Aortic Customize: an in vivo feasibility study of a percutaneous technique for the repair of aortic aneurysms using injectable elastomer.

OBJECTIVE: This study aimed to test a percutaneous technique for aneurysm-sac filling by means of in situ polymerisation in an in vivo model. DESIGN: Aortic Customize is a new endovascular treatment concept for aortic aneurysms: a non-cross-linked liquid elastomer is injected to fill the aneurysm sac around a balloon-catheter. With this method, a compliant elastomer mould with a patent lumen is created. MATERIAL: The formulation used in the experiments consisted of a two-component addition-cure liquid-silicone formulation, based on vinyl-terminated polydimethylsiloxane (PDMS). METHODS: The concept of aneurysm-sac filling was tested in vivo in porcine experiments (n = 3). RESULTS: In vivo porcine experiments with the sac-filling application showed successful exclusion of the created aneurysms with patent lumens and absence of endoleaks. The aneurysms were excluded successfully in the in vivo model, injecting elastomer through a 7-French catheter, filling up the entire aneurysm sac. CONCLUSIONS: These in vivo experiments demonstrate that the principle of aneurysm-sac filling by means of in situ curing is feasible, excluding the aneurysm and creating a new lumen. Further long-term animal experiments must be done prior to consideration of clinical application.

The effect of inhibition of renin-angiotensin system by valsartan during hypovolemic shock and low flow sigmoideal ischaemia in pigs.

The aim of this experiment was to study the effect of Renin-Angiotensin System (RAS) blockade by means of valsartan on the colonic and systemic circulation in pigs during low flow sigmoideal ischemia in combination with hypovolemic shock. This condition resembles the situation that occurs in patients suffering from a ruptured aneurysm and a compromised colonic circulation. An experimental study in pigs was performed : 6 pigs with low flow sigmoideal ischemia and hypovolemic shock were treated with valsartan and a control group of 5 pigs with low flow sigmoideal ischemia and hypovolemic shock without medical treatment.Valsartan, 3 mg/kg, was administered intravenously. The operation was performed via left sided lumbotomy. The distal aorta was partially occluded to a flow reduction of 30% of the initial value. Hypovolemic shock was induced by withdrawing 20 ml/kg blood in 45 min. Resuscitation with 30 ml/kg haemaccel was iniated after 2 h of shock. The following parameters were measured: blood pressure, cardiac output; hemoglobin, lactate, angiotensin II in mixed venous blood (obtained from pulmonary artery) and in splanchnic blood (obtained from caudal mesenteric vein); and endoluminal pulse oximetry of the sigmoideal mucosa. Statistical analysis was performed by ANOVA and Wilcoxon signed rank test. There was a significant increase of lactate levels both in systemic and splanchnic circulation (P<0.05) in both groups. In the control group, the mean angiotensin II concentrations in the systemic circulation increased, after induction of ischaemia and shock. In the experimental group, the increase in angiotensin concentrations after resuscitation was significantly more prominent. In the colonic circulation, in both groups, there was a significant increase in angiotensin II levels in the splanchnic circulation following ischaemia and reperfusion (P<0.05), but there was no significant difference between the groups. There were no detectable mucosal signals measured by pulse oximetry after induction of shock throughout the experiment, whereas in the experimental group, median mucosal oxygen saturations of 81, 74.5 and 85% were achieved after resuscitation and declamping (P<0.01).In conclusion, angiotensin II inhibition during hypovolemic shock improves the colonic circulation, measured by pulse oximetry. However, other parameters of tissue ischaemia did not improve.