Endoscopic sclerotherapy in a rat model of esophageal varices

Experimental model of portal hypertension and esophagogastric varices in minipigs: pressure and endoscopic pilot study

INTRODUCTION

Portal hypertension still represents an important health problem worldwide. In the search for knowledge regarding this syndrome, experimental studies with animal models have proven to be useful to point the direction to be taken in future randomized clinical trials.

PURPOSE

To validate the experimental model of portal hypertension and esophagogastric varices in a medium-sized animal.

METHODS

This study included five minipigs br1. Midline laparotomy with dissection of the portal vein and production of a calibrated stenosis of this vein was performed. Measurement of pressure in the portal venous and digestive endoscopic were performed before and five weeks after the production of a stenosis.

RESULTS

All animals were 8 months old, average weight of 17 ± 2.5 kg. The mean pressure of the portal vein immediately before the partial ligation of the portal vein was 8.9 + 1.6 mm Hg, with 26.6 + 5.4 mm Hg in the second measurement five weeks later (p < 0.05). No gastroesophageal varices or hypertensive portal gastropathy were seen at endoscopy procedures in our sample at any time in the study.

CONCLUSION

Portal vein ligation in minipigs has been validated in the production of portal hypertension, but not in the formation of esophageal varices.

Treatment of achalasia by injection of sclerosant substances: a long-term report

BACKGROUND

Endoscopic sclerotherapy (EST) with ethanolamine oleate (EO) was proposed as a treatment for achalasia, based on the well-known necrotizing effect against the esophageal muscle layers. The aim of this study is to evaluate long-term efficacy of EST.

METHODS

Four consecutive series of patients with achalasia were treated according to different schedules over a period of 20 years, by using EO or polidocanol (PD). The primary outcome was dysphagia relief. Secondary outcomes were lower esophageal sphincter pressure, esophagogram, gastroesophageal reflux and endoscopic ultrasonography (EUS). Patients not responding to EST were treated with 30 mm dilation.

RESULTS

A total of 103 patients completed the treatment. On medium-term evaluation, 75 patients who completed the treatment reached a clinical response labeled as "good," 23 were assessed as "fair," and 5 were assessed as failures. EUS has become a very informative tool to guide the treatment. The overall follow-up lasted for 87.9 ± 66.7 months. Twelve patients experienced a late failure. The cumulative expectancy of being free of recurrence was 90 % at 50 months with EO, but it was only 65 % with PD. Those patients who responded to rescue measures remained in good or fair clinical condition during the remaining follow-up. Young age, PD, and the so-called fusiform pattern on esophagogram proved to be significant predictors of poor prognosis.

CONCLUSION

EST with EO is a promising alternative to classic therapies for achalasia. In contrast, PD-treated patients showed an important trend to fibrosis and clinical recurrence. Dilation seems particularly effective after EST, when this technique has failed.

Simulator training in endoscopic hemostasis

Simulation of upper gastrointestinal (GI) hemorrhage provides the opportunity to practice endoscopic hemostasis without the risk of patient harm and time limitations. Various models have been developed to simulate an acute bleeding source in the upper GI tract to evaluate the feasibility of new endoscopic devices or to practice interventional techniques in a calm and controlled environment. Increasingly available ex vivo models provide this opportunity without the ethical concerns involved with live-animal courses. Validation studies have proven acceptance of ex vivo models and improved clinical performance by repetitive training using these models.

A sclerosant with astringent properties developed in China for oesophageal varices: comparison with ethanolamine oleate and polidocanol

BACKGROUND

Xiao zhi ling (XZL), which consists of Chinese nutgalls and aluminium potassium sulphate, is used as a local injection for the treatment of internal haemorrhoids in China. It is also used for endoscopic sclerotherapy of oesophageal varices. To date, however, it has not been compared with other sclerosants with regard to its safety and efficacy.

METHODS

In the present study, the effect on the endothelium and the haemolytic and thrombosing effects of XZL were compared with those of 5% ethanolamine oleate and 1% polidocanol, using an endothelial cell line and red blood cells taken from rats and the dorsal marginal ear vein of rabbits. In addition, XZL was injected into the area surrounding varices in rats and its efficacy was studied endoscopically and histologically.

RESULTS

Xiao zhi ling reduced the size of varices in rats after causing severe damage in the injected region. Compared with the other two sclerosants, however, XZL had little effect on the endothelium and was the least haemolytic compound. Furthermore, XZL did not cause thrombosis in the injected vein of a rabbit.

CONCLUSIONS

These results suggest that XZL is another type of sclerosant with astringent rather than detergent properties. This compound should be used to treat oesophageal varices by paravariceal injection in smaller doses than 5% ethanolamine oleate and 1% polidocanol.

Esophageal varices in rat models of liver cirrhosis

Animal models resembling the human situation are very useful to investigate human disease. However, there has been no evidence of esophageal varices in rats with liver cirrhosis. In the present study, to determine whether intrahepatic portal hypertension produced by liver cirrhosis induces esophageal varices in rats, the esophagus was examined endoscopically in rat models of liver cirrhosis. All rats given carbon tetrachloride or thioacetamide and six of seven rats given a choline-deficient diet had esophageal varices or venous dilatation after 16 weeks of treatment, although the varices in one rat given carbon tetrachloride and in two rats given a choline-deficient diet were reduced from weeks 16 to 18. These findings suggest that timing is important when studying esophageal varices in rat models of liver cirrhosis. It is concluded that certain models of liver cirrhosis in rats could be used as models of esophageal varices due to intrahepatic portal hypertension.

Hemodynamic studies and esophageal morphometric analyses in portal hypertensive rats with left adrenal vein ligation

BACKGROUND

Despite many attempts to create esophageal varices in experimental animals, most of them have failed. This study investigated whether rats with partial portal vein ligation (PVL) and left adrenal vein ligation (LAL) develop hyperdynamic circulation and dilated esophageal submucosal veins as compared with sham-operated (Sham) plus LAL rats.

METHODS

Two series of experiments were performed to measure (a) systemic and portal hemodynamics and (b) the cross-sectional area of esophageal submucosal veins in Sham, PVL, Sham plus LAL, and PVL plus LAL rats. Hemodynamic studies with a thermodilution technique and esophageal morphometric analyses were performed 14 days after the operation.

RESULTS

PVL rats with or without LAL had a significantly lower mean arterial pressure and systemic vascular resistance accompanied by a significantly cardiac index and portal pressure than Sham rats with or without LAL (P < 0.05). LAL did not induce changes in mean arterial pressure, cardiac index, systemic vascular resistance, hear rate, or portal pressure in either Sham or PVL rats (P > 0.05). The mean cross-sectional area of esophageal submucosal veins in PVL rats with LAL (7340 +/- 833 microns2) was significantly larger than that in Sham rats with LAL (4236 +/- 556 microns2; P < 0.05). There was no significant difference in the mean cross-sectional area of esophageal submucosal veins between PVL and Sham rats without LAL.

CONCLUSIONS

PVL rats with LAL developed hyperdynamic circulation similar to PVL rats without LAL. In addition, PVL plus LAL rats had larger esophageal submucosal veins than Sham plus LAL rats. This study shows that the esophageal submucosal veins of the 14-day partially portal vein-ligated rats with LAL resemble the structural abnormalities observed in human esophageal varices, suggesting that this model could be useful to investigate this entity.