A new pulsed Doppler catheter has been developed for use during gastrointestinal fiberendoscopy. Modern gastrointestinal endoscopy allows inspection of the wall of the entire esophagus, stomach, duodenum, and colon. Diagnosis is performed by inspecting the surface of the mucosa, biopsy, and cytology. However, it is not possible to determine the characteristics of the blood vessels of the wall beneath the mucosa with available techniques. We have developed a Doppler system which is miniature and can be passed down the biopsy channel of standard fiberendoscopes. This 8 MHz device incorporates range limiting to select the depth of interrogation by Doppler. The length of the probe is 2 m, and the diameter is 1.8 mm. This device has been tested in animal studies for efficacy and safety and is now being tested clinically in patients. The probe has been tested for two indications: the detection of the retroduodenal artery prior to endoscopic papillotomy for retained bile duct stones (90 patients); and the detection of flow in esophageal varices before and after endoscopic sclerotherapy (33 patients). Preliminary results are encouraging and suggest that this device can give information about submucosal blood vessels which cannot be detected using other methods.

Flexible fiberoptic endoscopes permit the physician to inspect the mucosal surface of the upper gastrointestinal tract and colon. However, this visual inspection provides little information about the underlying vascular supply to the intestinal wall. We tested the hypothesis that a Doppler probe could be constructed small enough to pass through the biopsy channel of a fiber endoscope and be used with it while performing endoscopy. The purpose would be to determine the location of patent arteries or veins, determine the magnitude and waveforms of the velocity in them, and estimate their contribution or potential contribution to intestinal bleeding. For this purpose, a miniature catheter probe (1.8 mm O.D. and 2 m in length) and an electronic range limited pulsed Doppler unit were developed. This probe and unit were studied in a series of 13 dogs to determine efficacy of detecting arterial and venous flow and to test the safety of the device. The duodenum was surgically exposed and opened in the region of the common bile duct (CBD). Arteries and veins surrounding the CBD were studied. Particular attention was directed to arterial structures which clinically pose a risk of bleeding when performing endoscopic papillotomy, a therapeutic technique in which the papilla of Vater is cut to release bile duct stones. The results of the study revealed that the probe could indeed detect arterial and venous structures accurately. There was no evidence that the probe produced any injury to the common bile duct or pancreas by histological or serum amylase studies and the device was determined safe and suitable for clinical evaluation.

The deleterious effects of aspirin on gastric mucosa have been well documented in experimental and clinical studies. Prostaglandins offer a potential method by which this injury may be prevented. In these studies, we developed a single-dose endoscopic assay system of aspirin-induced gastric mucosal injury in normal volunteers. With this system, 27 of 30 volunteers (90%) demonstrated severe mucosal injury after ingestion of aspirin. Subsequently, we evaluated whether pretreatment with 15-R-15 methyl prostaglandin E2 prevented severe injury after ingestion of aspirin. Following an initial dose-response study, a double-blind crossover trial was performed using pretreatment with placebo or with 10-micrograms doses of 15-R-15 methyl prostaglandin E2 for 24 h before treatment with aspirin. The results of this trial indicate that prostaglandin pretreatment significantly prevented the occurrence of endoscopically visible severe gastric mucosal injury after single-dose aspirin administration.

A new model of an acute bleeding gastric ulcer with a single bleeding artery in its base has been developed. A suction ulcer defect is created over a large, submucosal artery. Small bleeding marginal vessels are electrocoagulated with a fine-tipped bipolar forceps. The artery in the base of the ulcer is dissected free and then incised longitudinally; brisk bleeding results. A combination of heparin, aspirin, and dipyridamole is used to prevent spontaneous hemostasis. Bleeding from the incised artery of the single vessel ulcer does not decrease over a 10-min interval. No damage to the muscularis externa of the underlying gastric wall results from preparation of the ulcer. The effect of Nd:YAG laser photocoagulation in this new model was compared with the results of photocoagulation in the standard suction ulcer model. In both models the Nd:YAG laser stopped equivalent bleeding from all ulcers. However, there was a marked difference in the depth of tissue injury, with much less damage observed in the single vessel ulcer. This model may provide a better method to assess depth of tissue injury resulting from endoscopic hemostatic techniques.

The advent of flexible fiberoptic endoscopy has stimulated the development of numerous nonsurgical methods to stop bleeding in patients with upper gastrointestinal hemorrhage. Our laboratory has evaluated several of these techniques in studies using standard-sized bleeding canine gastric ulcers. Gas-assisted argon and the neodymium YAG laser photo-coagulation, computer-assisted monopolar and bipolar electrocoagulation, and a new device, the heater probe, are all highly effective for stopping bleeding from this model. Of these, the gas-assisted argon laser produces the least injury to tissue underlying the treated ulcer. A topical hemostatic spray, Flucrylate, proved ineffective in this model. Uncontrolled clinical experience with laser photocoagulation and monopolar electrocoagulation indicates that each stops upper gastrointestinal hemorrhage in more than 90% of treated patients. Based on available experimental and clinical data, we are now undertaking a controlled clinical trial of gas-assisted argon laser photocoagulation in patients with bleeding gastric, stomal, or duodenal ulcers.

Of 29 patients whose endoscopic retrograde cholangiopancreatogram (ERCP) led to a diagnosis of pancreatic neoplasia, 7 presented with steatorrhea. Steatorrhea may be the initial sign of pancreatic malignancy and aggressive evaluation including ERCP should be considered.