Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia - Online version e-ISSN: 1678-2674

Minipigs maximize efficiency in results, expanding the horizons of medical science in fighting portal hypertension

Experimental surgeries in animal models are essential for the development and refinement of medical procedures that aim to cure diseases, save lives and improve the conditions of patients who need these interventions, as in the case of hepatectomy for the treatment of liver metastasis, reducing mortality from multiple failure of the organ.

Portal hypertension is a health problem that can lead to serious complications, including death from hemorrhagic shock due to rupture of esophagogastric varices. The high incidence and mortality rates of frontal hypertension in patients admitted with upper gastrointestinal bleeding at the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP), where the study was carried out, justify this unprecedented study developed by researchers from São Paulo and Rio de Janeiro, in southeastern Brazil.

The article “Experimental model of portal hypertension and esophagogastric varices in minipigs: pressure and endoscopic pilot study”, published by ACTA Cirúrgica Brasileira (v.37 ed 1, 2022) , sought to validate an unprecedented experimental model in br1 mini pigs, using the partial portal vein ligation technique to induce portal hypertension and esophageal varices described by Jensen et. al. in the 80s.

Image: author.
Figure 1. Calibrated ligation of the portal vein.

In their study, the researchers observed that the technique – already tested in small to medium-sized animals, from rodents to dogs – is undoubtedly effective in producing portal hypertension, but the formation of esophagogastric varices was not observed in all species. Noting that these different results could be related to differences in the portal system of each species, the authors proposed this experiment with five specimens of br1 mini pigs. The portal systems of humans and pigs are similar at a morphological and microstructural level. The minipig has splenic hemodynamics and hepatic metabolism like humans, providing more accurate results.

After a clear and detailed description of the technical procedure to which the models were submitted – including the compliance of these actions with the current legislation on ethics in animal research – the authors concluded that the animal model obtained is valid for the production of portal hypertension in mini pigs br1, but not in the formation of esophageal varices. Thus, the study suggests a starting point for the development of research in this field with medium-sized animals, and indicates the direction to follow in future experiments to obtain a reproducible and reliable model.

Image: author.
Figure 2. Experimental animal (minipig BR-1)

Jensen LS, Krarup N, Larsen JA, Juhl C, Nielsen TH. Effect of acute portal hypertension on hepatosplanchnic hemodynamics and liver function. Scand J Gastroenterol. 1986;22:463-70.

Mariano M. Miniature swine (minipig) in biomedical experimental research: the Minipig br1. Acta Cir Bras. 2003;18(5):387-91.

To read the article, access:

Release for the original article “Experimental model of portal hypertension and esophagogastric varices in minipigs: pressure and endoscopic pilot study” by MALUF FILHO et al. (, published in the vol. 37, no. 1 of ACTA Cirúrgica Brasileira, 2022

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