scholarly journals A geometric scaling model for assessing the impact of aneurysm size ratio on hemodynamic characteristics

2014 ◽  
Vol 13 (1) ◽  
pp. 17 ◽  
Author(s):  
Yunling Long ◽  
Hongyu Yu ◽  
Zhizheng Zhuo ◽  
Ying Zhang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Size Ratio ◽  
Scaling Model ◽  
Aneurysm Size ◽  
Geometric Scaling ◽  
Hemodynamic Characteristics ◽  
The Impact

The influence of aneurysm morphology on the volume of hemorrhage after rupture

2021 ◽  
pp. 1-9
Author(s):  
Pablo M. Munarriz ◽  
Blanca Navarro-Main ◽  
Jose F. Alén ◽  
Luis Jiménez-Roldán ◽  
Ana M. Castaño-Leon ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Univariate Analysis ◽  
Size Ratio ◽  
Computer Assisted ◽  
Data Set ◽  
Aneurysm Size ◽  
Risk Of Rupture ◽  
Morphological Variables ◽  
Hemorrhage Volume ◽  
The Impact

OBJECTIVE Factors determining the risk of rupture of intracranial aneurysms have been extensively studied; however, little attention is paid to variables influencing the volume of bleeding after rupture. In this study the authors aimed to evaluate the impact of aneurysm morphological variables on the amount of hemorrhage. METHODS This was a retrospective cohort analysis of a prospectively collected data set of 116 patients presenting at a single center with subarachnoid hemorrhage due to aneurysmal rupture. A volumetric assessment of the total hemorrhage volume was performed from the initial noncontrast CT. Aneurysms were segmented and reproduced from the initial CT angiography study, and morphology indexes were calculated with a computer-assisted approach. Clinical and demographic characteristics of the patients were included in the study. Factors influencing the volume of hemorrhage were explored with univariate correlations, multiple linear regression analysis, and graphical probabilistic modeling. RESULTS The univariate analysis demonstrated that several of the morphological variables but only the patient’s age from the clinical-demographic variables correlated (p < 0.05) with the volume of bleeding. Nine morphological variables correlated positively (absolute height, perpendicular height, maximum width, sac surface area, sac volume, size ratio, bottleneck factor, neck-to-vessel ratio, and width-to-vessel ratio) and two correlated negatively (parent vessel average diameter and the aneurysm angle). After multivariate analysis, only the aneurysm size ratio (p < 0.001) and the patient’s age (p = 0.023) remained statistically significant. The graphical probabilistic model confirmed the size ratio and the patient’s age as the variables most related to the total hemorrhage volume. CONCLUSIONS A greater aneurysm size ratio and an older patient age are likely to entail a greater volume of bleeding after subarachnoid hemorrhage.

The Impact of the Body Mass Index on Outcome After Subarachnoid Hemorrhage

Neurosurgery ◽  
2013 ◽  
Vol 73 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Johannes Platz ◽  
Erdem Güresir ◽  
Patrick Schuss ◽  
Jürgen Konczalla ◽  
Volker Seifert ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Subarachnoid Hemorrhage ◽  
Body Mass ◽  
Glasgow Outcome Scale ◽  
The Body ◽  
Favorable Outcome ◽  
World Federation ◽  
Obese Patients ◽  
Aneurysm Size ◽  
The Impact

Abstract BACKGROUND: Obesity is a risk factor for cardiovascular disease and associated with a poor outcome, especially for intensive care patients. However, recent studies have described favorable outcomes of obese patients after stroke, a phenomenon called the “obesity paradox.” OBJECTIVE: To assess the impact of the body mass index (BMI) on outcome after subarachnoid hemorrhage (SAH). METHODS: We analyzed the data for 741 SAH patients. A BMI greater than 25 kg/m2 was considered overweight and greater than 30 kg/m2 obese. The outcome according to the Glasgow Outcome Scale at discharge and after 6 months was assessed using logistic regression analysis. RESULTS: According to the BMI, 268 patients (36.2%) were overweight and 113 (15.2%) were obese. A favorable outcome (Glasgow Outcome Scale score &gt;3) was achieved in 53.0% of overweight patients. In contrast, 61.4% of the 360 patients with a normal BMI had a favorable outcome (P = .021). However, in the multivariate analysis, only age (odds ratio [OR]: 1.051, 95% confidence interval [CI]: 1.04-1.07, P &lt; .001), World Federation of Neurological Surgeons grade (OR: 2.095, 95% CI: 1.87-2.35, P &lt; .001), occurrence of vasospasm (OR: 2.90, 95% CI: 1.94-4.34, P &lt; .001), and aneurysm size larger than 12 mm (OR: 2.215, 95% CI: 1.20-4.10, P = .011) were independent predictors of outcome after 6 months. Of the 321 poor grade patients (World Federation of Neurological Surgeons score &gt;3), 171 (53.3%) were overweight. Of these, 21.6% attained a favorable outcome compared with 35.3% of normal-weight patients (P = .006). CONCLUSION: Although many physicians anticipate a worse outcome for obese patients, in our study, the BMI was not an independent predictor of outcome. Based on the BMI, obesity seems to be negligible for outcome after SAH compared with the impact of SAH itself, the patient's age, occurrence of vasospasm, or aneurysm size.

The Role of Reynolds Number Effect and Tip Leakage in Compressor Geometry Scaling at Low Turbulent Reynolds Numbers

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Markus Diehl ◽  
Christoph Schreiber ◽  
Jürg Schiffmann
Keyword(s):  
Reynolds Number ◽  
Surface Friction ◽  
Reynolds Numbers ◽  
Small Scale ◽  
Tip Leakage ◽  
Reynolds Number Effect ◽  
Geometric Scaling ◽  
Compressor Performance ◽  
The Impact

Abstract In compressor design, a convenient way to save time is to scale an existing geometry to required specifications, rather than developing a new design. The approach works well when scaling compressors of similar size at high Reynolds numbers but becomes more complex when applied to small-scale machines. Besides the well-understood increase in surface friction due to increased relative surface roughness, two other main problems specific to small-scale turbomachinery can be specified: (1) the Reynolds number effect, describing the non-linear dependency of surface friction on Reynolds number and (2) increased relative tip clearance resulting from manufacturing limitations. This paper investigates the role of both effects in a geometric scaling process, as used by a designer. The work is based on numerical models derived from an experimentally validated geometry. First, the effects of geometric scaling on compressor performance are assessed analytically. Second, prediction capabilities of reduced-order models from the public domain are assessed. In addition to design point assessment, often found in other publications, the models are tested at off-design. Third, the impact of tip leakage on compressor performance and its Reynolds number dependency is assessed. Here, geometries of different scale and with different tip clearances are investigated numerically. Fourth, a detailed investigation regarding tip leakage driving mechanisms is carried out and design recommendations to improve small-scale compressor performance are provided.

2D and 3D Morphologic Metrics Associated Intracranial Aneurysm Rupture

2010 ◽  
Author(s):  
Ding Ma ◽  
Sabareesh K. Natarajan ◽  
Jianping Xiang ◽  
Adnan Siddiqui ◽  
Elad I. Levy ◽  
...  
Keyword(s):  
Image Segmentation ◽  
Intracranial Aneurysms ◽  
Vessel Diameter ◽  
Aneurysm Rupture ◽  
Size Ratio ◽  
Patient Specific ◽  
3D Image ◽  
Parent Vessel ◽  
3D Image Segmentation ◽  
Aneurysm Size

Intracranial aneurysms (IAs) rupture results in severe morbidity and mortality. Therefore indentifying IA rupture risk is highly critical. Although it has been recognized that IA rupture is the result of a complex vascular degeneration process involving multiple mechanobiological factors, such information for each patient is not readily available in clinical setting. Alternatively, morphology and hemodynamic metrics can be derived from routine patient-specific imaging. In previous studies, a number of morphological metrics derived from analysis of reconstructed vascular 3D geometry have shown significance in discriminating ruptured from unruptued IAs, including in particular aneurysm size ratio, defined as IA size divided by the parent vessel diameter. However, these measures rely on 3D image segmentation and measurement, which makes them less practical in current angiographic rooms often equipped with only biplane angiogram capability and even when 3D rotational angiography is available, on-site 3D image segmentation and analyses are still not practical. Our foregoing study examined three parameters measured on 2D angiographs: aneurysm Size Ratio (SR), Aspect Ratio (AR) and Size. We found that SR had the strongest correlation with IA rupture. The current study further evaluates these geometric metrics, measured both from 3D and 2D images, with a larger cohort of saccular intracranial aneurysms.

Biotelemetry transmitter implantation in rodents: impact on growth and circadian rhythms

2004 ◽  
Vol 286 (5) ◽  
pp. R967-R974 ◽  
Author(s):  
Lisa R. Leon ◽  
Larry D. Walker ◽  
David A. DuBose ◽  
Lou A. Stephenson
Keyword(s):  
Body Weight ◽  
Core Body Temperature ◽  
Circadian Rhythmicity ◽  
Size Ratio ◽  
The Other ◽  
Experimental Paradigm ◽  
Surgical Implantation ◽  
Core Body ◽  
The Impact ◽  
Mouse Body Weight

The implantation of a biotelemetry transmitter for core body temperature (Tc) and motor activity (MA) measurements is hypothesized to have effects on growth and circadian rhythmicity depending on animal body-to-transmitter (B:T) size ratio. This study examined the impact of transmitter implantation (TM) on body weight, food intake (FI), water intake (WI), and circadian Tc and MA rhythms in mice (23.8 ± 0.04 g) and rats (311.5 ± 5.1 g) receiving no treatment (NT), anesthesia, laparotomy (LAP), and TM. The B:T size ratio was 6:1 and 84:1 for mice and rats, respectively. In mice, body weight required 14 days to recover to presurgical levels and never attained the level of the other groups. FI recovered in 3 days, whereas WI never reached presurgical levels. Rat body weight did not decrease below presurgical levels. FI and WI recovered to presurgical levels in rats by day 2 postsurgery. Anesthesia decreased mouse body weight for 1 wk, but was without effect in rats. LAP significantly decreased body weight for 5 days in mice and 1 day in rats, showing a significant effect of the surgical procedure in the absence of TM in both species. Circadian Tc and MA rhythms were evident within the first week in both species, indicating dissociation between circadian rhythmicity and recovery of growth variables. Cosinor analysis showed a TM effect on Tc min, Tc max, mesor, amplitude, and period of mice, whereas only the amplitude of the rhythm was affected in rats. These data indicate that a large B:T size ratio is associated with minimization of the adverse effects of surgical implantation. We recommend that B:T size ratio, recovery of presurgical body weight, and display of a robust circadian Tc and MA rhythm be established before collection of biotelemetry data collection under an experimental paradigm.

Bayes geometric scaling model for common cause failure rates

2010 ◽  
Vol 95 (2) ◽  
pp. 70-76 ◽  
Author(s):  
Athena Zitrou ◽  
Tim Bedford ◽  
Lesley Walls
Keyword(s):  
Failure Rates ◽  
Common Cause ◽  
Common Cause Failure ◽  
Scaling Model ◽  
Geometric Scaling

Larger size ratio associated with the rupture of very small (≤3 mm) anterior communicating artery aneurysms

2016 ◽  
Vol 9 (3) ◽  
pp. 278-282 ◽  
Author(s):  
Ting Xu ◽  
Boli Lin ◽  
Shuailiang Liu ◽  
Xiaotong Shao ◽  
Nengzhi Xia ◽  
...  
Keyword(s):  
Multivariate Regression ◽  
Univariate Analysis ◽  
Maximum Size ◽  
Aneurysm Rupture ◽  
Size Ratio ◽  
Anterior Communicating Artery ◽  
Rupture Risk ◽  
Aneurysm Size ◽  
Aneurysm Morphology ◽  
Small Aneurysms

BackgroundAnterior communicating artery (AcoA) aneurysms have a high rupture risk, and ruptured AcoA aneurysms tend to be smaller than other intracranial aneurysms. We aimed to determine the incidence and morphologic predictors of aneurysm rupture of very small AcoA aneurysms.MethodsWe conducted a retrospective analysis of 519 consecutive patients with single AcoA aneurysms between December 2007 and February 2015 in our hospital. Aneurysm morphologies were re-measured using CT angiography images. Very small aneurysms were defined as those with a maximum size ≤3 mm, and small aneurysms were defined as those with a maximum size ≤5 mm. Multivariate regression analyses were used to determine the association between aneurysm morphology and aneurysm rupture status.ResultsOf the 474 ruptured AcoA aneurysms, 134 (28.3%) aneurysms were very small and 278 (58.6%) aneurysms were small. In the univariate analysis for very small aneurysms, larger aneurysm size (p=0.037), larger size ratio (p=0.002), higher aneurysm height (p=0.038), smaller vessel size (p=0.012), and dominant A1 segment configuration (p=0.011) were associated with aneurysm rupture. Multivariate analysis revealed that a larger size ratio was independently associated with the rupture status of the very small aneurysms (OR 3.69, 95% CI 1.5 to 9.0; p=0.004), and larger aneurysm size, larger size ratio, and dominant A1 segment configuration were associated with the rupture of small aneurysms.ConclusionsAbout one-third of ruptured AcoA aneurysms were very small. A larger size ratio, rather than other aneurysm morphologies, was independently associated with the rupture of very small AcoA aneurysms.

scholarly journals The Impact of Inflow Angle on Aneurysm Hemodynamics: A Simulation Study Based on Patient-Specific Intracranial Aneurysm Models

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiao Mo ◽  
Qianqian Meng ◽  
Xinjian Yang ◽  
Haiyun Li
Keyword(s):  
Flow Velocity ◽  
Image Data ◽  
Patient Specific ◽  
Rupture Risk ◽  
Hemodynamic Changes ◽  
Structure Interaction ◽  
Velocity Flow ◽  
Hemodynamic Characteristics ◽  
The Impact ◽  
Fully Coupled

The inflow angle of intracranial aneurysms (IAs) can impact the hemodynamics of IAs, therefore it is likely to contribute to IA clinical rupture risk stratification. This study aimed to assess the effect of inflow angle on the hemodynamics of IAs, as well as its potential ability to predict IA rupture risk. A novel algorithm was developed to build a series of inflow angle models on patient-specific IA models, which were reconstructed from IA 3DRA image data of eleven clinical patients. Fully coupled fluid-structure interaction (FSI) simulations were performed to quantify hemodynamic characteristics of the established IA models with various inflow angles. Hemodynamic parameters including wall shear stress (WSS), flow velocity, flow pattern, inflow zone, impingement region, pressure, and energy loss (EL) were calculated and analyzed. It was demonstrated from the analysis that a rise in the IA inflow angle is associated with the following hemodynamic changes: more direct blood flowed into the aneurysm sac, higher velocity at the upside of the aneurysm, upregulated flow velocity and WSS in the aneurysm, more complicated flow patterns, extended inflow zone, the impingement region moving upward from the neck to the apex of the aneurysm, and higher WSS and larger flow velocity at the inflow zone of the IAs. Therefore, the proposed method may be helpful in exploring the hemodynamic variations of IAs with inflow angles. The findings could be conducive to hemodynamic studies on the association between IA inflow angle and its rupture risk.

scholarly journals A thermodynamic scaling law for electrically perturbed lipid membranes: validation with the steepest-entropy-ascent framework

2020 ◽  
Author(s):  
I. Goswami ◽  
R. Bielitz ◽  
S.S. Verbridge ◽  
M.R. von Spakovsky
Keyword(s):  
Electric Fields ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Scaling Law ◽  
Cancer Therapeutics ◽  
Successful Implementation ◽  
Outer Cell ◽  
Scaling Model ◽  
The Impact

AbstractExperimental evidence has demonstrated the potential of transient pulses of electric fields to alter mammalian cell phenotypes. Strategies with these pulsed electric fields (PEFs) have been developed for clinical applications in cancer therapeutics, in-vivo decellularization, and tissue regeneration. Successful implementation of these strategies involves understanding how PEFs impact the cellular structures and, hence, cell behavior. The caveat, however, is that the PEF parameter space comprised of different pulse widths, amplitudes, and the number of pulses is very large, and design of experiments to explore all possible combinations of PEF parameters is prohibitive from a cost and time standpoint. In this study, a scaling law based on the Ising model is introduced to understand the impact of PEFs on the outer cell lipid membrane so that an understanding developed in one PEF pulse regime may be extended to another. Experimental study is used to argue for the scaling model. Next, the validity of this scaling model to predict the behavior of both thermally quenched and electrically perturbed lipid membranes is demonstrated via computational predictions made by the steepest-entropy-ascent quantum thermodynamic (SEAQT) framework. Based on the simulation results, a form of scaled PEF parameters is thus proposed for lipid membrane.

The Impact of Integrated Evaluation of Hemodynamics on Management of Preterm Infants with Late-Onset Compromised Systemic Circulation

2017 ◽  
Vol 34 (10) ◽  
pp. 1011-1019 ◽  
Author(s):  
Reem Amer ◽  
Reem Kalash ◽  
Mary Seshia ◽  
Yasser Elsayed
Keyword(s):  
Cohort Study ◽  
Retrospective Cohort ◽  
Primary Outcome ◽  
Near Infrared ◽  
Tissue Oxygenation ◽  
Late Onset ◽  
Systemic Circulation ◽  
Hemodynamic Characteristics ◽  
The Impact ◽  
Neonatal Echocardiography

Objectives To study the impact of integrated evaluation of hemodynamics (IEH), using targeted neonatal echocardiography (TNE), cerebral regional tissue oxygenation (crRTO), and fractional oxygen extraction (FOE), using near-infrared spectroscopy (NIRS) on the management of infants with late-onset compromised systemic circulation (LCSC), and evaluation of the hemodynamic characteristics. Study Design Retrospective cohort study comparing infants with LCSC who underwent IEH (April 2014 to May 2016) with an earlier EPOCH who did not undergo IEH (January 2012 to March 2014). The primary outcome was the time to recovery. Results Total 43 infants were included; 18 infants underwent IEH with a median (IQR) 2 (1–3) assessments per infant. The time to recovery was shorter in IEH group with a median (IQR) 28 hours (15–62) compared with non-IEH group 96 hours (30–160). Autoregulation was compromised in 50%, and systemic vascular resistance (SVR) was low in 67%. Conclusion IEH was associated with shorter time to recovery in infants with LCSC.

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