Observations on the Development of Mural Thrombi in Chronic Experimental Aneurysms in Sheep

Abstract

SummaryObservations were made on mural thrombi in experimental venous pouch aneurysms in sheep. Thrombi associated with mural tears and dissection consisted predominantly of laminated fibrin masking the earlier platelet deposition and infiltrating the wall to some extent. Thrombus growth was associated with platelet masses of Zahn and secondary fibrin deposition. Intervening spaces contained a variable quantity of coagulated plasma, fibrin mesh, leucocytes, disintegrating red cells and platelets rather than red thrombus as often suggested. Periodic deposition of platelet masses with surface rippling, the whorling patterns of laminated fibrin and mechanical disruption of red cells indicated the importance of haemodynamics. Coarse macroscopic lamination of mural thrombi was attributed in part to recurrent dissections between the wall and the mural thrombus and of the thrombus itself. These accounted for growth of thrombus with expansion of the wall and interference with organization of the thrombus. The model has proved suitable for the study of thrombogenesis and thrombus behaviour in aneurysms.

Implant Degradation and Poor Healing After Endovascular Repair of Abdominal Aortic Aneurysms: An Analysis of Explanted Stent-Grafts

“…Multilayering of dense fibrin and RBC areas into Zahn lines or circular spaces was recorded, corresponding to the successive layers of thrombus formed with time. 17 Two of the 3 autopsy cases (cases 8 and 2), harvested at 2.5 and 27 months, respectively, presented deficient healing similar to the findings in failed implants retrieved at surgery. These stent-grafts were encapsulated in unorganized thrombotic material.…”

Low pressure giant pulmonary artery aneurysm: a novel source of recurrent pulmonary embolism?

“…These studies concluded that aneurysm formation was due to a weakness of the vascular wall. Venous aneurysms and thrombus formation has been suggested in an experimental model (10). Several case reports suggest that progressive aneurysmal dilation of the pulmonary arteries can occur over a period of several years (9).…”

Experimental techniques and models in the study of the development and treatment of abdominal aortic aneurysm

“…None of the small animal aneurysm models reproduces the complex intraluminal thrombosis that is a prominent feature of almost all human AAAs, often occupying the bulk of the aneurysm sac. Its structure in the human disease is quite unusual (Figs 1 and 2) because, while the thrombus on the luminal aspect is a typical ®brin mesh with canaliculi and many in¯ammatory cells, the deeper juxtamural thrombus is often formed from many layers of organized thrombus characterized by few cells, a ®brinous extracellular matrix, lipid accumulation and occasional calci®cation 37,38 . Some degree of intraluminal thrombosis may be present in certain small animal models, but when this occurs it seems to consist only of ®brinous deposits on the damaged tunica intima 22 and not the complex organized thrombus characteristic of the human pathology.…”