Development of portacaval shunts in portal-stenotic cats

Abstract

The goal of the present study was to investigate the formation of portacaval shunts in a new experimental model of chronic portal hypertension, portal vein stenosis in the cat. The procedure gradually occluded the portal vein by use of an Ameroid constrictor around the portal vein. After 4 weeks, the portal vein was completely occluded and portal venous pressure was elevated to 15.6 ± 0.3 mmHg (1 mmHg = 133.3 Pa) (n = 8). The hemodynamic changes did not affect the functional capacity of the liver. Latex injection was used to study the shunts. This revealed the spontaneous development of porta-systemic collaterals in all hypertensive cats, mainly between the gastrosplenic and right gastroepiploic veins and the left renal vein. Fine small branches also drained directly into the cava. The left renal vein was markedly dilated in all cats. Collateral circulation also developed between the inferior vena cava and the inferior mesenteric vein through both left internal testicular and iliolumbar veins. Some branches of the inferior mesenteric vein were connected directly to the cava. Esophageal varices in the mucosa or submucosa were not demonstrated. However, the presence of latex in the pulmonary veins and the visualization of periesophageal collaterals suggest the opening of porta-pulmonary shunts. A constant feature in all cats was the presence of a dilated azygos vein, which drained collaterals retroperitoneally and from the abdominal wall. In conclusion, an experimental model of prehepatic portal hypertension of gradual onset has been developed in cats. The formation of the porta-systemic shunts mimics other animal models and the human form of the disease. It is a homogeneous model and easily reproducible.Key words: portal hypertension, porta-systemic shunts, portal stenosis, Ameroid constrictor, cat.