Endovascular model of abdominal aortic aneurysm induction in swine.

Abdominal aortic aneurysms are among the main causes of death. The high morbidity and mortality associated with aneurysm rupture and repair represents a challenge for surgeons and high risk for patients. Although experimental models are useful to understand, train, and develop new treatment and diagnostic methods for this pathology, animal models developed to date are far from ideal. Animals are either too small and do not represent the pathology of humans, or the procedures employ laparotomy, or the aortic behavior does not resemble that of a true aneurysm. We developed a novel, less invasive and effective method to induce true aortic aneurysms in Large White pigs. Animals were submitted to an endovascular chemical induction using either calcium chloride (25%) or swine pancreatic elastase. Controls were exposed to saline solution. All animals were operated on using the same surgical technique under general anesthesia. They were followed weekly with ultrasound examinations and at 4 weeks the aorta was harvested. Although elastase induced only arterial dilation, imaging, histological, and biomechanical studies of the aorta revealed the formation of true aneurysms in animals exposed to calcium chloride. Aneurysms in the latter group had biomechanical failure properties similar to those of human aneurysms. These findings indicate that the endovascular approach is viable and does not cause retroperitoneal fibrosis.

[Hemodynamic and respiratory changes caused by CO2 laparoscopy in an experimental model of diaphragmatic injury]. / Repercussões respiratórias e hemodinâmicas do pneumoperitônio na lesão do diafragma--estudo experimental.

OBJECTIVE: The objective of this study was to analyze the hemodynamic and respiratory changes caused by CO2 laparoscopy in an experimental model of diaphragmatic injury. METHODS: Fifteen animals chosen at random were submitted to diaphragmatic injury by means of CO2 laparoscopy. Evaluation consisted of drawing blood samples to analyze blood gases, as well as the hemodynamic and respiratory variables. RESULTS: Alterations occurred in APA, CPP, PAO2, ASO2, VSO2. CONCLUSION: We concluded that videolaparoscopy with pneumoperitoneum pressure under 15 mmHg is a safe procedure in patients with diaphragmatic injuries because this pressure level does not cause hemodynamic changes, such as decrease of the cardiac output.

IMPROVED EXPERIMENTAL MODEL TO EVALUATE SUBMUCOSAL INJECTION SOLUTIONS FOR ENDOSCOPIC SUBMUCOSAL DISSECTION.

BACKGROUND: Endoscopic submucosal dissection carries an increased risk of bleeding and perforation. The creation of a long lasting submucosal cushion is essential for the safe and complete removal of the lesion. There is not a suitable experimental model for evaluation of the durability of the cushioning effect of different solutions. AIM: To describe an improved experimental model to evaluate submucosal injection solutions. METHODS: A total of four domestic pigs were employed to evaluate two different submucosal fluid solutions in the gastric submucosa. After midline laparotomy, the anterior gastric wall was incised from the gastric body to the antrum and its mucosal surface was exposed by flipping inside out the incised gastric wall. Two different solutions (10% mannitol and normal saline) were injected in the submucosa of the anterior wall of the distal gastric body. All submucosal cushions were injected until they reach the same size, standardized as 1.0 cm in height and 2.0 cm in diameter. A caliper and a ruler were employed to guarantee accuracy of the measurements. RESULTS: All four animal experiments were completed. All submucosal cushions had the exact same size measured with caliper and a ruler. By using the mannitol solution, the mean duration of the submucosal cushion was longer than the saline solution: 20 and 22 min (mean, 21 min) vs 5 and 6 min (mean, 5.5 min) CONCLUSIONS: This experimental model is simple and evaluate the duration, size, and effect of the submucosal cushion, making it more reliable than other models that employ resected porcine stomachs or endoscopic images in live porcine models.

Venous drainage of the soleus muscle.

Soleus veins have been implicated as the site for deep venous thrombosis initiation. Detailed anatomic knowledge is required for the early diagnosis using non-invasive ultrasound techniques. In the present work, we describe the anatomy of the veins that emerge from the ventral face of the soleus muscle. Twenty-eight soleus muscles were dissected and 543 veins were found. The number of veins per leg ranged from 7 to 38. The distribution of these veins per quadrant ranged from 0 to 12. The greatest number of veins occurred at the superior lateral quadrant. Most soleus veins mainly drained into the posterior tibial and fibular veins. The mean length of the soleus veins ranged from 0.907 to 2.804 cm. We conclude that there is a wide variability in the distribution of soleus veins through the soleus muscle and their quadrants. The majority of the soleus veins drain into the tibial and fibular veins.