Form and Size Matter: Increased Risk of Thrombosis in Microvessels with Surgically Created Endothelial Lesions

Abstract

Atherosclerosis is a known risk factor for flap loss in microsurgery. Several microsurgical techniques, like plaque removal, have been proposed for atherosclerotic vessels, but these techniques often induce intimal injuries. The aim of this study was to investigate the impact of various endothelial defects on the risk of thrombosis in a rat acute intimal injury model. Endothelial defects of various forms and sizes were created in the abdominal aorta of 30 male Wistar rats following a strict protocol. Defect sizes were measured and classified as round, horizontal, or vertical based on their configuration. An hour after reestablishing the blood flow, the abdominal aorta was harvested and the operation site was assessed for signs of thrombosis clinically and using light microscopy. Univariate and multiple linear regression analysis were performed to identify possible influencing factors on thrombosis. The mean defect size was 2.65 ± 1.19 mm. Intimal lesions were classified as round in 36.7%, horizontal in 33.3%, and vertical in 30% of specimens. Thrombus formation was detected in 46.7% clinically and in 50% histologically. Univariate regression analysis revealed that defect size ( = 0.048) and vertical form ( = 0.017) were significantly associated with thrombus formation. Multiple regression analysis corroborated vertical defects as a risk factor for thrombosis ( = 0.03). Endothelial injuries are associated with a high risk of thrombosis with highest risks associated with vertical defects. Arteries should be carefully examined for intimal defects before microvascular anastomosis, especially in the atherosclerotic patient.

Prediction of Flap Necrosis by Using Indocyanine Green Videoangiography in Cases of Venous Occlusion in the Epigastric Flap Model of the Rat

“…All procedures were performed under intravenous anesthesia (ketamine/xylazine) by using the femoral vein access on the right inguinal site after insertion of a microcatheter (Premicath; VYGON GmbH & Co. KG, Aachen, Germany) and application of one-eighth doses of 10% ketamine when needed, as previously described in detail. 18 19 …”

“… 7 23 The intraoperative ICG videoangiography of the epigastric flap was performed, as described in detail previously, by using weight-dependent intravenous injection of the ICG dye (ICG-PULSION; Pulsion Medical System AG, Munich, Germany). 19 24 The ICG videoangiography was conducted at fivefold magnification. The emission signal of the ICG dye was detected, color coded with respect to fluorescence intensity for a period of 120 seconds with 25 images per second, and recorded as arbitrary units (AU).…”

Perioperative anticoagulation in head and neck free flap reconstructions: Experience of an anticoagulative scheme and its modification

“…Microvascular anastomoses cause endothelial lesions, triggering extrinsic coagulation pathways. They also cause a change of rheology in the newly anastomosed vessels, fulfilling already at least two of the above-stated criteria (Mücke et al, 2017;Seo et al, 2015;Williams et al, 2004). Also, patients are initially fully, and in the course of hospital stay at least partially immobilized for several days, in addition to various other risk factors for thrombotic events favoring the indication for anticoagulation (Agnelli, 2004;Geerts et al, 2004).…”