Effect of a novel pancreatic stent design on short-term pancreatic injury in a canine model

Establishment of a multifunctional impact system and a study of a pancreatic trauma model in rats based on controlling the injury area

Background

At present, basic scientific research on pancreatic trauma is rare due to the lack of ideal animal models and modeling equipment for pancreatic trauma. Therefore, we intend to develop a multifunctional impact system with simple operation, diverse impact and accurate measurement and to establish a rat pancreatic trauma model based on injury area control by using the system.

Methods

The impactor was designed based on the convenience of the impact energy acquisition, the diversity of the impact operation, and the precision of the impact strength parameter measurement by the team. The efficacy and stability/repeatability of the impactor were preliminarily evaluated. An impact head with different impact areas (3 cm² and 6 cm²) of the impactor was used to squeeze the rat pancreas in the abdomen to form different injury areas under a pressure of 400 kPa. The efficacy features of this trauma model were evaluated by detecting the outcomes of pathology and biochemistry at 24 h after injury in the two groups. Furthermore, these changes were also evaluated at 6 h, 24 h, 48 h and 72 h after injury in the 3 cm² trauma group.

Result

Multifunctional impactors were successfully explored. The impact force was continuously adjustable with a range of 0-200 kg. The compression and extrusion stress ranges were continuously adjustable from 0 to 100 kg. System adjustment verified that the impactor had fine efficacy (P < 0.05) and stability/repeatability (P > 0.05). Compared with the control group, rats in the pancreatic trauma group with different injury areas exhibited obvious injuries (P < 0.05), and compared with the 3 cm² trauma group, the 6 cm² trauma group exhibited the more severe injury (P < 0.05). After modeling, the injury characteristics at different time points showed stable differences(P < 0.05).

Conclusions

A rat pancreatic trauma model based on injury area control was successfully established using the impactor developed in this study. This model is simple, effective, controllable, and suitable for animal experimental research on pancreatic trauma.

Stent-induced symptomatic pancreatic duct stricture after endoscopic prophylactic pancreatic duct stent placement for the normal pancreas

BACKGROUND/OBJECTIVES

Stent-induced pancreatic duct stricture (SI-PDS) is a complication associated with pancreatic stent placement. However, symptomatic SI-PDS associated with prophylactic pancreatic duct stents has not been sufficiently investigated.

METHODS

We examined the incidence and characteristics of symptomatic SI-PDS in patients who underwent pancreatic duct stent placement to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) between April 2007 and March 2017.

RESULTS

We examined 124 patients with normal pancreases consisting of 75 men and 49 women with a median age of 67.5 years [interquartile range (IQR): 61-74 years]. The median main pancreatic duct (MPD) diameter was 3.3 mm (IQR: 2.6-4.1 mm). The median duration of stent placement was 7 days (IQR: 3-14 days). Spontaneous dislodgment stents were placed in 43.5% of cases (54/124). The diameter of the stent was 5 Fr in 93.5% of cases (116/124) and 7 Fr in 6.5% of cases (8/124). Symptomatic SI-PDS was observed in 2.4% (3/124) of patients overall: 6.5% of patients with an MPD diameter of <3 mm and 0% of patients with an MPD diameter of ≥3 mm. Univariate analysis revealed that an MPD diameter <3 mm was a significant factor for symptomatic SI-PDS (p = 0.048). All cases of symptomatic SI-PDS improved with endoscopic treatment.

CONCLUSIONS

Symptomatic SI-PDS occurred in 2.4% of patients who underwent prophylactic pancreatic duct stent placement for normal pancreases. Patients with an MPD diameter of <3 mm may be susceptible to symptomatic SI-PDS.

[Endoscopic pancreatic stenting in pancreatic fistulas management]

AIM

To present 18-year experience of endoscopic transpapillary stenting in patients with pancreatic fistula.

MATERIAL AND METHODS

The study included 48 patients with pancreatic fistula resistant to conservative management. Pancreatic stenting was successful in 32 (66.7%) patients. In 30 (93.8%) of them stenting appeared as the final stage of pancreatic fistula treatment.

RESULTS

Inclidence of complications after endoscopic treatment was 4.2%. We evaluated long-term results in 23 cases within 8-184 months. There were good results in 21 (91.3%) cases and satisfactory - in 2 (8.7%) cases. We had not unsatisfactory results in our experience.

Pancreatic Endotherapy for Chronic Pancreatitis

Extracorporeal shock wave lithotripsy is recommended as the first-line therapy for large (>5-mm) obstructive pancreatic ductal stones. Dominant pancreatic duct strictures should be initially managed with a wide-bore single plastic stent with 3 monthly exchanges for a year, even in asymptomatic patients. Recent studies have evaluated multiple plastic and self-expanding covered metal stents for refractory pancreatic ductal stricture. Pancreatic pseudocysts should be treated endoscopically with or without endoscopic ultrasound guidance.

Endoscopic prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is not an uncommon adverse event but may be an avoidable complication. Although pancreatitis of severe grade is reported in 0.1%-0.5% of ERCP patients, a serious clinical course may be lethal. For prevention of severe PEP, patient risk stratification, appropriate selection of patients using noninvasive diagnostic imaging methods such as magnetic resonance cholangiopancreatography or endoscopic ultrasonography (EUS), and avoidance of unnecessary invasive procedures, are important measures to be taken before any procedure. Pharmacological prevention is also commonly attempted but is usually ineffective. No ideal agent has not yet been found and the available data conflict. Currently, rectal non-steroidal anti-inflammatory drugs are used to prevent PEP in high-risk patients, but additional studies using larger numbers of subjects are necessary to confirm any prophylactic effect. In this review, we focus on endoscopic procedures seeking to prevent or decrease the severity of PEP. Among various cannulation methods, wire-guided cannulation, precut fistulotomy, and transpancreatic septostomy are reviewed. Prophylactic pancreatic stent placement, which is the best-known prophylactic method, is reviewed with reference to the ideal stent type, adequate duration of stent placement, and stent-related complications. Finally, we comment on other treatment alternatives, and make the point that further advances in EUS-guided techniques may afford useful PEP prophylaxis.

Endoscopic therapy for chronic pancreatitis

PURPOSE OF REVIEW

To summarize recent data on techniques, efficacy and complications of endoscopic management of chronic pancreatitis.

RECENT FINDINGS

Extracorporeal shock wave lithotripsy with or without endoscopic retrograde cholangiopancreatography is the first-line treatment for large painful obstructive pancreatic duct calculi. Use of preextracorporeal shock wave lithotripsy secretin could result in better stone clearance. The first-line treatment for dominant pancreatic duct strictures is placement of a single 10-Fr polyethylene stent with planned exchanges every 3 months until 1 year. Other endoscopic approaches that have shown good efficacy include placement of simultaneous multiple plastic stents and fully covered self-expanding metallic stents. Endoscopic options to treat chronic pancreatitis-associated benign biliary strictures include single and simultaneous multiple plastic stenting and fully covered self-expanding metallic stents. The European Society of Gastrointestinal Endoscopy recommends multiple plastic stenting for such strictures, although fully covered self-expanding metallic stents should be currently used under research settings. Endoscopic ultrasonography-guided cholangiopancreatography and pancreatobiliary drainage is an evolving option for chronic pancreatitis-related ductal obstruction after failed endoscopic retrograde cholangiopancreatography. Recent data have supported the safety and efficacy of endotherapy for chronic pancreatitis in children.

SUMMARY

Endotherapy is the first line of management in chronic pancreatitis with symptomatic pancreatobiliary ductal obstruction. Further studies are required in certain key areas such as use of fully covered self-expanding metallic stents for pancreatic ductal and biliary strictures and endoscopic ultrasonography-guided pancreatobiliary drainage after failed endoscopic retrograde cholangiopancreatography.

Endoscopic therapy for pancreatic duct leaks and disruptions

Pancreatitis, whether acute or chronic, can lead to a plethora of complications, such as fluid collections, pseudocysts, fistulas, and necrosis, all of which are secondary to leakage of secretions from the pancreatic ductal system. Partial and side branch duct disruptions can be managed successfully by transpapillary pancreatic duct stent placement, whereas patients with disconnected pancreatic duct syndrome require more complex endoscopic interventions or multidisciplinary care for optimal treatment outcomes. This review discusses the current status of endoscopic management of pancreatic duct leaks and emerging concepts for the treatment of disconnected pancreatic duct syndrome.

Pancreatic and biliary stents

Biliary and pancreatic stents are used in a variety of benign and malignant conditions including strictures and leaks and in the prevention of post-ERCP pancreatitis.Both plastic and metal stents are safe, effective, and easy to use. SEMSs have traditionally been used for inoperable malignant disease. Covered SEMSs are now being evaluated for use in benign disease. Increasing the duration of patency of both plastic and metal stents remains an important area for future research.

Treatment of pancreatic strictures

The diagnosis and treatment of patients with pancreatic strictures presents a multitude of clinical challenges. The etiology of pancreatic strictures is varied, including benign strictures subsequent to acute pancreatitis, trauma, postsurgical, post-endoscopic retrograde cholangiopancreatography (ERCP), and malignancy. Patients with strictures usually present with symptoms of recurrent pancreatitis, abdominal pain, weight loss, and/or steatorrhea. The absence of a prior history of pancreatitis or surgery increases the likelihood of malignancy. High-quality imaging studies of the pancreas, CT, MRI/magnetic resonance cholangiopancreatography, or endoscopic ultrasound (EUS) scanning are utilized for better definition. Imaging detects an associated mass and/or demonstrates the ductal anatomy. Invasive procedures such as ERCP are performed to better define the causal relationships of the patient's symptoms or to obtain tissue diagnosis. Treatment goals include ameliorating symptoms, dilating the stricture, and ruling out cancer. The risk of malignancy underlies much of the intervention, which includes serology, cytologic analysis, and serial imaging. EUS has become the procedure of choice to rule out a mass, to evaluate the parenchyma for evidence of chronic pancreatitis, and to obtain fine-needle biopsies for tissue confirmation. In symptomatic patients or patients with indeterminate strictures, ERCP is used for direct pancreatography, tissue acquisition, and endoscopic treatment. Endotherapy includes sphincterotomy, dilation, and stenting to provide drainage. We view ERCP as the optimal first-line treatment modality. ERCP offers the potential of curative treatment and is less invasive than surgery, especially as some patients' symptoms are not severe enough to justify surgery. If patients do not experience relief of symptoms after several sessions of endoscopic therapy, surgery is the logical next step for definitive, long-term treatment.

Pancreatic stents

Use of stents in the pancreas has been confined and limited to referral centers that specialize in the treatment of patients with severe pancreatitis and acute relapsing pancreatitis. With therapeutic development in endoscopic treatment of pancreatic diseases and a better understanding of the cause and prevention of ERCP related complications, the use of stents has been extended to transmural drainage of pancreatic fluid collection or of pancreatic ducts has well as to prophylaxis of post-ERCP pancreatitis. As a result, indication for pancreatic stenting and the kind of stents to be used as well as the followup after placement varies. This article reviews the major indication for pancreatic stent placement and focuses on the choice of stent, technique of implantation and followup.

Endoscopic stenting for palliation of malignant biliary obstruction

Malignant biliary obstruction results in jaundice, often with symptoms that decrease the quality of life. Biliary stent placement has largely supplanted surgical bypass for palliation of malignant biliary obstruction. Traditional rigid plastic stents are commonly used, inexpensive and easily removed, although with limited duration of stent patency. Self-expandable metal stents (SEMS) attain larger luminal diameters and provide longer patency than traditional rigid plastic stents in patients with distal bile duct obstruction. SEMS are composed of a variety of metals and can be uncoated, partially covered, or fully covered. Data do not support a prolongation of patency with covered SEMS for distal obstruction, although they have the potential for removability. The data to support SEMS for palliation of hilar biliary obstruction are not as convincing and reintervention for stent occlusion can be difficult. In this article, the design and performance of expandable metal stents for treatment of malignant biliary obstruction will be reviewed.

Endoscopic pancreatic duct stent placement for inflammatory pancreatic diseases

The role of endoscopic therapy in the management of pancreatic diseases is continuously evolving; at present most pathological conditions of the pancreas are successfully treated by endoscopic retrograde cholangio-pancreatography (ERCP) or endoscopic ultrasound (EUS), or both. Endoscopic placement of stents has played and still plays a major role in the treatment of chronic pancreatitis, pseudocysts, pancreas divisum, main pancreatic duct injuries, pancreatic fistulae, complications of acute pancreatitis, recurrent idiopathic pancreatitis, and in the prevention of post-ERCP pancreatitis. These stents are currently routinely placed to reduce intraductal hypertension, bypass obstructing stones, restore lumen patency in cases with dominant, symptomatic strictures, seal main pancreatic duct disruption, drain pseudocysts or fluid collections, treat symptomatic major or minor papilla sphincter stenosis, and prevent procedure-induced acute pancreatitis. The present review aims at updating and discussing techniques, indications, and results of endoscopic pancreatic duct stent placement in acute and chronic inflammatory diseases of the pancreas.

Endoscopic pancreatic duct stent placement for inflammatory pancreatic diseases

The role of endoscopic therapy in the management of pancreatic diseases is continuously evolving; at present most pathological conditions of the pancreas are successfully treated by endoscopic retrograde cholangio-pancreatography (ERCP) or endoscopic ultrasound (EUS), or both. Endoscopic placement of stents has played and still plays a major role in the treatment of chronic pancreatitis, pseudocysts, pancreas divisum, main pancreatic duct injuries, pancreatic fistulae, complications of acute pancreatitis, recurrent idiopathic pancreatitis, and in the prevention of post-ERCP pancreatitis. These stents are currently routinely placed to reduce intraductal hypertension, bypass obstructing stones, restore lumen patency in cases with dominant, symptomatic strictures, seal main pancreatic duct disruption, drain pseudocysts or fluid collections, treat symptomatic major or minor papilla sphincter stenosis, and prevent procedure-induced acute pancreatitis. The present review aims at updating and discussing techniques, indications, and results of endoscopic pancreatic duct stent placement in acute and chronic inflammatory diseases of the pancreas.

The role of endoscopy in the therapy of chronic pancreatitis

Almost all the therapeutic efforts in the treatment of chronic pancreatitis are directed towards pain control. Endoscopic techniques available for this purpose are endoscopic retrograde cholangiopancreatography (combined or not with extracorporeal shock wave lithotripsy) and endoscopic ultrasound. Pancreatic stones and strictures, pancreatic pseudocysts, and common bile duct strictures complicating chronic pancreatitis can be treated by endoscopy. The development of endoscopic ultrasound extended the possibilities in the treatment of pancreatic pseudocysts and main pancreatic duct drainage. Endoscopy is considered the first-line treatment in chronic pancreatitis and can be useful also as a 'bridge to surgery'. In fact the endoscopic approach to chronic pancreatitis can predict the response to surgical therapy as a definitive treatment. Medical, endoscopic and surgical methods for the management of chronic pancreatitis should all be considered in decision-making, and the best treatment should be chosen case by case and according to the local expertise.

Prophylaxis of post-endoscopic retrograde cholangiopancreatography pancreatitis by an endoscopic pancreatic spontaneous dislodgement stent

BACKGROUND & AIMS

Pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP) is the most common and potentially serious complication of ERCP. The frequency of post-ERCP pancreatitis generally is reported to be between 1% and 9%. One cause of pancreatitis is retention of pancreatic juice resulting from papilledema after the procedure. We conducted a randomized controlled multicenter study to evaluate whether placement of a temporary pancreatic stent designed for spontaneous dislodgement prevents post-ERCP pancreatitis.

METHODS

The subjects were 201 consecutive patients who underwent ERCP. The patients were randomized into the stent placement group (S group = 98) or the nonstent placement group (nS group = 103). The stent used was 5F in diameter, 3 cm in length, straight, and unflanged inside.

RESULTS

Stents were placed successfully in 96% of the S group, and spontaneous stent dislodgment was recognized in 95.7% of those. The mean duration to dislodgment was 2 days, and there were no severe complications. The overall frequency of post-ERCP pancreatitis was 8.5%. The frequency of post-ERCP pancreatitis in the S and nS groups was 3.2% and 13.6%, respectively, showing a significantly lower frequency in the S group (P = .019). The mean increase in amylase level in the pancreatitis patients was significantly higher in the nS group (P = .014).

CONCLUSIONS

The randomized controlled multicenter trial showed that placement of a pancreatic spontaneous dislodgment stent significantly reduces post-ERCP pancreatitis.

Pancreatic stents for prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis

Placement of pancreatic stents is a relatively new and increasingly adopted approach to reduce the risk of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis. Evidence for the efficacy of pancreatic stents in reducing post-ERCP pancreatitis continues to accumulate. Routine use of pancreatic stents in high-risk cases at advanced centers has changed the complexion of ERCP, reducing the incidence and severity of post-ERCP pancreatitis to a more acceptable level, and eliminating some of the fear factor surrounding previously prohibitively risky settings, such as treatment of sphincter of Oddi dysfunction (SOD). On the other hand, the adoption of prophylactic pancreatic stenting into some practices has been sporadic. Problems with pancreatic stent placement include technical difficulty with placement, need for follow-up evaluation to ensure passage or removal, and potential for inducing pancreatic ductal injury. There remain many challenges and unanswered questions which will be addressed in this review, including which patients are at risk for post-ERCP pancreatitis, how might pancreatic stents reduce risk, what is the evidence supporting efficacy of pancreatic stenting in reducing risk; and based on those data, which ERCPs are at sufficiently high risk to warrant a stent; at what point in an ERCP should a pancreatic stent be placed; how long pancreatic stents need to remain in place to be effective, the risk of inducing pancreatic duct injury by placement of a stent; the frequency and consequences of failure at attempted stent placement, and effectiveness of pancreatic stent placement in the hands of those with limited experience. Current recommendations for use of pancreatic stents and areas requiring further investigation are discussed.