Continuum modeling of thrombus formation and growth under different shear rates

Design and preparation of an artificial vascular scaffold with internal surface modification

BACKGROUND

Advances in regeneration methods have brought us improved vascular scaffolds with small diameters (φ < 6 mm) for enhancing biological suitability that solve their propensity for causing intimal hyperplasia post-transplantation.

METHODS

The correlation between the rehydration ratio of the hydrogel and its material concentration is obtained by adjusting the material ratio of the hydrogel solution. The vascular model with helical structure has been established and analyzed to verify the effect of helical microvascular structure on thrombosis formation by the fluid simulation methods. Then, the helical structure vascular has been fabricated by self-developed 3D bioprinter, the vascular scaffolds are freeze-dried and rehydrated in polyethylene glycol (PEG) solution.

RESULTS

The experimental results showed that the hybrid hydrogel had a qualified rehydration ratio when the content of gelatin, sodium alginate, and glycerol was 5, 6, and 3 wt%. The established flow channel model can effectively reduce thrombus deposition and improve long-term patency ratio. After PEG solution modification, the contact angle of the inner wall of the vascular scaffold was less than 30°, showing better hydrophilic characteristics.

CONCLUSION

In study, a small-diameter inner wall vascular scaffold with better long-term patency was successfully designed and prepared by wrinkling and PEG modification of the inner wall of the vascular scaffold. This study not only creates small-diameter vascular scaffolds with helical structure that improves the surface hydrophilicity to reduce the risk of thrombosis but also rekindles confidence in the regeneration of small caliber vascular structures.

Discrimination of the acute pulmonary embolism subtypes based on the novel MAPH score

Acute pulmonary embolism (APE) is a thromboembolism situation that can be central or peripheral. APE risk analysis and classification are essential for therapy planning. Our aim is to determine the novel MAPH score (including age, mean platelet volume (MPV), total protein, and hematocrit parameters) that can distinguish APE subtypes. Our retrospective cohort analysis includes 97 APE patients referred to the emergency medicine department who underwent pulmonary computed tomography angiography (CTA) in 24 h from 2020 to 2022. The hospital information system provided demographic, clinical, laboratory, and pulmonary CTA data. APE was classified into central (46 patients) and peripheral (51 patients) depending on the area of vascular involvement. The central APE group had higher hypertension (HT) (67.4%) and atrial fibrillation (AF) (39.1%) incidence than the peripheral APE group (all p values > 0.05). The central APE had higher total protein and platelet counts (p = 0.003 and p = 0.036), but peripheral APE had higher troponin values (p = 0.029). Central APE had 2.17 ± 0.85 MAPH and peripheral APE 1.76 ± 0.95 (p = 0.029). HT, AF, platelet count, and MAPH score differed significantly in univariate logistic regression (all p values < 0.05). However, only platelet count varied in multivariate logistic regression (p = 0.042). ROC curve analysis revealed that the MAPH score predicts central APE with 83% sensitivity and 45% specificity at a cut-off level of 1.5. The new MAPH score as an indicator of blood viscosity may distinguish between central and peripheral APE. Our result is significant, especially for centers with limited examinations, as it may accelerate the diagnosis and treatment processes. We think that our results might guide future investigations.

Topical Skin Application of Small-Molecule Antiplatelet Agent against Pressure Injury in Rat Models

Due to prolonged forced positioning, the incidence of intraoperative pressure injuries is high. This study aimed to explore the impact of small-molecule antiplatelet drugs on pressure injuries by locally applying them before an injury occurs. In the first part of this study, water-soluble tracers with different molecular weights were applied to normal and early-stage pressure-injured skin. Through digital cameras, spectrophotometers, and histological observations, the penetration of tracers into the epidermis was clarified. In the second part of this study, a water-soluble antiplatelet drug called Trapidil (molecular weight = 205 Da) was applied to the left side of the back of a rat before, during, and after compression, and the contralateral side served as a non-intervention control group. The differences in pressure injuries between the two groups were observed through a digital camera, an ultraviolet camera, and temperature measurement, and skin circulation and perfusion were assessed via an intravenous injection of Evans Blue. The first part of this study found that water-soluble tracers did not easily penetrate normal skin but could more easily penetrate pressure-damaged skin. The smaller the molecular weight of the tracer, the easier it penetrated the skin. Therefore, in the next step of research, water-soluble drugs with smaller molecular weights should be selected. The second part of this study found that, compared with the control group, the occurrence rates and areas of ulcers were lower, the gray value was higher, and the skin temperature was lower in the Trapidil group (p < 0.05). After the intravenous Evans Blue injection, skin circulation and perfusion in the Trapidil group were found to be better. In conclusion, this study found that the topical skin application of a small-molecule antiplatelet agent may have significant effects against pressure injuries by improving post-decompression ischemia, providing new insights into the prevention and treatment of intraoperative pressure injuries.

clotFoam: An open-source framework to simulate blood clot formation under arterial flow

Blood clotting involves the coupled processes of platelet aggregation and coagulation. Simulating clotting under flow in complex geometries is challenging due to multiple temporal and spatial scales and high computational cost. clotFoam is an open-source software developed in OpenFOAM that employs a continuum model of platelet advection, diffusion, and aggregation in a dynamic fluid environment and a simplified coagulation model with proteins that advect, diffuse, and react within the fluid and with wall-bound species through reactive boundary conditions. Our framework provides the foundation on which one can build more complex models and perform reliable simulations in almost any computational domain.

Imaging and biophysical modelling of thrombogenic mechanisms in atrial fibrillation and stroke

Atrial fibrillation (AF) underlies almost one third of all ischaemic strokes, with the left atrial appendage (LAA) identified as the primary thromboembolic source. Current stroke risk stratification approaches, such as the CHA₂DS₂-VASc score, rely mostly on clinical comorbidities, rather than thrombogenic mechanisms such as blood stasis, hypercoagulability and endothelial dysfunction-known as Virchow's triad. While detection of AF-related thrombi is possible using established cardiac imaging techniques, such as transoesophageal echocardiography, there is a growing need to reliably assess AF-patient thrombogenicity prior to thrombus formation. Over the past decade, cardiac imaging and image-based biophysical modelling have emerged as powerful tools for reproducing the mechanisms of thrombogenesis. Clinical imaging modalities such as cardiac computed tomography, magnetic resonance and echocardiographic techniques can measure blood flow velocities and identify LA fibrosis (an indicator of endothelial dysfunction), but imaging remains limited in its ability to assess blood coagulation dynamics. In-silico cardiac modelling tools-such as computational fluid dynamics for blood flow, reaction-diffusion-convection equations to mimic the coagulation cascade, and surrogate flow metrics associated with endothelial damage-have grown in prevalence and advanced mechanistic understanding of thrombogenesis. However, neither technique alone can fully elucidate thrombogenicity in AF. In future, combining cardiac imaging with in-silico modelling and integrating machine learning approaches for rapid results directly from imaging data will require development under a rigorous framework of verification and clinical validation, but may pave the way towards enhanced personalised stroke risk stratification in the growing population of AF patients. This Review will focus on the significant progress in these fields.

Computational Analysis of the Related Factors of Deep Vein Thrombosis (DVT) Formation in Patients Undergoing Hip Fracture Surgery

A retrospective study was conducted on 51 patients undergoing hip fracture surgery to investigate the factors associated with the formation of deep venous thrombosis (DVT). The independent sample t-test and correlation analysis were used to sort out and analyze the data. The findings are as follows. (1) Different gender samples showed significant differences in the Caprini score and thrombus location. Most DVTs in females are located in the posterior tibial vein and intermuscular veins. The Caprini score of females was significantly higher than that of males. (2) Age displays a positive correlation with DVT, coronary heart disease, hypertension, and different surgical types, respectively. (3) There is a correlation between age and operation duration. (4) Hyperlipidemia and cerebrovascular disease show a positive correlation with DVT. (5) There was a significant negative correlation between the Caprini score and the quantification of D-dimer. This indicates that in this sample, the higher the patients' Caprini score is, the lower the quantitation of D-dimer will be. (6) Hyperlipidemia and cardiac insufficiency show a positive correlation with cerebrovascular disease. Patients with hyperlipidemia and cardiac insufficiency may also suffer from cerebrovascular diseases.