Unravelling Surface Modification Strategies for Preventing Medical Device-Induced Thrombosis.

The use of biomaterials in implanted medical devices remains hampered by platelet adhesion and blood coagulation. Thrombus formation is a prevalent cause of failure of these blood-contacting devices. Although systemic anticoagulant can be used to support materials and devices with poor blood compatibility, its negative effects such as an increased chance of bleeding, make materials with superior hemocompatibility extremely attractive, especially for long-term applications. This review examines blood-surface interactions, the pathogenesis of clotting on blood-contacting medical devices, popular surface modification techniques, mechanisms of action of anticoagulant coatings, and discusses future directions in biomaterial research for preventing thrombosis. In addition, this paper comprehensively reviews several novel methods that either entirely prevent interaction between material surfaces and blood components or regulate the reaction of the coagulation cascade, thrombocytes, and leukocytes.

Angioscopic Evaluation of Atrial Septal Defect Closure Device Neo-Endothelialization.

Background Current guidelines recommend at least 6 months of antithrombotic therapy and antibiotic prophylaxis after septal-occluding device deployment in transcatheter closure of atrial septal defect. It has been estimated that it takes ≈6 months for complete neo-endothelialization; however, neo-endothelialization has not previously been assessed in vivo in humans. Methods and Results The neointimal coverage of septal occluder devices was evaluated 6 months after implantation in 15 patients by angioscopy from the right atrium. Each occluder surface was divided into 9 areas; the levels of endothelialization in each area were semiquantitatively assessed by 4-point grades. Device neo-endothelialization was sufficient in two thirds of patients, but insufficient in one third. In the comparison between patients with sufficiently endothelialized devices of average grade score ≥2 (good endothelialization group, n=10) and those with poorly endothelialized devices of average grade score <2 (poor endothelialization group, n=5), those in the poor endothelialization group had larger devices deployed (27.0 mm [25.0-31.5 mm] versus 17.0 mm [15.6-22.5 mm], respectively) and progressive right heart dilatation. The endothelialization was poorer around the central areas. Moreover, the prevalence of thrombus formation on the devices was higher in the poorly endothelialized areas than in the sufficiently endothelialized areas (Grade 0, 94.1%; Grade 1, 63.2%; Grade 2, 0%; Grade 3, 1.6%). Conclusions Neo-endothelialization on the closure devices varied 6 months after implantation. Notably, poor endothelialization and thrombus attachment were observed around the central areas and on the larger devices.

Incomplete neo-endothelialization of left atrial appendage closure devices is frequent after 6 months: a pilot imaging study.

PURPOSE: To bridge neo-endothelialization (NE) of implanted left atrial appendage closure (LAA/LAAC) devices, dual antiplatelet therapy is prescribed. Cardiac computed tomography angiography (cCTA) has been proposed for the evaluation of interventional LAAC. This prospective longitudinal observational study applied a standardized imaging protocol to detect progression of NE of LAAC devices 6 months after implantation. METHODS: Consecutive cCTA datasets of patients six months after LAAC were acquired and the standardized multi-planar reconstruction LAA occluder view for post-implantation evaluation (LOVE) algorithm was used. Residual flow of contrast agent inside the LAA without a peri-device leak (PDL) was defined as incomplete neo-endothelialization. Absence of residual flow was defined as complete neo-endothelialization. Since PDL allows residual flow in the LAA, irrespective of neoendothelialization, PDL were excluded from this study. Diabetes mellitus, liver disease, body-mass-index, age, device sizes and type will be assessed as predictors for incomplete NE. RESULTS: 53 consecutive patients were recruited for cCTA imaging. 36 (68%) showed no PDL and were included in the study (median age 77 years, 19% female). At median follow-up of 6 months (median 180 days, IQR 178-180), 44% of patients showed complete NE compared to 56% with NE still incomplete. Age, BMI, device type and size as well as prevalence of diabetes mellitus and liver disease did not show significant correlation with the completeness of NE. CONCLUSION: This pilot study showed that neo-endothelialization is still incomplete in a majority of patients at mid-term follow-up of 6 months after successful LAAC therapy. Further investigation on the consequences of incomplete endothelialization is needed to guide antiplatelet therapy schedules.

[Huge periprosthetic (peritransplant) seroma of a femoropopliteal bypass graft]. / Gigantskaia periproteznaia (periéksplantatnaia) seroma bedrenno podkolennogo shunta.

Presented herein is a clinical case report of a huge periprosthetic seroma of a femoropopliteal bypass graft made of polytetrafluoroethylene with a follow-up period and unsuccessful conservative management of more than one year. At 15 months after the primary operation, the bypass graft was retrieved and replaced by a knitted vascular graft made of polyester and impregnated with absorbable modified gelatine to decrease porosity, without relapse of the process of transudation into the periprosthetic space. Histological study of the retrieved conduit demonstrated the absence of formation of the intimal layer on the inner surface of the graft and fibrous capsule on the external surface of the main part of the length of the prosthesis, which, apparently, had provided a possibility of long-term preservation of porosity of the material.

--LAA Occluder View for post-implantation Evaluation (LOVE)--standardized imaging proposal evaluating implanted left atrial appendage occlusion devices by cardiac computed tomography.

BACKGROUND: A standardized imaging proposal evaluating implanted left atrial appendage (LAA) occlusion devices by cardiac computed tomography angiography (cCTA) has never been investigated. METHODS: cCTA datasets were acquired on a 3(rd) generation dual-source CT system and reconstructed with a slice thickness of 0.5 mm. An interdisciplinary evaluation was performed by two interventional cardiologists and one radiologist on a 3D multi-planar workstation. A standardized multi-planar reconstruction algorithm was developed in order to assess relevant clinical aspects of implanted LAA occlusion devices being outlined within a pictorial essay. RESULTS: The following clinical aspects of implanted LAA occlusion devices were evaluated within the most appropriate cCTA multi-planar reconstruction: (1) topography to neighboring structures, (2) peri-device leaks, (3) coverage of LAA lobes, (4) indirect signs of neo-endothelialization. These are illustrated within concise CT imaging examples emphasizing the potential value of the proposed cCTA imaging algorithm: Starting from anatomical cCTA planes and stepwise angulation planes perpendicular to the base of the LAA devices generates an optimal LAA Occluder View for post-implantation Evaluation (LOVE). Aligned true axial, sagittal and coronal LOVE planes offer a standardized and detailed evaluation of LAA occlusion devices after percutaneous implantation. CONCLUSIONS: This pictorial essay presents a standardized imaging proposal by cCTA using multi-planar reconstructions that enables systematical follow-up and comparison of patients after LAA occlusion device implantation.

Experimental Study of the Histologic Findings of the Neoendothelialization according to Diameter of Polytetrafluoroethylene in Dog / 대한정형외과연구학회지

The purpose of this study was to investigate the patency rates and the histologic findings of neoendothelialization according to the diameter of polytetrafluoroethylene (PTFE) which is the most widely used synthetic graft for blood vessel. Under the operating microscope, grafts of 3 and 5mm in diameter were implanted in both femoral arteries of ten mongrel dogs by interrupted end-to-end microanastomosis. They were divided into two groups according to the diameter of implanted PTFE (3 and 5mm). Each group had five dogs. The lengths of implanted PTFE were 20mm in both groups. All implanted grafts were 25 urn in fibril length and 0.39mm in wall thickness. Two grafts from one dog were harvested at 1, 2, 4, 8, and 12 weeks after implantation and all PTFE grafts were observed for patency rates. The histologic analysis was performed under a light microscope and scanning electron microscope. In conclusion, PTFE with larger diameter than that of recipient vessel is recommended as the grafts for implantation because PTFE is not as elastic as normal vessel.

Experimental Study of the Histologic Findings of the Neoendothelialization according to Length of Polytetrafluoroethylene in Rabbit / 대한정형외과연구학회지

The purpose of this study was to investigate the patency rates and the histologic findings of neoendothelialization according to the length of implanted polytetrafluoroethylene (PTFE) with an internal diameter of 3mm. Under the operating microscope, grafts of 8 and 24mm in length were implanted in the right carotid arteries of thirty rabbits by interrupted end-to-end microanastomosis. They were divided into two groups according to the length of implanted PTFE. Each group had fifteen rabbits. All implanted grafts were 25micro meter in fibril length and 0.39mm in wall thickness. Three grafts per group were harvested at 1, 2, 4, 8, and 12 weeks after implantation and all grafts were observed for patency rates and the histologic findings with a light microscope and scanning electron microscope. In conclusion, there was no difference in patency rates according to the length of implanted PTFE. However, the formation of neointima and subintimal tissue was delayed and incomplete in the longer implanted PTFE group.

The Histologic Study of the Neoendothelialization of Polytetrafluoroethylene as an Arterial Substitute in Rabbit / 대한정형외과학회잡지

The purpose of this study was to investigate the patency rates and the histologic findings of neoen- dothelialization according to the length of implanted polytetrafluoroethylene (PTFE) with an internal diameter of 3 mm. Under the operating microscope, grafts of 8 and 24 mm in length were implanted in the right carotid arteries of thirty rabbits by interrupted end-to-end microanastomosis. They were divided into two groups according to the length of implanted PTFE. Each group compised fifteen rabbits. All implanted grafts were 25 pm in fibril length and 0.39 mm in wall thickness. Three grafts per group were harvested at 1, 2, 4, 8, and 12 weeks after implantation respectively and all grafts were observed for patency rates and the histologic findings with light microscope and scanning electron microscope. In conclusion, there was no difference in patency rates according to the length of implanted PTFE and histologically the formation of neointima and subintimal tissue was delayed and incomplete in longer implanted PTFE.