Intimal Thrombus Research Articles

Feasibility and Safety of Remote Endovascular Catheter Navigation in a Porcine Model

To evaluate the feasibility and safety of a redesigned remotely operated vascular catheter versus manual catheter manipulation in a porcine model. Following femoral artery puncture and wire insertion, 4 pigs had either a robotically steered catheter (3 animals) or standard manual catheter manipulation to cannulate the contralateral iliac artery, bilateral renal arteries, and the superior mesenteric artery. After harvesting, the vessels were evaluated histologically by an independent laboratory using hematoxylin and eosin staining. Each cannulated artery was assessed for disruption of the intimal surface, intimal thrombus, damage to the tunica muscularis (dissection), mural hemorrhage, and inflammation by a pathologist who was blinded to the technique utilized for cannulation. No histological evidence of intimal thrombus, disruption, inflammation, or hemorrhage was demonstrated in any vessel section from the robotic cases. In the SMA, 1 of 61 sections from the robotic cases demonstrated mild focal dissection, while 1 of 9 slices from the manual control showed intimal thrombus. Of 129 slices from the renal arteries catheterized by the robotic system, 4 sections demonstrated mild focal dissection, while 2 of 23 sections from the manual control showed grade 1 intimal thrombus. In the iliofemoral arteries, 3 of 91 sections showed mild focal dissection in the robotic cases; in the manual control, 1 of 9 slices demonstrated extensive dissection and another showed mild intimal thrombus. The robotically operated catheter was at least as safe as manual manipulation. More extensive injury was actually observed with the manual technique. This newly designed robotic catheter has the potential to offer many advantages in terms of flexibility and range of motion.

Pathological changes in cerebral arteries following experimental subarachnoid hemorrhage: role of blood platelets.

The role of blood platelets in producing early intimal changes in cerebral arteries following subarachnoid hemorrhage (SAH) was examined by using 18 cats. Experimental SAH was produced by a rupture of the proximal portion of the right middle cerebral artery. Following SAH, the scanning electron microscope revealed that structural alterations in the intimal layer of major cerebral arteries occurred as early as 2 hours and became more severe by 48 hours. Vascular alterations, which were predominantly detected in the ruptured vessel, consisted of endothelial cell corrugation, detachment, crater formation, intimal adhesion of platelets and red blood cells, intimal thrombi, and reendothelialization. When cats were pretreated prior to SAH with an anti-platelet-aggregating agent, OKY-1581, the intimal blood elements and thrombi were clearly reduced, and reendothelialization was not observed. However, endothelial cell changes in the OKY-1581-treated group were very similar to those occurring in the nontreated group. While these results suggest that bioactive substances contained within blood platelets, such as growth factors, serotonin, and norepinephrine, have little effect on producing endothelial cell injury, platelets may be important in the initiation of reendothelialization following vessel injury.

Intraluminal thrombus and neointimal hyperplasia after microvascular surgery

Despite advances in instrumentation, suture materials, and techniques, thrombosis and intimal hyperplasia due to myointimal cell proliferation are still problems in microvascular anastomosis. Platelet factors stimulate smoothmuscle cell proliferation and migration, but little is known about platelet-vessel wall interaction in microvascular surgery. This study evaluates the effect of the disposition of platelet or luminal thrombus, or both, in intimal evolution in autologous venous micrografts interposed in the common carotid artery of 30 rats. Three hours postoperatively, venous graft and suture line endothelium was completely denuded, and the host artery exhibited focal de-endothelialization. Thrombus deposition was observed on suture line and venous graft luminal surfaces, whereas host artery-denuded areas exhibited platelet adhesion. Two weeks postoperatively, intimal thickenings developed in venous graft and suture line, becoming narrower toward the venous graft. The distribution and size of intimal thickening did not change significantly at later observation periods (3–8 months). Intimal thrombus deposition and intimal hyperplasia, appearing in later stages of evolution, show a similar pattern of distribution.

Accelerated "atherosclerosis". A morphologic study of 97 saphenous vein coronary artery bypass grafts.

Intimal thickening of uncertain cause has been noted in saphenous vein bypass grafts. To study the development of these changes, 97 vein grafts in 55 autopsied patients were examined by angiography and histology. Significant alterations in the grafts were confined to the intima and included thin layers of circumferential thrombus, concentric fibrous plaque and occlusive thrombus with organization. Circumferential nonocclusive intimal thrombus was present in 36 (73%) postoperative patent grafts. Concentric fibrous plaque, found in all twelve patent late grafts, showed changes characteristic of atheromata, including smooth muscle and foam cells. Intimal fibroelastosis was absent in the grafts, indicating that concentric plaque is not a simple response to increased pressure, or an "arterialization" of the vein. The findings suggest that early appearing concentric intimal thrombus is converted into fibrous plaque, and that this early thrombus is a factor in the development of acclereated "atherosclerosis" in saphenous vein bypass grafts.