Polyurethane foam treatment of type II endoleaks promotes endoleak thrombosis and eliminates intraaneurysmal pressure in the canine model

Abstract

Introduction: The impact on intraaneurysmal pressure of treatments for retrograde-collateral perfusion of AAA after endovascular repair (type II endoleak) has not been evaluated. Using a canine model the effect of polyurethane induced thrombosis of type II endoleaks was measured. Methods: Prosthetic aneurysms with multiple collateral branches (lumbar, caudal mesenteric) were created in the infrarenal aorta of 10 mongrel dogs. Type II endoleaks were generated by excluding the aneurysm from antegrade arterial flow with an impermeable stent graft. Implantation of thrombogenic polyurethane foam (reticulated polycarbonate scaffold, pores 250–600um) was performed in 4 animals via a transfemoral catheter delivery system. In 4 control animals no side branches and no endoleaks were present. Intra-aneurysmal and systemic pressures were measured using a solid-state, strain gauge pressure transducer for 14 days before and 30–90 days after stent graft exclusion. Results: Type II endoleaks generated considerable intraaneurysmal pressurization that was significantly reduced from systemic pressure (P < 0.001)(table). Treatment with polyurethane foam induced thrombosis of the endoleak and feeding arteries in all 4 animals. It resulted in nearly complete elimination of intraaneurysmal pressure (P < 0.001) making it indistinguishable from control aneurysms with no endoleaks (P = NS). Cine MRA, Duplex and angiography documented persistent patency up to the time of euthanasia (mean, 64 days) for untreated type II endoleaks and confirmed thrombosis of polyurethane treated endoleaks. ∗. Systolic pressure∗ Mean pressure∗ Pulse pressure∗ Endoleak patency Patent type II endoleak 0.702 0.784 0.406 Patent Polyurethane treated type II endoleak 0.183 0.142 0.054 Thrombosed Control (no endoleak/no branches) 0.172 0.137 0.089 Thrombosed Systemic pressure 1.0 1.0 1.0 NA p value (patent vs polyurethane treated) <0.001 <0.001 <0.001 <0.001 ∗ All pressures listed were measured after antegrade AAA exclusion and are indexed as a percentage of the systemic pressure. Conclusions: Untreated type II endoleaks result in intraaneurysmal pressures 70–80% of systemic pressure. Thrombosis of endoleaks by polyurethane foam occurs rapidly and results in near abolition of intraaneurysmal pressure.