Abdominal Aortic Endograft Implantation Immediately Induces Vascular Stiffness Gradients That May Promote Adverse Aortic Neck Dilatation: Results of A Porcine Ex Vivo Study

Figure 1.. Experimental setup. (A) Aortic mechanical stimulation. Aortic segments (1) were placed in a vessel chamber (2) and connected to a mock circulation was driven by commercially available pump units (EXCOR 60 mL, Berlin Heart GmbH, Germany) (3). Pressure levels were adjusted via pneumatic “pressure bag” (VBM Medizintechnik, Germany) (4) serving as system afterload and continuously monitored via pressure transducers (5). (B) Axial location of ultrasound measure points. Strain quantifications via ultrasound M-Mode were performed at the stented, unstented, and interface segments of the aortic vessel.

Figure 2.. Aortic endograft implantation immediately induces a permanent axial stiffness gradient at the interface between stented and unstented aorta. (A) Cyclic circumferential strain measured in 2-cm interspaced native porcine abdominal aortic segments under 130/80 mm Hg pulsatile pressurization. The proximal measure point refers to the aortic segment proximally of the renal arteries. This also corresponds to the site where later the stent crown of the endograft was implanted. The medial and distal measure points were arbitrarily chosen 2 cm distally and 4 cm distally of the proximal point, respectively (n=5). Values are mean±Standard Error of the Mean (SEM). (B) Aortic diameters measured in 2-cm interspaced native (unstented) porcine abdominal aortic segments under 100 mm Hg static pressure. The proximal measure point refers to the aortic segment proximally of the renal arteries. This also corresponds to the site where later the stent crown of the endograft was implanted. The medial and distal measure points were arbitrarily chosen 2 cm distally and 4 cm distally of the proximal point, respectively (n=5). (C) Cyclic circumferential strain measured after endograft implantation in…

Figure 3.. Endograft-induced stiffness gradient induces inflammatory and extracellular matrix-modulating genes in the aortic wall. (A) Representative images of aortic cross-sections of native vs stented aortas (interface segment) stained with hematoxylin and eosin (HE) and Elastica von Gieson (EvG; elastic lamellae are stained dark purple). Aortas were exposed to 6 hours of pulsatile pressurization. (B) Expression levels of Il6, Ccl2, Mmp2, and Mmp9 in the interface segment of stented aortas vs unstented aortas following 6 hours of static pressurization (n=5/group). Values are mean±SEM and expressed as fold changes relative to the mean expression level in unstented aortas (=1; dotted line). ns indicates non-significance. (C) Expression levels of Il6, Ccl2, Mmp2, and Mmp9 in the interface segment of stented aortas vs unstented aortas following 6 hours of pulsatile pressurization (n=5/group). Values are mean±SEM and expressed as fold changes relative to the mean expression level in unstented aortas (=1; dotted line). * indicates p<0.05 vs unstented. (D) Aortic expression levels of Il6, Ccl2, Mmp2, and Mmp9 at distinct axial locations along the endograft (as indicated) following 6 hours of…