scholarly journals Virtual embolization for treatment support of intracranial AVMs using an interactive desktop and VR application

2021 ◽  
Author(s):  
Ulrike Sprengel ◽  
Patrick Saalfeld ◽  
Janneck Stahl ◽  
Sarah Mittenentzwei ◽  
Moritz Drittel ◽  
...  
Keyword(s):  
Blood Flow ◽  
Treatment Planning ◽  
Qualitative Evaluation ◽  
Quantitative Information ◽  
Patient Specific ◽  
Medical Expert ◽  
Complex Anatomy ◽  
Treatment Support ◽  
Capillary Bed ◽  
Altered Blood

Abstract Purpose The treatment of intracranial arteriovenous malformations (AVM) is challenging due to their complex anatomy. For this vessel pathology, arteries are directly linked to veins without a capillary bed in between. For endovascular treatment, embolization is carried out, where the arteries that supply the AVM are consecutively blocked. A virtual embolization could support the medical expert in treatment planning. Method We designed and implemented an immersive VR application that allows the visualization of the simulated blood flow by displaying millions of particles. Furthermore, the user can interactively block or unblock arteries that supply the AVM and analyze the altered blood flow based on pre-computed simulations. Results In a pilot study, the application was successfully adapted to three patient-specific cases. We performed a qualitative evaluation with two experienced neuroradiologist who regularly conduct AVM embolizations. The feature of virtually blocking or unblocking feeders was rated highly beneficial, and a desire for the inclusion of quantitative information was formulated. Conclusion The presented application allows for virtual embolization and interactive blood flow visualization in an immersive virtual reality environment. It could serve as useful addition for treatment planning and education in clinical practice, supporting the understanding of AVM topology as well as understanding the influence of the AVM’s feeding arteries.

Quantitation of neutrophil migration in acute bacterial pneumonia in rabbits

1994 ◽  
Vol 77 (6) ◽  
pp. 2593-2599 ◽  
Author(s):  
C. M. Doerschuk ◽  
J. Markos ◽  
H. O. Coxson ◽  
D. English ◽  
J. C. Hogg
Keyword(s):  
Blood Flow ◽  
Bacterial Pneumonia ◽  
Capillary Flow ◽  
Neutrophil Migration ◽  
Lower Lobe ◽  
Quantitative Information ◽  
Pulmonary Vessels ◽  
New Zealand White Rabbits ◽  
Air Space ◽  
Capillary Bed

The circulating neutrophils must slow down, adhere to the vessel walls, and migrate out of the microvasculature into the tissue and air spaces to defend the lung against microorganisms. The present study was designed to provide quantitative information about each of these steps. Streptococcus pneumoniae was instilled into the left lower lobe of New Zealand White rabbits to induce a pneumonia, and this lobe was compared with the same region of the opposite lung. The distribution of blood flow was determined by using radiolabeled macroaggregated albumin, and the patterns of perfusion within the capillary bed were quantitated using Monastral blue. The number of neutrophils delivered to the pneumonic site was determined by multiplying the circulating neutrophil count and blood flow. The results show that retention of 51Cr-labeled neutrophils was increased in the pneumonic region 2, 4, and 8 h after instillation of the organisms. The number of intracapillary neutrophils was increased in the pneumonic regions at all time points and in the control regions at 1 and 4 h. Neutrophil migration occurred in the pneumonic site, but only 1–2% of the total neutrophils delivered to the region migrated out of the pulmonary vessels into the air space. We conclude that the circulating neutrophils undergo a generalized response that increases their margination throughout the lung, that increased margination in the pneumonic site changes the distribution of capillary flow, and that the majority of neutrophils delivered to a pneumonic site are returned to the circulation without migrating into the air space.

Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries

2020 ◽  
Vol 22 (2) ◽  
pp. 619-636 ◽  
Author(s):  
Zbigniew Tyfa ◽  
Damian Obidowski ◽  
Krzysztof Jóźwik
Keyword(s):  
Blood Flow ◽  
Computer Aided Design ◽  
Volume Flow Rate ◽  
Flow Distribution ◽  
Primary Objective ◽  
Patient Specific ◽  
Blood Flow Distribution ◽  
Reconstruction Process ◽  
Outflow Cannula ◽  
The Brain

AbstractThe primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.

Blood-flow Restriction Training for a Person With Primary Progressive Multiple Sclerosis: A Case Report

2020 ◽  
Author(s):  
Evan T Cohen ◽  
Nicole Cleffi ◽  
Marianne Ingersoll ◽  
Herb I Karpatkin
Keyword(s):  
Multiple Sclerosis ◽  
Blood Flow ◽  
Case Report ◽  
Physical Therapist ◽  
Blood Flow Restriction ◽  
Patient Specific ◽  
Primary Progressive Multiple Sclerosis ◽  
Primary Progressive ◽  
Flow Restriction ◽  
Strength Tests

Abstract Objective Blood flow restriction (BFR) training, in which an inflatable cuff partially occludes blood flow around the proximal portion of a limb, coupled with low-intensity resistance training (LIRT) has resulted in gains comparable to traditional progressive resistive exercise in healthy populations. The use of BFR with LIRT may enable people with multiple sclerosis (MS) to improve strength without an increase in fatigue. The purpose of this case report is to describe the use of a BFR/LIRT program for a person with MS. Methods (Case Description) The patient was a 54-year-old woman with a 13-year history of primary progressive MS with an Extended Disability Severity Score of 3.0 out of 10. She received a BFR/LIRT program for both lower extremities (LE) biweekly for 12 weeks. Outcomes measured at baseline and at 6 and 12 weeks included the 12-item Multiple Sclerosis Walking Scale (MSWS-12), Fatigue Severity Scale (FSS), Patient-Specific Functional Scale (PSFS) (goals: running for exercise and pleasure for 45 minutes, 100% confidence in negotiating a flight of stairs, confidently and safely drive without restriction), and 14 LE strength tests. Results The intervention was well tolerated without adverse events. After 6 weeks, the MSWS-12 score improved; however, it did not exceed minimum detectable change (MDC). FSS was unchanged. All PSFS goals improved beyond MDC, and improvements in strength exceeded MDC in 2 out of 14 tests. After 12 weeks, MSWS-12 improvements persisted and the FSS score improved, but neither exceeded MDC. The PSFS improvements persisted. There were improvements exceeding MDC for 8 out of 14 strength tests. The remaining 6 strength tests improved but did not exceed MDC. Conclusion The patient had measurable improvements following the use of a BFR/LIRT program. BFR/LIRT may be an option for strength training in people with MS; however, research is needed to determine its safety and effectiveness across the population of people with MS. Impact Traditional physical therapist interventions for people with MS have been shown to be beneficial; however, their usefulness has been limited by fatigue. A growing body of literature has demonstrated the effects of a BFR/LIRT program on strength and other measures of physical function in healthy populations and those with chronic disease. This case report adds missing information to the existing literature and suggests directions for research on the effectiveness of BFR/LIRT in people with primary progressive MS.

Nitric oxide release in rat skeletal muscle capillary

1996 ◽  
Vol 270 (5) ◽  
pp. H1696-H1703 ◽  
Author(s):  
D. Mitchell ◽  
K. Tyml
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Leukocyte Adhesion ◽  
Microvascular Blood Flow ◽  
Capillary Length ◽  
Nitric Oxide Release ◽  
Longus Muscle ◽  
Potent Vasodilator ◽  
Capillary Bed ◽  
Synthase Inhibitor

Nitric oxide (NO) has been shown to be a potent vasodilator released from endothelial cells (EC) in large blood vessels, but NO release has not been examined in the capillary bed. Because the capillary bed represents the largest source of EC, it may be the largest source of vascular NO. In the present study, we used intravital microscopy to examine the effect of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on the microvasculature of the rat extensor digitorum longus muscle. L-NAME (30 mM) applied locally to a capillary (300 micron(s) from the feeding arteriole) reduced red blood cell (RBC) velocity [VRBC; control VRBC = 238 +/- 58 (SE) micron/s; delta VRBC = -76 +/- 8%] and RBC flux (4.4 +/- 0.7 to 2.8 +/- 0.7 RBC/s) significantly in the capillary, but did not change feeding arteriole diameter (Dcon = 6.3 +/- 0.7 micron, delta D = 5 +/- 7%) or draining venule diameter (Dcon = 10.1 +/- 0.6 micron, delta D = 4 +/- 2%). Because of the VRBC change, the flux reduction was equivalent to an increased local hemoconcentration from 1.8 to 5 RBCs per 100 micron capillary length. L-NAME also caused an increase in the number of adhering leukocytes in the venule from 0.29 to 1.43 cells/100 micron. L-NAME (30 mM) applied either to arterioles or to venules did not change capillary VRBC. Bradykinin (BK) locally applied to the capillary caused significant increases in VRBC (delta VRBC = 111 +/- 23%) and in arteriolar diameter (delta D = 40 +/- 5%). This BK response was blocked by capillary pretreatment with 30 mM L-NAME (delta VRBC = -4 +/- 27%; delta D = 5 +/- 9% after BK). We concluded that NO may be released from capillary EC both basally and in response to the vasodilator BK. We hypothesize that 1) low basal levels of NO affect capillary blood flow by modulating local hemoconcentration and leukocyte adhesion, and 2) higher levels of NO (stimulated by BK) may cause a remote vasodilation to increase microvascular blood flow.

scholarly journals Model Verification and Error Sensitivity of Turbulence-Related Tensor Characteristics in Pulsatile Blood Flow Simulations

Fluids ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 11
Author(s):  
Magnus Andersson ◽  
Matts Karlsson
Keyword(s):  
Blood Flow ◽  
Model Verification ◽  
Patient Specific ◽  
Flow Modeling ◽  
Spatiotemporal Resolution ◽  
Flow Simulations ◽  
Phase Averaging ◽  
Confidence Levels ◽  
Cardiovascular Flow ◽  
Computational Fluid Dynamics Cfd

Model verification, validation, and uncertainty quantification are essential procedures to estimate errors within cardiovascular flow modeling, where acceptable confidence levels are needed for clinical reliability. While more turbulent-like studies are frequently observed within the biofluid community, practical modeling guidelines are scarce. Verification procedures determine the agreement between the conceptual model and its numerical solution by comparing for example, discretization and phase-averaging-related errors of specific output parameters. This computational fluid dynamics (CFD) study presents a comprehensive and practical verification approach for pulsatile turbulent-like blood flow predictions by considering the amplitude and shape of the turbulence-related tensor field using anisotropic invariant mapping. These procedures were demonstrated by investigating the Reynolds stress tensor characteristics in a patient-specific aortic coarctation model, focusing on modeling-related errors associated with the spatiotemporal resolution and phase-averaging sampling size. Findings in this work suggest that attention should also be put on reducing phase-averaging related errors, as these could easily outweigh the errors associated with the spatiotemporal resolution when including too few cardiac cycles. Also, substantially more cycles are likely needed than typically reported for these flow regimes to sufficiently converge the phase-instant tensor characteristics. Here, higher degrees of active fluctuating directions, especially of lower amplitudes, appeared to be the most sensitive turbulence characteristics.

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