[Influence of endoleaks on aneurysm volume and hemodynamics after endovascular aneurysm repair]

To evaluate the aneurysm volume and the intra-aneurysmatic pressure and maximal pressure pulse (dp/dtmax) in completely excluded aneurysms and cases with endoleaks.

In 36 mongrel dogs, experimental autologous aneurysms were treated with stent-grafts. All aortic side branches were ligated in 18 cases (group I) but were preserved in group II (n = 18). Aneurysm volumes were calculated from CT scans before and after intervention, and from follow-up CT scans at 1 week, 6 weeks and 6 months. Finally, for hemodynamic measurements, manometer-tipped catheters were introduced into the excluded aneurysm sac (group I and II), selectively in endoleaks (group II), and intraluminally for aortic reference measurement. Systemic hypertension was induced by volume load and pharmacologic stress. Pressure curves and dp/dt were simultaneously recorded and the ratios of aneurysm pressure to systemic reference pressure calculated.

At follow-up, type-II. endoleaks were excluded in all cases of group I by selective angiography. In contrast, endoleaks were evident in all cases of group II. Volumetric analysis of the aneurysms showed a benefit for group I with an improved aneurysm shrinkage: DeltaVolume + 0.08 %, - 1.62 % and -9.76 % at 1 week, 6 weeks and 6 months follow-up (median, group I), compared to + 1.43 %, + 0.67 %, and - 4.04 % (group II), p < 0.05. In case of complete aneurysm exclusion the ratio of systolic aneurysm pressure to systemic reference pressure was 0.662, 0.575 and 0.385 (median) at 1 week, 6 weeks and 6 months. The corresponding dp/dtmax ratios were 0.12, 0.07 and 0.04, respectively. However, within endoleaks selective measurements showed significantly increased pressure load: the ratios of systolic endoleak pressure to systemic reference pressure and the corresponding ratios for dp/dtmax were 0.882 and 0.913 (median), respectively. These hemodynamic findings were linear from hypotension, physiologic blood pressure to hypertension.

Occlusion of all aortic side branches of an aneurysm prior to stent-grafting reduces endoleaks and promotes aneurysm shrinkage. Complete aneurysm exclusion significantly reduces systolic pressure and dp/dt max. In contrast, endoleaks showed nearly systemic pressure load and undamped pulsatility.