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Biomedical subjects

J A Vennes

Publications and source records attributed to J A Vennes.

At least 19 recordsLinked to original sources

Thermal ablation of the gallbladder.

Gallbladder ablation by means of injection of hot contrast medium was attempted in 13 dogs. Room temperature contrast medium was injected into the gallbladders of two additional dogs (controls). After midline laparotomy was performed to expose the gallbladder, temperature probes were placed in the liver adjacent to the gallbladder, and on the surface and in the lumen of the gallbladder. A 7-F catheter with multiple side holes was placed into the gallbladder. The cystic duct was clamped during the procedure. After injection of boiling contrast medium, the mean temperature in the gallbladder lumen was 80 degrees C; in the adjacent liver, 43.5 degrees C; and on the gallbladder surface, 45.8 degrees C. After the procedure, the cystic duct was unclamped, temperature probes and catheter were removed, and the laparotomy was closed in standard fashion. In the hot contrast medium group, one dog each was sacrificed at 2, 4, 8, and 12 weeks, and at 6 months. Six animals were sacrificed at 1 year. The gallbladder was completely ablated in 11 of 13 animals in the hot contrast medium group. One dog was sacrificed at 8 days because of bile leakage, and another was sacrificed at 17 days because of gallbladder rupture. The two control animals were sacrificed at 12 and 13 weeks, and their gallbladders were normal at that time.

Animals

A new mechanical lithotripter for the treatment of large common bile duct stones.

A prospective uncontrolled multi-center trial of a prototype mechanical lithotripter was performed in 30 patients with common bile duct calculi. Standard endoscopic sphincterotomy had failed to remove all stones, primarily because of large size (26 patients). Stone size ranged from 13 to 35 mm. Forty-three of 45 stones (97%) were successfully captured, fragmented, and extracted with this newly designed mechanical lithotripter. The overall success rate of 93% using this simple and inexpensive modality compares favorably with other methods under investigation for the treatment of common bile duct stones not amenable to routine endoscopic measures.

Duodenoscopy

In vivo evaluation of monopolar versus bipolar electrosurgical polypectomy snares.

The energy required and tissue damage in bipolar and monopolar polypectomy snares were compared in a canine model. The bipolar snare required an average of 34 joules of energy, whereas the monopolar snare required 228 joules to cut the same diameter of gastric mucosa tended into a polypoid structure (p = 0.0005). The reduced energy delivered to the tissue from the bipolar procedure resulted in only 32% average depth of damage to the underlying gastric wall, whereas the monopolar procedure caused an average 69% (p = 0.001). Surgically created polyps required 247 joules and 69 joules for corresponding monopolar and bipolar polypectomy (p = 0.001). The decreased energy required and the correspondingly reduced damage caused to the underlying bowel wall by the bipolar snare should reduce the incidence of perforation and post-polypectomy syndrome. The bipolar snare completes a local circuit about the snare, eliminating the return electrode and, consequently, the possibility of any return electrode burns. The bipolar snare thus provides an added safety margin during polypectomy.

Animals

Effects of biliary obstruction on hepatic clearance of bacteria.

High surgical mortality in patients with obstructive jaundice and sepsis have been attributed to reticuloendothelial system (RES) depression. The purpose of this study was to clarify the effects of mechanical biliary obstruction on RES clearance of pathogenic bacteria by comparing the phagocytic index (K) with the directly measured hepatic uptake of indium 111-labeled bacteria injected into the portal vein of normal dogs and dogs with partial (PBO) or complete biliary obstruction (CBO). No significant difference was observed between the K in normal dogs (0.19 +/- 0.08; n = 6) and that in dogs with PBO (0.24 +/- 0.06; n = 5) or CBO (0.21 +/- 0.03; n = 4). There was no significant difference in uptake of radiolabel by the liver among the three groups of dogs. In our model, biliary obstruction had no effect on hepatic RES function and may not represent a significant determinant of mortality in patients with obstructive jaundice.

Alkaline Phosphatase

Choledochal cyst: findings on cholangiopancreatography with emphasis on ectasia of the common channel.

Choledochal cyst is a congenital malformation of the biliary tree that is unusual but by no means rare. During a 13-year period, we encountered eight patients with choledochal cysts who were evaluated with cholangiopancreatography. All of our cases showed an anomalous union of the pancreatic duct and common bile duct, resulting in a long common channel. Review of cholangiopancreatograms also showed ectasia of the common channel in six of the eight patients. Mean length of the common channel, corrected for magnification, was 26 mm (normal, less than 15 mm). The mean corrected diameter of the common channel was 7 mm (normal, 3-5 mm). We conclude that ectasia of the common channel is an important additional radiographic observation in the diagnosis of choledochal cyst. This observation has not been emphasized before.

Adolescent

Pancreatic pseudocysts: clinical and endoscopic experience.

Records of 51 patients with proven pancreatic pseudocyst (PC) were retrospectively reviewed to assess clinical and endoscopic variables. Thirty-nine had surgery after preoperative endoscopic retrograde cholangiopancreatography (ERCP), six patients had ERCP only, and six patients had surgery without prior ERCP. Forty-two pancreatograms were obtained, and all were abnormal. PC communication with the pancreatic duct was present in 29 and ductal obstruction downstream from the PC was shown in 11 studies. Thirty-five cholangiograms were obtained and 19 were abnormal, including ductal narrowing in 16 and biliary calculi in three. PC contents were cultured intraoperatively in 29 patients, and 17 were positive. PC infection was highly correlated with the incidence of recurrent hospitalizations and with PC recurrence. PC infection did not occur significantly more often in patients with communicating PC or in those with preoperative ERCP. Factors that did not influence outcome included PC size, multiplicity, anatomic location, and PC communication with the pancreatic duct. Results from both ERCP and culture of PC contents add significantly to our knowledge of PC disease.

Adult

Spontaneous passage of glass beads from the canine gallbladder: facilitation by sphincterotomy.

To investigate the mechanism by which ablation of the sphincter of Oddi prevents gallstone formation, we assessed passage of glass beads out of the gallbladders of dogs with sphincterotomy and sham sphincterotomy. One month after bead implantation, dogs with an intact sphincter passed 52%, 26%, 22%, 10%, 0%, and 0% of beads with diameters of 2, 3, 4, 5, 6, and 8 mm, respectively. For the same respective bead diameters, dogs with a sphincterotomy passed 90%, 90%, 88%, 75%, 75%, and 42% of beads (p less than 0.05 for all bead diameters). No beads were in the common bile duct of any dog. In separate dogs studied by cholescintigraphy, sphincterotomy significantly increased gallbladder ejection fraction from 0.46 to 0.76 (p less than 0.01). In addition, sphincterotomy significantly lowered resting gallbladder volume from 24.4 to 15.8 ml (p less than 0.025) and lowered cholecystokinin-stimulated gallbladder volume from 13.3 to 5.9 ml (p less than 0.025). These data indicate that even with an intact sphincter, small solids can pass from the gallbladder and into the duodenum. Sphincterotomy facilitates passage of solids, apparently by general improvement in gallbladder emptying. Facilitated passage of crystals, microliths, or small stones seems the most likely explanation for prevention of gallstone formation by sphincterotomy.

Animals

Partial biliary obstruction caused by chronic pancreatitis. An appraisal of indications for surgical biliary drainage.

This paper presents a retrospective review of 38 patients with intrapancreatic bile duct strictures secondary to chronic alcoholic pancreatitis. The strictures were identified by endoscopic retrograde cholangiopancreatography (ERCP). All patients with pancreatic cancer and gallstone pancreatitis were excluded. The mean alkaline phosphatase and total bilirubin values were 344 +/- 57 IU/dl and 4.4 +/- 0.7 mg/dl, respectively. The mean stricture length was 3.9 +/- 0.5 cm, and the mean common bile duct (CBD) diameter was 1.8 +/- 0.2 cm. The degree of bilirubin and alkaline phosphatase elevation did not correlate with stricture length or the severity of bile duct dilatation. Eighteen of the 38 patients received surgical biliary drainage (BD) as part of their initial therapy, and 20 patients did not. Liver function tests, intrapancreatic stricture length, and the degree of proximal CBD dilation were comparable in these two groups. Patients not undergoing BD did well clinically as only one patient required BD over an average follow-up period of 3.8 years. In conclusion, bypass of these strictures is usually unnecessary, and most patients may be safely treated without operation.

Adult

Effect of bombesin and gastrin-releasing peptide on canine sphincter of Oddi.

This study reports the effects of bombesin and gastrin-releasing peptide (GRP) on the canine sphincter of Oddi using a method that allows repeated cannulation of the biliary sphincter in the unanesthetized animal through a Thomas cannula placed opposite the biliary papilla. Immediately after intravenous administration of bombesin or GRP, phasic sphincter contractions disappeared, basal sphincter pressures fell, and common bile duct pressures rose. Because bombesin releases cholecystokinin (CCK) and CCK resulted in a similar pattern to that of bombesin, the bombesin effect on the sphincter of Oddi may have been secondary to CCK's effect on the sphincter. To test if the bombesin effect on the sphincter of Oddi was due to the release of CCK, we blocked CCK release by administration of somatostatin, having first established that somatostatin blocked endogenous CCK release in our animal model by use of an intraduodenal infusion of lipid. Exogenous administration of bombesin failed to alter sphincter of Oddi or common bile duct pressures in dogs treated with somatostatin. Somatostatin did not, however, block CCK's effect on gallbladder contraction, since exogenous administration of CCK after somatostatin injection resulted in the pressure changes in the biliary tree typical of CCK-induced gallbladder contraction. Thus bombesin administration appears to result in sphincter relaxation and gallbladder contraction by the release of endogenous CCK rather than by a direct effect. The increase in common bile duct pressures was due to gallbladder contraction, since this rise in pressure was abolished by cholecystectomy. The peptide effect on sphincter contraction and basal sphincter pressure were unaffected by cholecystectomy.

Ampulla of Vater

Pseudomonas infection of the biliary system resulting from use of a contaminated endoscope.

Pseudomonas aeruginosa was present in bile cultures from 10 patients who had undergone previous endoscopic retrograde cholangiopancreatography in 1984. After environmental cultures and review of instrument disinfection, we traced the infections to a single endoscope contaminated with P. aeruginosa, serotype 10. Although the instrument had been cleaned repeatedly with an automatic endoscope cleaning machine, P. aeruginosa survived on residual moisture left in the channels of the endoscope. Contamination ended only after we began to manually suction alcohol through the endoscope before air drying. In 5 of 10 patients, P. aeruginosa caused clinical infections including gangrenous cholecystitis, abscesses, and death. We could identify no factor that distinguished symptomatic from asymptomatic patients. In asymptomatic patients, P. aeruginosa was recovered from gallbladder bile up to 2 mo after endoscopic retrograde cholangiopancreatography. As this P. aeruginosa epidemic was discovered retrospectively because we monitor bile cultures, we advocate this practice as part of endoscopic retrograde cholangiopancreatography procedures.

Bile

Endoscopic sphincterotomy for suspected dysfunction of the sphincter of Oddi.

Fifty-one patients who underwent endoscopic sphincterotomy for suspected dysfunction of the sphincter of Oddi were evaluated retrospectively. The procedure resulted in complete abolition of pain allowing discontinuation of analgesics in 31 of the 46 patients available for follow-up. Patients with a dilated bile duct and delayed drainage of contrast material as demonstrated at endoscopic retrograde cholangiopancreatography (ERCP) had a more favorable response to sphincterotomy than those with normal ductal findings (p = 0.01). There was a higher complication rate in those without ductal dilation and delayed drainage compared to those with these ERCP abnormalities (p = 0.03). Sphincter of Oddi manometry was obtained in 29 patients prior to sphincterotomy; 24 were available for follow-up. A favorable outcome for sphincterotomy did not correlate with manometric assessment, particularly in patients with an abnormal ductal system.

Adult

Gastrinoma associated with common bile duct obstruction and the ectopic production of ACTH.

A case of adrenocortical hyperfunction due to ectopic production of ACTH by a gastrin-producing tumor of the pancreas is described. Cushing's syndrome preceded the appearance of the overt Zollinger-Ellison syndrome by 2 years and was treated by bilateral adrenalectomy. The Zollinger-Ellison syndrome was initially treated with cimetidine, which successfully reduced the secretion of gastric acid. Because the pancreatic gastrinoma continued to grow, causing obstruction of the common bile duct, biliary diversion and total gastrectomy were performed. There is evidence that the pancreatic gastrinoma was the source of the ectopic production of ACTH and possibly secretion. The role of Histamine-2 blocking agents as therapy in the Zollinger-Ellison syndrome is discussed.

Adrenocorticotropic Hormone

Significance of the nonopacified gallbladder in endoscopic retrograde cholangiography.

Failure to visualize the cystic duct and gallbladder during endoscopic retrograde cholangiography, while obtaining satisfactory opacification of the rest of the biliary system, is a radiographic sign of undetermined meaning. The diagnostic implication of this finding was analyzed in 63 patients with pathologically proven diagnoses. One patient was normal at surgery. Three groups of abnormal patients had: (1) obstructing lesions of the distal common bile duct (35 patients); (2) primary lesions of the cystic duct or gallbladder (19 patients); or (3) obstructing lesions about the common hepatic/cystic duct junction (8 patients). The results indicate that obstructing lesions of the distal common bile duct may cause stasis of bile within the biliary system, increased biliary pressure, and sludge formation that prevent the flow of contrast material through the cystic duct and into the gallbladder, which can cause nonopacification. If the extrahepatic biliary system is of normal caliber without evidence of an obstructing process, nonfilling of the cystic duct and gallbladder is highly predictive of pathology.

Biliary Tract Diseases

The normal cholangiogram.

This paper describes the measurements of the normal cholangiogram as demonstrated by endoscopic retrograde cholangiopancreatography. Two groups of patients were studied. There were 49 patients who had normal livers and no evidence of biliary tract disease. In addition, there were 25 patients with known liver disease and an apparent normal extra-hepatic biliary tract. The extrahepatic bile duct was measured in three regions: (1) the common hepatic duct (above the cystic duct and below the bifurcation); (2) the prepancreatic portion (below the cystic duct and above the pancreas); and (3) the interpancreatic portion (bile duct within the pancreas). These measurements ranged from 2.1 to 9.2 mm. Although the common bile ducts were generally quite uniform in caliber, there were instances where each portion was the largest diameter in an individual case. There was slight increase in bile-duct caliber with age. This study showed somewhat smaller measurements than previously reported and may relate to case selection in this or previous studies.

Adolescent