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Biomedical subjects

Kazuki Sumiyama

Publications and source records attributed to Kazuki Sumiyama.

12 recordsLinked to original sources
PubMed2007

Endoscopic full-thickness closure of large gastric perforations by use of tissue anchors.

BACKGROUND: A flexible needle-catheter tissue-anchoring device was developed to accomplish full-thickness tissue apposition of the GI wall. The aim of this study was to identify the performance of this device for repair of large iatrogenic gastric perforations in a porcine model. OBJECTIVES: Six pigs. DESIGN: Short-term survival animal study. SETTINGS: Pigs were studied while they were under general anesthesia. Device performance in differing gastric locations and wall thicknesses was assessed by 2 perforations more than 2 cm in size created for each pig along the greater curvature and the anterior wall. INTERVENTIONS: Each perforation was closed by parallel placement of tissue anchor sets sequentially along the length of the perforation. MAIN OUTCOME MEASUREMENTS: One week follow-up endoscopy and necropsy were performed. RESULTS: Twelve perforations were closed with the 48 tissue anchor sets. All animals survived for 1 week without clinical complications. Follow-up endoscopy and necropsy revealed that all tissue anchors remained with firmly held sutures and sealed perforations. CONCLUSIONS: Full-thickness closure with a new tissue-anchoring device simply and successfully repaired large iatrogenic gastric perforations.

Animals↗
PubMed2006

New approach to diagnosing ampullary tumors by magnifying endoscopy combined with a narrow-band imaging system.

BACKGROUND: A newly developed narrow-band imaging (NBI) system, which uses modified optical filters, can yield clear images of microvessels and surface structure in gastric and colonic diseases. In the present study, we investigated the ability of magnifying endoscopy with NBI (MENBI) to diagnose and differentiate between benign and malignant ampullary tumors. METHODS: Fourteen patients, whose ampullas were noted to be significantly enlarged or protruding with conventional endoscopy, were enrolled in the study. Specimens, which were obtained by forceps biopsy, endoscopic papillectomy, and/or surgery, were retrieved for histopathological examination. The correlation between MENBI images and histopathological findings was investigated. MENBI findings were classified as I, oval-shaped villi; II, pinecone/leaf-shaped villi; or III, irregular/nonstructured. In addition, tortuous, dilated, and network-like vessels noted on the ampullary lesions with MENBI were defined as abnormal vessels. RESULTS: In 6 of 14 patients, the ampullary changes were proven to be inflammatory in forceps biopsy specimens, without any evidence of malignancy after more than 1 year of follow-up. In five patients, ampullary lesions were treated by endoscopic papillectomy, and in three, by pancreatoduodenectomy. All adenomas and adenocarcinomas had type II and/or type III surface structures, and patients whose ampulla had a type I surface structure had only inflammatory or hyperplastic changes. In addition, abnormal vessels were seen only in adenocarcinomas and never in adenomas. CONCLUSIONS: MENBI has the ability and potential to predict histological characteristics of ampullary lesions.

Adenocarcinoma↗
PubMed2006

Pilot study of the porcine uterine horn as an in vivo appendicitis model for development of endoscopic transgastric appendectomy.

BACKGROUND: Iatrogenic inflammation of the porcine uterine horn may serve as an in vivo appendicitis model for the development of endoscopic transgastric appendectomy. OBJECTIVE: Five female pigs. STUDY DESIGN: Animal study. SETTINGS: General anesthesia. MAIN OUTCOME MEASUREMENTS: Anatomical appearance and technical feasibility. INTERVENTIONS: Three pigs were used to identify an injectable material that would inflame the uterine horn, and 2 pigs were used for a pilot appendectomy. Three types of materials were individually injected into the bilateral uterine horns, and the ideal material to inflame the uterine horn was injected into the right uterine horn for the last 2 pigs. After 24 hours, the injected uterine horns of the first 3 pigs were assessed and a pilot appendectomy was performed in the last 2 pigs. RESULTS: Ethanolamine oleate (EO) injected uterine horns demonstrated similarities to the inflamed human appendix. Simulations of the appendectomy were successfully performed by using the EO model. LIMITATIONS: Suboptimal existing tools. CONCLUSIONS: This preliminary study demonstrated the technical feasibility to create a model for acute appendicitis by using the porcine uterine horn and transgastric appendectomy.

Animals↗
PubMed2006

New generation argon plasma coagulation in flexible endoscopy: ex vivo study and clinical experience.

BACKGROUND AND AIM: A new argon plasma coagulation (APC) system was developed to improve the conduction characteristics of existing systems and to achieve a true non-contact procedure. We evaluated the new system in an ex vivo experiment and in two different clinical cases. METHODS: Swine gastric walls were cauterized at various current settings and time intervals. The diameter and penetration depth of the cauterized areas were measured. We also describe the use of this method to treat patients with gastric hemorrhagic hereditary telangiectasias and a mucosal gastric cancer. RESULTS: The ex vivo study revealed an improved maintenance of current conduction and greater control of the extent and penetration depth of the cauterization effects on tissue using the new APC system. In the clinical cases, hemorrhagic telangiectasias and an early stage gastric cancer were treated successfully without relapse using the new system. CONCLUSIONS: Improved current conduction and controllability of cauterization corresponding to emission time were demonstrated for the new APC. The new system allows expeditious superficial cauterization of a wide area without any contact with tissue. The therapeutic effect appeared favorable compared with previous APC devices for gastrointestinal applications.

Aged↗
PubMed2005

Prediction of recurrence of esophageal varices-special reference to a role for endoscopic ultrasonography.

The fate of esophageal varices (EV) depends largely on variables of hemodynamics in portal venous system, which has long been studied using various diagnostic modalities. Recent studies have mainly focused on relationship of portal hemodynamics and recurrence of esophageal varices after endoscopic treatment. In particular, there is increasing number of studies using endosonography because it is less invasive and provides high-resolution images of collaterals surrounding the lower esophagus and the upper stomach, which includes left gastric veins and its branches, submucosal vessels in the cardia, paraesophageal collaterals and perforating veins. On basis of those studies, the range of changes to those vessels seems to depend on treatment techniques and the role of each vessel in preventing the elevation of portal pressure following treatment and in recanalization of variceal channels greatly varies. Thus, the underlying pathophysiology of variceal recurrence has been gradually understood. Further studies could enable us to identify the patients, in whom varices would rapidly recur and to choose optimal treatment for each treatment.

Journal Article↗
PubMed2004

Combined use of a magnifying endoscope with a narrow band imaging system and a multibending endoscope for en bloc EMR of early stage gastric cancer.

BACKGROUND: En bloc EMR is performed in Japan as a curative treatment for early stage gastric cancer. However, current methods of EMR are technically difficult and require proficiency in determining the extent of the cancer. This study assessed the feasibility of a new method to obviate these problems and to facilitate en bloc EMR. METHODS: The new method uses two types of endoscopes: a magnifying endoscope with a narrow band imaging system to enhance the definition of mucosal and microcirculatory structure, and an endoscope with multibending tip deflection to maintain orientation during EMR. Forty-two consecutive cases of mucosal gastric cancer treated by EMR were reviewed retrospectively. In 12 of these patients, 12 lesions that fulfilled guideline criteria for EMR were treated by the modified, en bloc EMR method of circumferential incision and snare resection by using the two endoscopes. RESULTS: The rate of complete en bloc resection with the new method of EMR was 91.7%, (11/12). There was no major complication. CONCLUSIONS: The new en bloc resection method for EMR with two endoscopes described here is feasible and may be a safe and a reliable technique for curative treatment of mucosal gastric cancer.

Endoscopes, Gastrointestinal↗
PubMed2003

A linear-array freehand 3-D endoscopic ultrasound.

Recognition of the clinical importance of linear-array endoscopic ultrasound (EUS) has increased. In this study, we developed a linear-array 3-D EUS, a miniature position sensor attached to the tip of the echoendoscope used in freehand scanning. To evaluate the geometrical accuracy of the 3-D reconstruction of the system, the diameter of a sphere-shaped phantom (38 mm) was determined by five examiners and five measurers. Measured size of the sphere was 39.03 +/- 1.29 mm, with variance between examiners and measurers, and interaction of examiners with measurers was not significant. In animal and clinical studies, the system facilitated anatomical interpretation of the EUS images, especially in the pancreatobiliary area and vascular images. We concluded that this system is both accurate and reproducible, and may resolve difficulties in linear-array EUS.

Analysis of Variance↗
PubMed2003

Development of a new three-dimensional endoscopic ultrasound system through endoscope shape monitoring.

We have developed a new three-dimensional (3D) endoscopic ultrasound system (EUS) with convex scanning echoendoscope to diagnose and navigate for endoscopic puncture using the 3D image. To detect the position of the probe and to monitor the shape of the scope inside the body, we use a fiber optic tracking system which is shaped like a ribbon (Shapetape, Measurand Inc.). The fiber optic tracking system could measure bend and twist at each position of the ribbon. The position of the tip of the echoendoscope is allotted to a 2D image, and the system can reconstruct and visualize a 3D image in real-time. We have reported results of our experimental studies and animal studies.

Endosonography↗
PubMed2003

Development of an endoscopic robotic system with two hands for various gastric tube surgeries.

This paper presents the first report on an endoscopic robot with two manipulators which performed surgical work to resect the mucosal layer of the stomach of pigs without penetrating the body surface. We designed and developed an endoscopic surgical robot system which possesses two arm shaped manipulators for various kinds of surgery in the gastric tubes. The distal part of the manipulator functions as forceps and they are able to hold and handle soft tissues through the cooperative efforts of the right and left arms. And it is also able to incise the gastric wall by holding an electronic scalpel (brought in from the instrument channel) with the manipulator on the right side while opening the sectioning plane on the left side which was take out. With this system we succeeded in the mucosal resection of a large portion of the stomach wall of a pig during experimental surgery. It can be said that this is a new approach robotic surgery in the gastric tube with this kind of surgical robot.

Animals↗
PubMed2002

Hemodynamic assessment of the left gastric vein in patients with esophageal varices with color Doppler EUS: factors affecting development of esophageal varices.

BACKGROUND: An understanding of the development of esophageal varices is important in the evaluation of risk of variceal hemorrhage. To clarify factors affecting the development of esophageal varices, the morphology and hemodynamics of the left gastric vein were analyzed with color Doppler EUS. METHODS: Sixty-seven patients with esophageal varices underwent color Doppler EUS. Seventeen had small varices (F1), 32 had medium varices (F2), and 18 had large varices (F3). RESULTS: Hepatofugal blood flow velocity in the left gastric vein trunk increased as the size of the varices increased (p < 0.0001), whereas the diameter did not increase. The left gastric vein bifurcates into anterior and posterior branches. As the size of the varices enlarged, the branch pattern was more likely to be anterior branch dominant (p = 0.041). There was no significant difference between the 3 size groups of esophageal varices with respect to the size of the paraesophageal collaterals. The detection rate and diameter of the perforating vein increased as the size of the varices increased (p = 0.032 and 0.012, respectively). CONCLUSION: Blood flow velocity in the left gastric vein trunk, branches, and perforating veins may regulate blood flow supplying the esophageal varices and contribute to their development. These findings are important to understanding the pathogenesis of esophageal varices.

Adult↗
PubMed2002

A novel 3-dimensional EUS technique for real-time visualization of the volume data reconstruction process.

BACKGROUND: Three-dimensional EUS (3D-EUS) technology has facilitated spatial interpretation of US images. However, acquisition of consecutive US scans is time consuming and difficult. A new 3D-EUS system was developed that negates this problem by allowing rapid image renewal and the efficient production of consecutive US scans. METHODS: Three-dimensional images were reconstructed from a series of 2-dimensional images corresponding to the rotation angle of the echoendoscope as measured with an electromagnetic tracking system. To evaluate the technical feasibility of the system, 3-dimensional images of splenic veins in 2 patients and an esophageal submucosal tumor in a third patient were generated. RESULTS: The 3D-EUS system acquired image data at a rate of 30 frames per second and allowed visualization of these data in real-time. The area of interest was clearly and rapidly portrayed in all 3 patients. CONCLUSION: This study demonstrates the efficiency of the new 3D-EUS system described in this report. Further development of this novel 3D-EUS system may lead to new applications of this technology.

Computer Systems↗