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Biomedical subjects

Yang K Chen

Publications and source records attributed to Yang K Chen.

15 recordsLinked to original sources
PubMed2006

Safety and efficacy of argon plasma coagulation trimming of malpositioned and migrated biliary metal stents: a controlled study in the porcine model.

BACKGROUND: Argon plasma coagulation (APC) has been used to trim uncovered Elgiloy stents, but the extent of thermal damage and bile duct injury is not known. The goal of this study was to evaluate the safety and efficacy of APC for this application. METHODS: Eight Elgiloy (covered and uncovered) and four nitinol stents were deployed in the bile duct at ERCP in 12 anesthetized pigs. In nine pigs, the excess distal ends were trimmed in vivo using short bursts of APC. Three pigs served as controls. Bile ducts and stent specimens were then harvested for gross and histological examinations by a single-blinded pathologist. RESULTS: APC effectively trimmed all the stents. Seven APC-treated bile ducts and three controls showed epithelial distortion consistent with pressure injury from stent expansion. Two APC-treated bile ducts showed mild thermal injury. The damage was superficial, extending to a maximum depth of 0.1 mm with rare foci involving subepithelial connective tissue. CONCLUSION: APC at indicated settings effectively cuts covered and uncovered Elgiloy as well as nitinol stents, but can cause biliary epithelial injury secondary to conduction of heat and electrical energy. Proper technique and settings should be followed and short bursts of energy judiciously applied in order to minimize this danger.

Animals↗
PubMed2006

A prospective study of complications of endoscopic retrograde cholangiopancreatography and endoscopic ultrasound in an ambulatory endoscopy center.

BACKGROUND AND AIMS: Our aim was to assess the safety of endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound (EUS) in an ambulatory endoscopy center (AEC). METHODS: Complications occurring in consecutive patients undergoing ERCP or EUS from March 2003 to February 2004 at our AEC were recorded prospectively. Comprehensive complications were defined as consensus criteria plus other adverse events: use of reversal agents, unplanned hospital admission, hospitalization beyond planned 23-hour observation, unplanned emergency department or primary care provider visit, and 30-day mortality. RESULTS: A total of 497 patients (median age, 57 y; 82% American Society of Anesthesiologists class II or III) underwent 685 procedures. Monitored or general anesthesia was used in 25% of EUS and 50% of ERCP procedures. ERCP interventions were as follows: biliary or pancreatic stenting (N = 168), stone extraction (N = 70), sphincterotomy (N = 62), sphincter of Oddi manometry (N = 53), other (N = 66). EUS indications were as follows: known or suspected pancreatic mass (N = 103), upper-gastrointestinal mass/submucosal lesion (N = 71), luminal malignancy staging (N = 40), other (N = 96); 52% had EUS fine-needle aspiration. There was follow-up evaluation in 94% of the patients. There were 43 comprehensive ERCP complications (12.9%), 18 (5.4%) of these fit consensus criteria: pancreatitis (N = 14), cholangitis (N = 2), and perforation (N = 2). There were 9 comprehensive EUS complications (2.9%), 2 (.7%) of these fit consensus criteria: pancreatitis (N = 1) and bleeding (N = 1). Other adverse events for ERCP and EUS were as follows: prolongation of 23-hour observation (N = 14), emergency room visits (N = 3), primary care physician visits (N = 6), use of reversal agents (N = 3), unplanned admissions (N = 2), infection (N = 3), and death (N = 1). CONCLUSIONS: ERCP and EUS can be performed in an AEC, provided mechanisms for admission and anesthesia support are in place. The assessment of comprehensive complications is more reflective of adverse events related to ERCP and EUS than consensus criteria alone.

Adolescent↗
PubMed2006

Single-step EUS-guided transmural drainage of simple and complicated pancreatic pseudocysts.

BACKGROUND: Single-step EUS-guided transmural drainage of pseudocysts has been reported, but there are no published prospective studies on clinical outcomes. OBJECTIVE: To assess the safety and the efficacy of single-step EUS-guided placement of large endoprostheses to treat simple and complicated pseudocysts. DESIGN: Prospective cohort study. SETTING: Single tertiary referral center. PATIENTS: Consecutive patients referred for management of symptomatic chronic pancreatic pseudocysts >4 cm in size. INTERVENTIONS: Single-step EUS-guided transmural pseudocyst drainage performed with a linear-array echoendoscope for placement of 10F stents in adults and 7F stents in children. MAIN OUTCOME MEASURES: Complete or partial (>50% reduction) resolution of pseudocyst on follow-up imaging, recurrence, clinical response, and procedure-related complications. Recurrence was defined as the reappearance of a pancreatic pseudocyst in the same location. RESULTS: There were 33 patients, with a mean age of 43 years. Median pseudocyst size was 8.5 cm (range, 4-20 cm). Fourteen patients (42%) had infected pseudocysts, 8 patients (24%) had gastric varices, and 16 patients (48%) had no visible endoscopic bulge. Stent placement was successful in 31 patients (94%). Twenty-seven patients (82%) had complete resolution of a pseudocyst; 4 patients (12%) had partial resolution, with symptom relief. There were 2 major complications and 3 minor complications. Recurrence of a pseudocyst was observed in only 1 patient over a median follow-up of 46 weeks. LIMITATIONS: No randomized treatment arm comparing this technique with conventional endoscopic drainage. CONCLUSIONS: Single-step EUS-guided transmural drainage with large endoprostheses is a safe and effective therapy for patients with simple and complicated pancreatic pseudocysts.

Adolescent↗
PubMed2006

Cholangioscopy and cholangioscopic forceps biopsy in patients with indeterminate pancreaticobiliary pathology.

BACKGROUND & AIMS: We report the usefulness of cholangioscopy in patients with indeterminate pancreaticobiliary pathology. METHODS: A prospective collection of 62 consecutive patients during a period of 2.5 years who were referred to our tertiary referral center for cholangioscopy for indeterminate strictures suspicious for malignancy were included. Tissue sampling followed cholangioscopic visualization. Biopsies were obtained under direct visualization (cholangioscopy-directed) or through the duodenoscope (cholangioscopy-assisted). RESULTS: Sixty-two patients had 72 examinations. Forty patients had nondiagnostic sampling before cholangioscopy. Indications were stricture (n = 67: 16 primary sclerosing cholangitis, 51 non-primary sclerosing cholangitis), ductal dilation, or intraductal mass (n = 5). Biopsies were not performed in 19 because cholangioscopy did not identify suspicious lesions. Of the remaining 53 procedures, 29 underwent either cholangioscopy-directed or cholangioscopy-assisted biopsy, and 24 had both. Cholangioscopy findings consisted of primary sclerosing cholangitis only (n = 18), benign stricture or inflammatory changes (n = 18), bile duct cancer (n = 14), normal (n = 10), pancreatic cancer (n = 5), and other (n = 7). Fifty-eight patients (94%) had follow-up for a mean of 12.4 months (95% confidence interval, 10.1-14.7). Sixteen of 18 (89%) patients with a final diagnosis of malignancy were detected with cholangioscopy. The 2 missed cancers were intrahepatic cholangiocarcinomas. Overall, sensitivity to detect malignancy by cholangioscopy with and without biopsy was 89%, specificity 96%, positive predictive value 89%, and negative predictive value 96%. CONCLUSIONS: Cholangioscopy with and without biopsy is highly accurate in diagnosing and excluding pancreaticobiliary malignancy in patients with indeterminate strictures.

Adult↗
PubMed2006

Pancreatic imaging: current and emerging technologies.

This review discusses the current imaging modalities for the diagnosis and staging of solid and cystic pancreatic lesions and for the assessment of acute and chronic pancreatitis, and the future role of emerging technologies in the management of pancreatic diseases. Multidetector row spiral computed tomography is superior to conventional single-detector row spiral computed tomography in the detection and staging of pancreatic adenocarcinoma. Positron emission tomography is a sensitive but relatively nonspecific diagnostic modality. Positron emission tomography-computed tomography fusion may improve the staging accuracy for pancreatic cancer. Echo-enhanced ultrasound may have an emerging role in evaluating pancreatic masses. Endoscopic ultrasound with fine needle aspiration for cytology is the single best method for diagnosis and staging of nonmetastatic pancreatic cancer with a high accuracy for determining tumor resectability. In acute pancreatitis, a modification of the standard computed tomography severity index, which places greater emphasis on extrapancreatic complications, has shown superior correlation with various patient outcome measures. Endoscopic retrograde cholangiopancreatography is still the test of choice for morphological evaluation of chronic pancreatitis, whereas magnetic resonance cholangiopancreatography offers a noninvasive alternative in selected patients. Endoscopic ultrasound can be useful for detecting early chronic pancreatitis. Secretin-stimulated imaging techniques may eventually provide a noninvasive method of reliably assessing pancreatic exocrine function.

Acute Disease↗
PubMed2006

Is there a role for cholangioscopy in patients with primary sclerosing cholangitis?

OBJECTIVES: Assess the role of cholangioscopy in primary sclerosing cholangitis for 1) detection of cholangiocarcinoma using cholangioscopy-assisted biopsy 2) detection of stones not seen on cholangiography 3) stone removal with cholangioscopy-directed lithotripsy. METHODS: Prospective cohort of consecutive patients referred for cholangioscopy to evaluate dominant strictures or stones. A data collection sheet was employed. Follow-up was by chart review/phone contact. Clinical improvement was defined as resolution of jaundice or > or =50% reduction in pain or cholangitis episodes requiring hospitalization. RESULTS: 41 patients (30M, 11F) had 60 cholangioscopy procedures (55 per oral, 5 percutaneous). 33/41 (80%) patients underwent 44 tissue sampling events. HISTOLOGY: positive for extrahepatic cholangiocarcinoma (N = 1), negative/atypical (N = 31), and inadequate (N = 1). Stones were found in 23/41 (56%) patients, of which 7/23 (30%) were missed on cholangiography and detected only by cholangioscopy. 9/23 (39%) underwent cholangioscopy-directed lithotripsy. Stone clearance: complete (N = 10, 7 by cholangioscopy-directed lithotripsy after failed conventional stone extraction); partial (N = 7); and not attempted (N = 6). Median follow-up was 17.0 months (range 1-56). Clinical improvement was achieved in 25/40 (63%). Eight patients have undergone transplant and cholangiocarcinoma was present in the explant of two at 1 and 12 months post-cholangioscopy, respectively. CONCLUSIONS: This is the first series of patients with primary sclerosing cholangitis undergoing cholangioscopy for the evaluation of dominant strictures and cholangioscopy-directed stone therapy with demonstrable clinical benefits. Stones detected by cholangioscopy were missed by cholangiography in nearly one of three patients. Cholangioscopy-directed lithotripsy may be superior to conventional ERCP for achieving complete stone clearance. Despite the use of cholangioscopy, diagnosis of cholangiocarcinoma remains technically challenging.

Adult↗
PubMed2006

Endoscopic gallbladder stent placement for treatment of symptomatic cholelithiasis in patients with end-stage liver disease.

OBJECTIVES: Symptomatic cholelithiasis is a common disease in the general population with an increased prevalence in patients with cirrhosis. While cholecystectomy is the procedure of choice for the treatment of symptomatic cholelithiasis, cirrhotics have an increased risk of complications associated with this therapy. We have found that placement of an endoscopic gallbladder stent is an alternative, less invasive treatment for cirrhotic patients with symptomatic gallbladder disease and describe our experience here. METHODS: A retrospective medical record review of 23 patients with cirrhosis who underwent endoscopic retrograde cholangiography with gallbladder stent placement for symptomatic gallbladder disease from July 1994 to August 2004. RESULTS: Indications for stent placement included recurrent biliary colic (56.5%), acute calculous cholecystitis (39%), acalculous cholecystitis (8.6%), and gallstone pancreatitis (8.6%). All patients experienced resolution of their symptoms following stent placement. Twenty patients (87%) were asymptomatic from 5 days to 3 years post-procedure until transplantation, death, or end of study period. Nine patients (39%) underwent liver transplantation, 5 days to 34 months after the procedure. Eleven patients are well, with ten patients awaiting liver transplantation. Three patients developed late complications and were treated successfully with antibiotics. CONCLUSION: Endoscopic stenting of the gallbladder may be a potential treatment for symptomatic gallbladder disease in patients with cirrhosis awaiting liver transplantation, considered to be high-risk for cholecystectomy.

Adult↗
PubMed2005

Long-term outcomes of endoluminal gastroplication: a U.S. multicenter trial.

BACKGROUND: Endoluminal gastroplication has shown promise for the treatment of GERD in short-term studies. Until now, long-term outcome data have been lacking. METHODS: A prospective, multicenter trial enrolled 85 patients with GERD to be treated with endoluminal gastroplication. Inclusion criteria were 3 or more heartburn or regurgitation episodes per week, >4.2% time in 24 hours with esophageal pH < 4, and dependency on antisecretory medications. Exclusion criteria were the presence of varices, achalasia, aperistalsis, or previous gastric resection. Patients underwent manometry, 24-hour pH monitoring, and symptom severity scoring before and after the procedure. Patient diaries were used to assess medication use and to estimate annual medication cost. RESULTS: At 1- and 2-year follow-up, patients had significant reductions in median heartburn symptom scores (72 at baseline [interquartile range (IQR) 90-48] vs. 4 at 12 months [IQR 43-0] and 16 at 24 months [IQR 53-3.5]; p < 0.0001 vs. baseline) and median regurgitation symptoms (2 at baseline [IQR 3-1] vs. 0 at 12 months (IQR 1-0) and 1 at 24 months [IQR 1-0]; p < 0.0001 vs. baseline). Of all patients, 59% and 52% showed heartburn symptom resolution at 12 and 24 months, respectively ( p < 0.0001 vs. baseline). Also, 83% and 77% had regurgitation symptom resolution at 12 and 24 months, respectively (p < 0.0001 vs. baseline). Proton pump inhibitor use also was significantly reduced at 12 and 24 months after the procedure. At 2-year follow-up, median annualized medication costs were reduced by 88% (1381 US dollars) (p < 0.0001). Endoluminal gastroplication significantly reduced the duration and the number of episodes of esophageal acid exposure (p < 0.0001 vs. baseline). Only 7 patients experienced adverse events. CONCLUSIONS: Endoscopic gastroplication is safe and effective, and is associated with symptom reductions in patients with GERD for at least 24 months.

Circadian Rhythm↗
PubMed2005

Endoscopic approaches to the treatment of gastroesophageal reflux disease.

PURPOSE OF REVIEW: Endoscopic therapies for gastroesophageal reflux disease represent a minimally invasive alternative to medical or surgical treatment. These devices include suturing, radiofrequency energy, and bulking agent technologies. Research into the use of these technologies in gastroesophageal reflux disease continues to accelerate, and the last 2 years have witnessed significant developments that may affect current and future clinical practice. RECENT FINDINGS: Long-term data from nonrandomized clinical trials have become available in the last 2 years for many gastroesophageal reflux disease endotherapies, providing some insight into their durability. Furthermore, two multicenter and one single-center sham-controlled trials were published recently, allowing comparison between groups. SUMMARY: Although it is premature to propose the superiority of any individual approach, emerging data in this rapidly evolving field may inform current and future directions in the research and treatment of gastroesophageal reflux disease.

Biopolymers↗
PubMed2004

Self-propelling endoscopes.

Self-propelling endoscopes offer exciting possibilities for improving access to colon cancer screening, safety of colonoscopy, and efficiency in endoscopy. From an operational perspective, efficiency in endoscopy may be increased or decreased by the introduction of a self-propelling endoscope, depending on the instrument's technical performance characteristics and capabilities, its safety profile, ease of use, the physician time required to review the endoscopic findings, and requirements for sedation, if any. In addition, patient acceptance of such new technology will be a driving force determining its potential for success in the competition for a niche in the diagnostic armamentarium of colon cancer screening.

Colonoscopes↗
PubMed2004

Acute pancreatitis after EUS-guided FNA of solid pancreatic masses: a pooled analysis from EUS centers in the United States.

BACKGROUND: The aim of this study was to determine the frequency and the severity of pancreatitis after EUS-guided FNA of solid pancreatic masses. A survey of centers that offer training in EUS in the United States was conducted. METHODS: A list of centers in which training in EUS is offered was obtained from the Web site of the American Society for Gastrointestinal Endoscopy. Designated program directors were contacted via e-mail. The information requested included the number of EUS-guided FNA procedures performed for solid pancreatic masses, the number of cases of post-procedure pancreatitis, and the method for tracking complications. For each episode of pancreatitis, technical details were obtained about the procedure, including the location of the mass, the type of fine needle used, the number of needle passes, and the nature of the lesion. RESULTS: Nineteen of the 27 programs contacted returned the questionnaire (70%). In total, 4909 EUS-guided FNAs of solid pancreatic masses were performed in these 19 centers over a mean of 4 years (range 11 months to 9 years). Pancreatitis occurred after 14 (0.29%): 95% CI[0.16, 0.48] procedures. At two centers in which data on complications were prospectively collected, the frequency of acute pancreatitis was 0.64%, suggesting that the frequency of pancreatitis in the retrospective cohort (0.26%) was under-reported (p=0.22). The odds that cases of pancreatitis would be reported were 2.45 greater for the prospective compared with the retrospective cohort (95% CI[0.55, 10.98]). The median duration of hospitalization for treatment of pancreatitis was 3 days (range 1-21 days). The pancreatitis was classified as mild in 10 cases, moderate in 3, and severe in one; one death (proximate cause, pulmonary embolism) occurred after the development of pancreatitis in a patient with multiple comorbid conditions. CONCLUSIONS: EUS-guided FNA of solid pancreatic masses is infrequently associated with acute pancreatitis. The procedure appears to be safe when performed by experienced endosonographers. The frequency of post EUS-guided FNA pancreatitis may be underestimated by retrospective analysis.

Acute Disease↗
PubMed2004

Pitfalls of endoscopic ultrasound staging after application of electrocautery.

Patients may be referred for endosonography after endoscopic resection of polyps because of cancer identified in the histologic specimen. To assess the effects of electrocautery-induced tissue changes on tumor staging by endosonography, endosonography findings after endoscopic removal of large polyps were correlated with surgical and endoscopic pathology. Endosonography findings revealed irregular and thickened wall layers, especially in the muscularis propria with pseudopod extensions. Five of 7 patients had evidence of cancer in the endoscopic specimen. However, no residual tumor was found in the surgically resected bowel (2 patients) or in subsequent biopsies of the endoscopic resection site (3 patients). In 2 other patients, no cancer was present in the endoscopic specimen, and follow-up biopsies of the endoscopic resection site were all benign. Electrocautery-induced inflammatory changes create hypoechoic changes within the gut wall that may mimic tumor invasion. Irregularities in the muscularis propria layer cannot be relied upon to diagnose a T2 or T3 lesion by endosonography in this setting. Patients with large polyps greater than 2 cm and other mucosal lesions with malignant potential should undergo endosonography prior to endoscopic resection.

Adenocarcinoma↗