The endovascular occlusion system for safe and immediate peripheral vessel occlusion during vascular interventions

Assessment of Large Animal Vascular Dimensions for Intra-Aortic Device Research and Development: A Systematic Review

Animal studies are often required to evaluate new cardiovascular medical devices before they reach the market. Moreover, first-generation novel devices including aortic endovascular prostheses and circulatory support devices are often larger than later iterations or tested in a limited range of sizes. One of the challenges in evaluating these devices is finding a model that is both accessible and anatomically similar to humans, as there is a paucity of data on vascular dimensions in large animals. We set out to complete a comprehensive review of available reports on vascular dimensions in swine, ovine, and bovine models, with a particular focus on the descending aorta and ilio-femoral arteries. We searched Embase and MEDLINE databases for reports of descending aorta and peripheral vascular dimension in large animal models. Data from swine, ovine, and bovine models were separated by weight into 3 categories: 40 to 60 kg, 61 to 80 kg, and >80 kg. We also incorporate our computed tomography angiography data from 4 large sheep and 9 calves into this review. Swine, sheep, and calf >80 kg may serve as the best models to maximize aortic diameter resemblance to humans. If device implantation can be achieved in aortas of smaller dimensions, care should be taken to ensure access site suitability such as the common femoral artery in these smaller animals.

Effects of nonselective internal iliac artery angioembolization on pelvic venous flow in the swine model

BACKGROUND

Pelvic angioembolization (AE) is a mainstay in the treatment algorithm for pelvic hemorrhage from pelvic fractures. Nonselective AE refers to embolization of the bilateral internal iliac arteries (IIAs) proximally rather than embolization of their tributaries distally. The aim of this study was to quantify the effect of nonselective pelvic AE on pelvic venous flow in a swine model. We hypothesized that internal iliac vein (IIV) flow following IIA AE is reduced by half.

METHODS

Nine Yorkshire swine underwent nonselective right IIA gelfoam AE, followed by left. Pelvic arterial and venous diameter, velocity, and flow were recorded at baseline, after right IIA AE and after left IIA AE. Linear mixed-effect model and signed rank test were used to evaluate significant changes between the three time points.

RESULTS

Eight swine (77.8 ± 7.1 kg) underwent successful nonselective IIA AE based on achieving arterial resistive index of 1.0. One case was aborted because of technical difficulties. Compared with baseline, right IIV flow rate dropped by 36% ± 29% (p < 0.05) and 54% ± 29% (p < 0.01) following right and left IIA AE, respectively. Right IIA AE had no initial effect on left IIV flow (0.37% ± 99%, p = 0.95). However, after left IIA AE, left IIV flow reduced by 54% ± 27% (p < 0.01). Internal iliac artery AE had no effect on the external iliac arterial or venous flow rates and no effect on inferior vena cava flow rate.

CONCLUSION

The effect of unilateral and bilateral IIA AE on IIV flow appears to be additive. Despite bilateral IIA AE, pelvic venous flow is diminished but not absent. There is abundant collateral circulation between the external and internal iliac vascular systems. Arterial embolization may reduce venous flow and improve on resuscitation efforts in those with unstable pelvic fractures.

LEVEL OF EVIDENCE

Prognostic, level IV.

Design and verification of a shape memory polymer peripheral occlusion device

Shape memory polymer foams have been previously investigated for their safety and efficacy in treating a porcine aneurysm model. Their biocompatibility, rapid thrombus formation, and ability for endovascular catheter-based delivery to a variety of vascular beds makes these foams ideal candidates for use in numerous embolic applications, particularly within the peripheral vasculature. This study sought to investigate the material properties, safety, and efficacy of a shape memory polymer peripheral embolization device in vitro. The material characteristics of the device were analyzed to show tunability of the glass transition temperature (Tg) and the expansion rate of the polymer to ensure adequate time to deliver the device through a catheter prior to excessive foam expansion. Mechanical analysis and flow migration studies were performed to ensure minimal risk of vessel perforation and undesired thromboembolism upon device deployment. The efficacy of the device was verified by performing blood flow studies that established affinity for thrombus formation and blood penetration throughout the foam and by delivery of the device in an ultrasound phantom that demonstrated flow stagnation and diversion of flow to collateral pathways.