Computational investigation of blood flow and flow-mediated transport in arterial thrombus neighborhood

Analysis of factors related to thrombosis in patients with PICC placements

This study aimed to investigate the conditions of patients with peripherally inserted central catheter (PICC) placements, analyze the risk factors influencing thrombosis in PICC-placed patients, and formulate more accurate and effective PICC management strategies. A total of 147 patients undergoing PICC placements were selected as the study subjects. Clinical data were collected, and the patients were divided into thrombosis and non-thrombosis groups. Detect levels of bilirubin, white blood cells, venous pressure, heparin concentration, blood flow, citric acid, and platelets. Pearson chi-square test, Spearman correlation analysis, as well as univariate and multivariate logistic regression were employed to analyze independent risk factors. Among the 147 patients with PICC placements, there were 84 males and 63 females. Thrombosis occurred in 116 cases, with an incidence rate of 78.91%. Pearson chi-square test showed a significant correlation between citric acid, blood flow, platelets and frailty (P < .001) with thrombosis formation. Spearman correlation analysis revealed a significant correlation between citric acid (ρ = -0.636, P < .001), blood flow (ρ = 0.584, P < .001), platelet count (ρ = 0.440, P < .001), frailty (ρ = -0.809, P < .001) and thrombosis in PICC placement patients. Univariate logistic regression analysis indicated a significant correlation between thrombosis formation and citric acid (OR = 0.022, 95% CI = 0.006-0.08, P < .001), blood flow (OR = 33.973, 95% CI = 9.538-121.005, P < .001), platelet count (OR = 22.065, 95% CI = 5.021-96.970, P < .001), frailty (OR = 0.003, 95% CI = 0.001-0.025, P < .001). Multivariate logistic regression analysis also showed a significant correlation between thrombosis formation and citric acid (OR = 0.013, 95% CI = 0.002-0.086, P < .001), blood flow (OR = 35.064, 95% CI = 6.385-192.561, P < .001), platelet count (OR = 4.667, 95% CI = 0.902-24.143, P < .001), frailty (OR = 0.006, 95% CI = 0.001-0.051, P < .001). However, gender (OR = 0.544, 95% CI = 0.113-2.612, P = .447), age (OR = 4.178, 95% CI = 0.859-20.317, P = .076), bilirubin (OR = 2.594, 95% CI = 0.586-11.482, P = .209), white blood cells (OR = 0.573, 95% CI = 0.108-3.029, P = .512), venous pressure (OR = 0.559, 95% CI = 0.129-2.429, P = .438), and heparin concentration (OR = 2.660, 95% CI = 0.333-21.264, P = .356) showed no significant correlation with thrombosis formation. Patients with PICC placements have a higher risk of thrombosis, citric acid, blood flow, platelet count and frailty are the main risk factors.

Investigating clot-flow interactions by integrating intravital imaging with in silico modeling for analysis of flow, transport, and hemodynamic forces

As a blood clot forms, grows, deforms, and embolizes following a vascular injury, local clot-flow interactions lead to a highly dynamic flow environment. The local flow influences transport of biochemical species relevant for clotting, and determines the forces on the clot that in turn lead to clot deformation and embolization. Despite this central role, quantitative characterization of this dynamic clot-flow interaction and flow environment in the clot neighborhood remains a major challenge. Here, we propose an approach that integrates dynamic intravital imaging with computer geometric modeling and computational flow and transport modeling to develop a unified in silico framework to quantify the dynamic clot-flow interactions. We outline the development of the methodology referred to as Intravital Integrated In Silico Modeling or IVISim, and then demonstrate the method on a sample set of simulations comprising clot formation following laser injury in two mouse cremaster arteriole injury model data: one wild-type mouse case, and one diYF knockout mouse case. Simulation predictions are verified against experimental observations of transport of caged fluorescent Albumin (cAlb) in both models. Through these simulations, we illustrate how the IVISim methodology can provide insights into hemostatic processes, the role of flow and clot-flow interactions, and enable further investigations comparing and contrasting different biological model scenarios and parameter variations.

Decoding thrombosis through code: a review of computational models

From the molecular level up to a blood vessel, thrombosis and hemostasis involves many interconnected biochemical and biophysical processes over a wide range of length and time scales. Computational modeling has gained eminence in offering insights into these processes beyond what can be obtained from in vitro or in vivo experiments, or clinical measurements. The multiscale and multiphysics nature of thrombosis has inspired a wide range of modeling approaches that aim to address how a thrombus forms and dismantles. Here, we review recent advances in computational modeling with a focus on platelet-based thrombosis. We attempt to summarize the diverse range of modeling efforts straddling the wide-spectrum of physical phenomena, length scales, and time scales; highlighting key advancements and insights from existing studies. Potential information gleaned from models is discussed, ranging from identification of thrombus-prone regions in patient-specific vasculature to modeling thrombus deformation and embolization in response to fluid forces. Furthermore, we highlight several limitations of current models, future directions in the field, and opportunities for clinical translation, to illustrate the state-of-the-art. There are a plethora of opportunity areas for which models can be expanded, ranging from topics of thromboinflammation to platelet production and clearance. Through successes demonstrated in existing studies described here, as well as continued advancements in computational methodologies and computer processing speeds and memory, in silico investigations in thrombosis are poised to bring about significant knowledge growth in the years to come.

svMorph: Interactive Geometry-Editing Tools for Virtual Patient-Specific Vascular Anatomies

We propose svMorph, a framework for interactive virtual sculpting of patient-specific vascular anatomic models. Our framework includes three tools for the creation of tortuosity, aneurysms, and stenoses in tubular vascular geometries. These shape edits are performed via geometric operations on the surface mesh and vessel centerline curves of the input model. The tortuosity tool also uses the physics-based Oriented Particles method, coupled with linear blend skinning, to achieve smooth, elastic-like deformations. Our tools can be applied separately or in combination to produce simulation-suitable morphed models. They are also compatible with popular vascular modeling software, such as simvascular. To illustrate our tools, we morph several image-based, patient-specific models to create a range of shape changes and simulate the resulting hemodynamics via three-dimensional, computational fluid dynamics. We also demonstrate the ability to quickly estimate the hemodynamic effects of the shape changes via the automated generation of associated zero-dimensional lumped-parameter models.

Microstructure aware modeling of biochemical transport in arterial blood clots

Flow-mediated transport of biochemical species is central to thrombotic phenomena. Comprehensive three-dimensional modeling of flow-mediated transport around realistic macroscale thrombi poses challenges owing to their arbitrary heterogeneous microstructure. Here, we develop a microstructure aware model for species transport within and around a macroscale thrombus by devising a custom preconditioned fictitious domain formulation for thrombus-hemodynamics interactions, and coupling it with a fictitious domain advection-diffusion formulation for transport. Microstructural heterogeneities are accounted through a hybrid discrete particle-continuum approach for the thrombus interior. We present systematic numerical investigations on unsteady arterial flow within and around a three-dimensional macroscale thrombus; demonstrate the formation of coherent flow structures around the thrombus which organize advective transport; illustrate the role of the permeation processes at the thrombus boundary and subsequent intra-thrombus transport; and characterize species transport from bulk flow to the thrombus boundary and vice versa.