Fluid displacement from intraluminal thrombus of abdominal aortic aneurysm as a result of uniform compression

Objectives The results after aneurysm repair with an endovascular aneurysm sealing (EVAS) system are dependent on the stability of the aneurysm sac and particularly the intraluminal abdominal aortic thrombus (ILT). The postprocedural ILT volume is decreased compared with preprocedural ILT volume in aortic aneurysm patients treated with EVAS. We hypothesize that ILT is not stable in all patients and pressurization of the ILT may result in displacement of fluids from the ILT, no differently than serum is displaced from whole blood when it settles. To date, the mechanism and quantification of fluid displacement from ILT are unknown. Methods The study included 21 patients who underwent elective open abdominal aortic aneurysm repair. The ILT was harvested as a routine procedure during the operation. After excision of a histologic sample of the ILT specimen in four patients, ILT volume was measured and the ILT was compressed in a dedicated compression setup designed to apply uniform compression of 200 mmHg for 5 min. After compression, the volumes of the remaining thrombus and the displaced fluid were measured. Results The median (interquartile-range) of ILT volume before compression was 60 (66) mL, and a median of 5.7 (8.4) mL of fluid was displaced from the ILT after compression, resulting in a median thrombus volume decrease of 11% (10%). Fluid components can be up to 31% of the entire ILT volume. Histologic examination of four ILT specimens showed a reduction of the medial layer of the ILT after compression, which was the result of compression of fluid-containing canaliculi. Conclusions Applying pressure of 200 mmHg to abdominal aortic aneurysm ILT resulted in the displacement of fluid, with a large variation among patients. Fluid displacement may result in decrease of ILT volume during and after EVAS, which might have implications on pre-EVAS volume planning and on stability of the endobags during follow-up which may lead to migration, endoleak or both.

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Visceral segment aortic thrombus is associated with proximal aortic degeneration after infrarenal abdominal aortic aneurysm repair

Vascular ◽

10.1177/17085381211021282 ◽

2021 ◽

pp. 170853812110212

Author(s):

Sean P Steenberge ◽

Daniel G Clair ◽

Matthew J Eagleton ◽

Francis J Caputo ◽

Christopher J Smolock ◽

...

Keyword(s):

Abdominal Aortic Aneurysm ◽

Aortic Aneurysm ◽

Endovascular Repair ◽

Abdominal Aortic Aneurysm Repair ◽

Infrarenal Abdominal Aortic Aneurysm ◽

Abdominal Aortic ◽

Aortic Thrombus ◽

Aneurysm Development ◽

Aneurysm Repair ◽

Aortic Aneurysm Repair

Objective To identify predictors of aortic aneurysm formation at or above an infrarenal abdominal aortic aneurysm repair. Methods A total of 881 infrarenal abdominal aortic aneurysm repairs were identified at a single institution from 2004 to 2008; 187 of the repairs were identified that had pre-operative and post-operative computed tomography imaging at least one year or greater to evaluate for aortic degeneration following repair. Aortic diameters at the celiac, superior mesenteric, and renal arteries were measured on all available computed tomographic scans. Aortic thrombus and calcification volumes in the visceral and infrarenal abdominal aortic segments were calculated. Multivariable modeling was used with log transformed variables to determine potential predictors of future aortic aneurysm development after infrarenal abdominal aortic aneurysm repair. Results Of the 187 patients in the cohort, 100 had an open abdominal aortic aneurysm repair while 87 were treated with endovascular repair. Proximal aortic aneurysms developed in 26% ( n = 49) of the cohort during an average of 72 ± 34.2 months of follow-up. After multivariable modeling, visceral segment aortic thrombus on pre-operative computed tomography imaging increased the risk of aortic aneurysm development above the infrarenal abdominal aortic aneurysm repair within both the open abdominal aortic aneurysm (hazard ratio 2.04, p = 0.033) and endovascular repair (hazard ratio 3.31, p = 0.004) cohorts. Endovascular repair was independently associated with a higher risk of future aortic aneurysm development after infrarenal abdominal aortic aneurysm repair when compared to open abdominal aortic aneurysm (hazard ratio 2.19, p = 0.025). Conclusions Visceral aortic thrombus present prior to abdominal aortic aneurysm repair and endovascular repair are both associated with an increased risk of future proximal aortic degeneration after infrarenal abdominal aortic aneurysm repair. These factors may predict patients at higher risk of developing proximal aortic aneurysms that may require complex aortic repairs.

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