront model of the scatter source at the focal plane were studied in detail. An expression for gain in signal-to-noise ratio was evaluated for typical cases. An experiment to illustrate the basic concepts of a particular scheme was conducted to demonstrate the viability of the technique.

Management of Post-Bariatric Complications

Abstract Obesity is one of the most significant health problems worldwide, and the prevalence has been increasing over the past decade. Despite improvement in the performance of bariatric surgery, complications are not uncommon. These complications vary according to baseline patient characteristics, the duration of time since the operation, and the type of bariatric surgery performed. Endoscopy is the cornerstone in the diagnosis of postoperative complications after bariatric surgery, and may even be performed in the early postoperative course. With an increasing number of patients being referred for endoscopic evaluation following bariatric surgery, it is essential to develop an understanding of the anatomic changes for optimal assessment and appropriate treatment of these patients. In many cases, endoscopic intervention provides both diagnostic utility and a minimally invasive strategy for management. This chapter will review the major complications, diagnosis, and management of the most commonly performed bariatric surgical procedures including Roux-en-Y gastric bypass, sleeve gastrectomy, laparoscopic adjustable banding, and vertical banded gastroplasty.