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Dive into the research topics where Dennis Yang is active.

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Featured researches published by Dennis Yang.


Endoscopy International Open | 2015

Evaluation of anesthesia management, feasibility and efficacy of peroral endoscopic myotomy (POEM) for achalasia performed in the endoscopy unit

Dennis Yang; Davinderbir Pannu; Qing-qing Zhang; Jeffrey D. White; Peter V. Draganov

Introduction: Data on anesthesia management and outcomes associated with peroral endoscopic myotomy (POEM) performed exclusively in the endoscopy unit are limited. In this prospective study, we evaluated the safety of anesthesia management, and the feasibility and efficacy of POEM performed exclusively in the endoscopy unit. Methods: A single-center prospective study of consecutive patients with achalasia treated with POEM in an endoscopy unit was performed. Safety of anesthesia management and POEM were determined by procedure-related adverse events. Feasibility was assessed by completion rate. Short-term efficacy was established by clinical success (Eckardt score ≤ 3) and by comparing Eckardt and dysphagia scores before and after POEM. Results: Patients (n = 52) underwent POEM under general anesthesia with endotracheal intubation and positive pressure ventilation. Aspiration was prevented by keeping patients on a clear liquid diet before the procedure without requiring a prior esophagogastroduodenoscopy for esophageal content clearance. POEM completion rate was 96 % (50/52 patients). There was no post-POEM bleeding. Postprocedure leak was observed in one patient (3 %). Four patients (7.7 %) experienced mucosal injury, three of them were treated uneventfully endoscopically and one required laparoscopic repair. Clinical success was achieved in 88 % of patients. There was a significant decrease in the mean Eckardt score (8.1 to 1.4) and dysphagia score (2.4 to 0.4) (P < 0.0001) at the one month follow up after POEM. Conclusion: Anesthesia management of POEM is safe in the endoscopy unit and aspiration can be prevented without requiring prior esophagogastroduodenoscopy for esophageal content clearance. Overall, POEM performed by a gastroenterologist in the endoscopy unit was feasible and effective for the treatment of achalasia.


Clinical Gastroenterology and Hepatology | 2017

Efficacy and Safety of Peroral Endoscopic Myotomy for Treatment of Achalasia After Failed Heller Myotomy

Saowanee Ngamruengphong; Haruhiro Inoue; Michael B. Ujiki; Lava Y. Patel; Amol Bapaye; Pankaj N. Desai; Shivangi Dorwat; Jun Nakamura; Yoshitaka Hata; Valerio Balassone; Manabu Onimaru; Thierry Ponchon; Mathieu Pioche; Sabine Roman; Jérôme Rivory; François Mion; Aurélien Garros; Peter V. Draganov; Yaseen B. Perbtani; Ali Abbas; Davinderbir Pannu; Dennis Yang; Silvana Perretta; John Romanelli; David J. Desilets; Bu Hayee; Amyn Haji; Gulara Hajiyeva; Amr Ismail; Yen I. Chen

BACKGROUND & AIMS: In patients with persistent symptoms after Heller myotomy (HM), treatment options include repeat HM, pneumatic dilation, or peroral endoscopic myotomy (POEM). We evaluated the efficacy and safety of POEM in patients with achalasia with prior HM vs without prior HM. METHODS: We conducted a retrospective cohort study of 180 patients with achalasia who underwent POEM at 13 tertiary centers worldwide, from December 2009 through September 2015. Patients were divided into 2 groups: those with prior HM (HM group, exposure; n = 90) and those without prior HM (non‐HM group; n = 90). Clinical response was defined by a decrease in Eckardt scores to 3 or less. Adverse events were graded according to criteria set by the American Society for Gastrointestinal Endoscopy. Technical success, clinical success, and rates of adverse events were compared between groups. Patients were followed up for a median of 8.5 months. RESULTS: POEM was technically successful in 98% of patients in the HM group and in 100% of patients in the non‐HM group (P = .49). A significantly lower proportion of patients in the HM group had a clinical response to POEM (81%) than in the non‐HM group (94%; P = .01). There were no significant differences in rates of adverse events between the groups (8% in the HM group vs 13% in the non‐HM group; P = .23). Symptomatic reflux and reflux esophagitis after POEM were comparable between groups. CONCLUSIONS: POEM is safe and effective for patients with achalasia who were not treated successfully by prior HM. Although the rate of clinical success in patients with prior HM is lower than in those without prior HM, the safety profile of POEM is comparable between groups.


The American Journal of Gastroenterology | 2017

Comprehensive Analysis of Adverse Events Associated with per Oral Endoscopic Myotomy in 1826 Patients: An International Multicenter Study

Yamile Haito-Chavez; Haruhiro Inoue; Kristin W. Beard; Peter V. Draganov; Michael B. Ujiki; Burkhard H.A. Rahden; Pankaj N. Desai; Mathieu Pioche; Bu Hayee; Amyn Haji; Payal Saxena; Kevin M. Reavis; Manabu Onimaru; Valerio Balassone; Jun Nakamura; Yoshitaka Hata; Dennis Yang; Davinderbir Pannu; Ali Abbas; Yaseen B. Perbtani; Lava Y. Patel; J. Filser; Sabine Roman; Jérôme Rivory; François Mion; Thierry Ponchon; Silvana Perretta; Vivien W. Wong; Roberta Maselli; Saowanee Ngamruengphong

Objectives:The safety of peroral endoscopic myotomy (POEM) is still debated since comprehensive analysis of adverse events (AEs) associated with the procedure in large multicenter cohort studies has not been performed. To study (1) the prevalence of AEs and (2) factors associated with occurrence of AEs in patients undergoing POEM.Methods:Patients who underwent POEM at 12 tertiary-care centers between 2009 and 2015 were included in this case–control study. Cases were defined by the occurrence of any AE related to the POEM procedure. Control patients were selected for each AE case by matching for age, gender, and disease classification (achalasia type I and II vs. type III/spastic esophageal disorders).Results:A total of 1,826 patients underwent POEM. Overall, 156 AEs occurred in 137 patients (7.5%). A total of 51 (2.8%) inadvertent mucosotomies occurred. Mild, moderate, and severe AEs had a frequency of 116 (6.4%), 31 (1.7%), and 9 (0.5%), respectively. Multivariate analysis demonstrated that sigmoid-type esophagus (odds ratio (OR) 2.28, P=0.05), endoscopist experience <20 cases (OR 1.98, P=0.04), use of a triangular tip knife (OR 3.22, P=0.05), and use of an electrosurgical current different than spray coagulation (OR 3.09, P=0.02) were significantly associated with the occurrence of AEs.Conclusions:This large study comprehensively assessed the safety of POEM and highly suggests POEM as a relatively safe procedure when performed by experts at tertiary centers with an overall 7.5% prevalence of AEs. Severe AEs are rare. Sigmoid-type esophagus, endoscopist experience, type of knife, and current used can be considered as predictive factors of AE occurrence.


Diagnostic and Therapeutic Endoscopy | 2013

Peroral Endoscopic Myotomy for the Treatment of Achalasia: An Analysis

Dennis Yang; Mihir S. Wagh

Achalasia is a motility disorder of the esophagus, characterized by aperistalsis of the esophageal body and incomplete relaxation of the lower esophageal sphincter (LES). Treatment of achalasia is currently aimed at decreasing the resting pressure in the LES. Peroral endoscopic myotomy (POEM) is an emerging novel endoscopic procedure for the treatment of achalasia with initial data suggesting an acceptable safety profile, excellent short-term symptom resolution, low incidence of postprocedural gastroesophageal reflux (GER), and improvement in manometric outcomes. Further prospective randomized trials are required to evaluate the long-term effectiveness of this promising technique compared to other treatment modalities for achalasia. In this review we outline the technical aspects of POEM, summarize the available data on safety and outcomes, and suggest future directions for further advancement of this minimally invasive approach for the treatment of achalasia.


Surgery Research and Practice | 2016

Through Thick and Thin: Identifying Barriers to Bariatric Surgery, Weight Loss Maintenance, and Tailoring Obesity Treatment for the Future

Donevan Westerveld; Dennis Yang

More than one-third of the adults in the United States are obese. This complex metabolic disorder is associated with multiple comorbidities and increased all-cause mortality. Bariatric surgery has been shown to be more effective than medical therapy and has been associated with weight loss maintenance and decreased mortality. In spite of these well-established benefits, less than 1% of candidates undergo surgery due to multiple factors, such as patient and physician perceptions and attitudes, patient-physician interaction, lack of resources, and cost burden. Furthermore, even in patients who do undergo bariatric surgery and/or alternate weight loss interventions, long-term weight control is associated with high-risk failure and weight regain. In this review, we highlight some of the current barriers to bariatric surgery and long-term weight loss maintenance and underscore the importance of an individualized multidisciplinary longitudinal strategy for the treatment of obesity.


Pancreas | 2014

Predictors of malignancy in patients with suspicious or indeterminate cytology on pancreatic endoscopic ultrasound-guided fine-needle aspiration: a multivariate model.

Dennis Yang; Koorosh Moezardalan; Dennis Collins; Shailendra S. Chauhan; Peter V. Draganov; Chris E. Forsmark; Mihir S. Wagh

Objective The aim of this study was to evaluate predictors of malignancy in pancreatic lesions with suspicious or indeterminate endoscopic ultrasound fine-needle aspiration (EUS-FNA) cytology. Methods Suspicious/indeterminate EUS-FNA cytology was identified from our database. Stable imaging, benign pathology, or survival for 12 months after EUS-FNA was considered benign. Diagnosis of malignancy was based on positive pathology, local invasion/metastasis on imaging, or death within 12 months from cancer-associated causes. Univariate analysis was performed to compare variables between benign and malignant lesions. Multivariate analysis (covariates: age [<70 or ≥70], appearance [solid/cystic], size [<20 or ≥20 mm], and serum CA19-9 [<40 or ≥40]) was performed using binary logistic regression. Results There were 81 patients with suspicious or indeterminate cytology. Final diagnosis was cancer in 55 (67.9%) of 81 (adenocarcinoma in 40/81 [49.4%], “other neoplasms” in 15/81 [18.5%]) and benign in 26 (32.1%) of 81. Univariate analysis revealed a difference in age, lesion size, solid/cystic characteristics, and serum CA 19-9 between benign and malignant lesions. Only elevated serum CA 19-9 was independently associated with a diagnosis of malignancy on multivariate analysis. Conclusions Age, lesion size, and solid/cystic characteristics on EUS were not independently associated with cancer. Pancreatic lesions with suspicious/indeterminate cytology and elevated serum CA 19-9 should be considered as concerning for a malignant diagnosis.


Endoscopy | 2017

Lumen-apposing covered self-expandable metal stents for short benign gastrointestinal strictures: a multicenter study

Dennis Yang; Jose Nieto; Ali Siddiqui; Brian P. Riff; Christopher J. DiMaio; Satish Nagula; Amr Ismail; Saowanee Ngamreungphong; Mouen A. Khashab; Mihir S. Wagh; Demetrios Tzimas; Jonathan M. Buscaglia; Daniel S. Strand; Andrew Y. Wang; Shailendra S. Chauhan; Chris E. Forsmark; Peter V. Draganov

Background and study aim Use of the fully covered self-expandable metal stent (SEMS) for benign luminal gastrointestinal (GI) stricture (BLGS) has been limited by the migration rate. The role of the lumen-apposing metal stent (LAMS) for BLGS is not well defined. We assessed the safety, feasibility, and efficacy of LAMS for the treatment of BLGS. Patients and methods This was an observational, open-label, retrospective, single-arm, multicenter consecutive case series of patients undergoing LAMS placement for BLGS. Technical success was defined as successful placement of the LAMS. Short- and long-term clinical success rates were defined as symptom improvement/resolution with indwelling stent and after stent removal, respectively. All adverse events and additional interventions were recorded. Results A total of 30 patients (mean age 51.6 years; 63.3 % women) underwent LAMS placement for GI strictures (83.9 % anastomotic). Median stricture diameter and length were 4.5 mm (range 2 - 10 mm) and 8 mm (range 5 - 10 mm), respectively. Technical success was achieved in 29 patients (96.7 %), with an adverse event rate of 13.3 %. The stent migration rate was 8.0 % (2/25) on follow-up endoscopy. Short-term clinical success was achieved in 90.0 % (27/30) at a median of 60 days (interquartile range [IQR] 40 - 90 days). Most patients (19/23; 82.6 %) experienced sustained symptom improvement/resolution without the need for additional interventions at a median follow-up of 100 days (IQR 60 - 139 days) after LAMS removal. Conclusion This multicenter study demonstrated that LAMS placement represents a safe, feasible, and effective therapeutic option for patients with BLGS and is associated with a low stent migration rate. Our initial findings suggest that future prospective comparative studies are needed on the use of LAMS, endoscopic dilation, and conventional SEMS. .


Gastrointestinal Endoscopy | 2016

EUS-guided, through-the-needle forceps: clenching down the diagnosis

Roxana M. Coman; Alexander Schlachterman; Ashwini K. Esnakula; Peter V. Draganov; Dennis Yang

A 68-year-old man was referred for recurrent episodes of acute pancreatitis over the course of 1 year. CT of the abdomen and pelvis revealed a 22 19–mm cyst in the body of the pancreas communicating with a nondilated main pancreatic duct (Fig. 1A). On EUS, the cyst was multilobulated and characterized by thick septae. EUSguided FNA was initially attempted, but no fluid could be aspirated for analysis. With the 19-gauge needle (EchoTip Ultra; Cook Medical, Bloomington, Ind) still within the cyst, a toothed microforceps (Moray microforceps; U.S. Endoscopy, Mentor, Ohio) was inserted through the needle for further tissue procurement. Under EUS guidance, targeted biopsies were performed from the cyst wall (Video 1, available online at www.giejournal.org), (Fig. 1B). Cytology revealed groups of mucinous epithelial cells with pleomorphism and architectural overlapping consistent with a mucinous cystic neoplasm (Fig. 1C). The patient underwent distal pancreatectomy. A surgical specimen revealed a mixed-type intraductal papillary mucinous neoplasm with carcinoma in situ. In summary, EUS guided, through-the-needle microforceps can be considered for tissue procurement in select cases


Gastrointestinal Endoscopy | 2016

Prospective evaluation of CT esophagram findings after peroral endoscopic myotomy

Davinderbir Pannu; Dennis Yang; Patricia L. Abbitt; Peter V. Draganov

BACKGROUND AND AIMS Peroral endoscopic myotomy (POEM) is a procedure with potential for serious adverse events. Postprocedure imaging is routinely done, yet there is no consensus on the optimal imaging protocol. We describe a novel and simple CT esophagram protocol for evaluation after POEM and for reporting the full spectrum of radiographic findings and subsequent interventions. METHODS This was a single-center prospective study of consecutive patients treated with POEM evaluated with CT esophagram. RESULTS Eighty-four consecutive patients who had POEM performed underwent CT esophagrams. The most common findings were pneumomediastinum (85.7%), pneumoperitoneum (66.7%), subcutaneous emphysema (52.4%), and pleural effusion (46.4%). Other findings included retroperitoneal air (38.1%), pneumothorax (19%), atelectasis (14.3%), intramural air in the esophagus and/or stomach (13.1%), pericardial effusion (2.4%), and pneumopericardium (2.4%). Five patients required intervention based on CT findings. In 1 patient, a leak was detected on CT esophagram before any clinical manifestation, facilitating prompt intervention and avoiding potential serious outcomes. Four patients were diagnosed with pneumonia and were treated with antibiotics. There was frequent postprocedural atelectasis, which prompted the introduction of routine incentive spirometry in all postoperative POEM cases. CONCLUSIONS CT esophagram is a simple and accessible imaging test for routine postoperative POEM evaluation. Numerous and dramatic postprocedure radiographic findings may be expected and demonstrated with this imaging modality. Although most of these findings may not require intervention, some are of potential significance, and early identification may help modify postprocedure management. ( CLINICAL TRIAL REGISTRATION NUMBER NCT01832779.).


Gastrointestinal Endoscopy | 2014

Per-oral endoscopic tunneling for restoration of the esophagus (POETRE)

Mihir S. Wagh; Dennis Yang; Disaya Chavalitdhamrong; Peter V. Draganov

Per-oral endoscopic myotomy (POEM) has recently gained popularity for the endoscopic treatment of achalasia. We extend the application of this technique by demonstrating a novel dual-endoscope approach for therapy of complete esophageal obstruction: per-oral endoscopic tunneling for restoration of the esophagus (POETRE). Dual-endoscope simultaneous endoscopy (1 endoscope via the mouth and another simultaneously inserted retrograde through the G-tube tract) was performed for the treatment of peptic/radiation esophageal stricture with complete obstruction. A 5-cm complete esophageal obstruction was seen (distance between antegrade and retrograde endoscopes on fluoroscopy). Per-oral endoscopic submucosal tunneling was performed (Video, available online at www.giejournal.org) via the antegrade endoscope and was extended caudally

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Patrick Yachimski

Vanderbilt University Medical Center

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