Effects of Blood Flow on Radiofrequency Ablation of Tumors: Finite Elements and In Vitro Models

2003 ◽  
Author(s):  
Juan R. Cebral ◽  
Orlando Soto ◽  
Robert J. Lutz ◽  
Bradford J. Wood
Keyword(s):  
Blood Flow ◽  
Radiofrequency Ablation ◽  
Saline Solution ◽  
Numerical Models ◽  
In Vitro Models ◽  
Collective Effects ◽  
Ablation Lesion ◽  
Thermal Flow ◽  
Flow Process

The efficacy of radiofrequency ablation (RFA) treatments depends on the ability to ablate tumors completely while minimizing the damage to healthy tissue. Tissue cooling due to blood flow is an important factor affecting the size and shape of the ablation lesion. In this paper a new methodology for finite element modeling of the coupled electrical-thermal-flow process during RFA is presented. Our formulation treats heat losses due to blood flow explicitly rather than approximating the collective effects of blood vessles as a heat sink. Numerical models were compared to in vitro models using egg whites to simulate human tissue and a straight cylinder filled with a saline solution to simulate blood. Asymmetric burns were obtained close to the simulated blood vessels. Numerical results closely match the in vitro models.

In vitro quantification of radiofrequency ablation lesion size using intracardiac echocardiography in dogs

1996 ◽  
Vol 77 (2) ◽  
pp. 217-219 ◽  
Author(s):  
Jonathan M. Kalman ◽  
John Jue ◽  
Krishnankutty Sudhir ◽  
Peter Fitzgerald ◽  
Paul Yock ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Lesion Size ◽  
Intracardiac Echocardiography ◽  
Ablation Lesion

Abstract WP95: Parent Artery Curvature and Angle of Incidence of Blood Flow Affect Flow Diversion Effect of Pipeline

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Shinnosuke Obi ◽  
Chaitanya C Kulkarni ◽  
Raphael Segas ◽  
David Duong ◽  
Satoshi Tateshima
Keyword(s):  
Blood Flow ◽  
Circular Cross Section ◽  
Reynolds Numbers ◽  
In Vitro Models ◽  
Side Branch ◽  
Flow Diversion ◽  
Radius Of Curvature ◽  
Parent Artery ◽  
Angle Of Incidence

Introduction: Pipeline flow diversion stent is often placed in a tortuous anatomy. Nevertheless, effect of parent artery curvature on the flow diversion effect from Pipeline stent is poorly understood. The flow diversion effect could be enhanced or diminished depending on the curvature of Pipeline or the angle at which blood flow strikes the Pipeline (angle of incidence). These variations may explain why not all aneurysms are obliterated after Pipeline treatment despite its high efficacy. We evaluated the flow diversion effect of Pipeline in various parent artery curvatures and angle of incidence in in-vitro models. Methods: Four acrylic prototypes of curved tube with a side branch were constructed with circular cross section with the inner diameter of 3.8mm. The variation among the prototypes was made in terms of the radius of curvature R (R=25mm & 50mm), and the relative angle θ of the side branch (θ=60, 90, & 120). The angle θ of the side branch determines the angle of incidence. The identical Pipeline of diameter 4.75mm were placed to each prototype and the pressure loss (K) occurring in the flow through the Pipeline mesh was measured for the Reynolds numbers ranging from 100 to 800. Careful error analysis on the measured data made it possible to quantify weak change of the flow resistance due to the geometrical variations. Results: The parent artery curvature and angle of incidence of the blood flow clearly affect the flow diversion effect (K) of Pipeline (Fig.1). Flow diversion effect diminishes in tighter curvature. Also noted is higher angle of incidence reduces flow diversion effect. Conclusion: The parent artery curvature and angle of incidence are important parameters that may affect the efficacy of Pipeline.

Ischaemia and insulin, but not ischaemia and contraction, act synergistically in stimulating muscle glucose uptake in vivo in humans

2008 ◽  
Vol 116 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Marlies Bosselaar ◽  
Paul Smits ◽  
Cees J. Tack
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Contraction ◽  
Glucose Uptake ◽  
Muscle Blood Flow ◽  
In Vitro Models ◽  
Skeletal Muscle Glucose Uptake ◽  
The Impact

Ischaemia, like muscle contraction, has been reported to induce skeletal muscle glucose uptake in in vitro models. This stimulating effect appears independent of insulin and is probably mediated by activation of AMPK (AMP-activated protein kinase). In the present study, we hypothesized that in vivo in humans ischaemia- and insulin-induced glucose uptake are additive, and that the combined impact of ischaemia and contraction on glucose uptake is of a similar magnitude when each is applied separately. We assessed the effects of ischaemia with and without euglycaemic–hyperinsulinaemia (clamp; protocol 1) and with and without muscle contraction (protocol 2) on muscle FGU (forearm glucose uptake) in healthy subjects. Furthermore, we assessed the impact of ischaemia on FBF (forearm blood flow; plethysmography). In protocol 1, ischaemia increased FGU from 0.6±0.1 at baseline to 5.5±1.9 μmol·min−1·dl−1, and insulin increased FGU to 1.6±0.3 μmol·min−1·dl−1 (P<0.05 for both). The combination of ischaemia+insulin increased FGU to 15.5±2.2 μmol·min−1·dl−1 (P<0.05 compared with each stimulus alone). Maximal FBF obtained after ischaemia was similar with and without hyperinsulinaemia. In protocol 2, isometric contraction increased FGU from 0.3±0.1 to 2.7±0.8 μmol·min−1·dl−1 (P<0.05), but FGU was not significantly different from ischaemia compared with ischaemia+contraction. However, combined ischaemia+contraction resulted in a greater increase in FBF. In summary, ischaemia and insulin independently stimulate skeletal muscle glucose uptake in vivo in humans, whereas ischaemia and contraction do not. The observed differential effects of these stimuli on glucose uptake appear to be unrelated to changes in muscle blood flow.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Effect of caffeine on theophyliine on cerebral blood flow response to brain activation: In vitro and in vivo studies

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S198-S198
Author(s):  
Joseph R Meno ◽  
Thien-son K Nguyen ◽  
Elise M Jensen ◽  
G Alexander West ◽  
Leonid Groysman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Activation ◽  
In Vivo Studies ◽  
Blood Flow Response ◽  
Flow Response

The Mesothelial Cell as a Non-Thrombogenic Surface

1984 ◽  
Vol 52 (02) ◽  
pp. 102-104 ◽  
Author(s):  
L J Nicholson ◽  
J M F Clarke ◽  
R M Pittilo ◽  
S J Machin ◽  
N Woolf
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Blood Flow ◽  
Cell Surface ◽  
Mesothelial Cell ◽  
Mesothelial Cells ◽  
Plastic Film ◽  
In Vitro System ◽  
Scanning Electron

SummaryA technique for harvesting mesothelial cells is described. This entails collagenase digestion of omentum after which the cells can be cultured. The technique has been developed using the rat, but has also been successfully applied to human tissue. Cultured rat mesothelial cells obtained in this way have been examined by scanning electron microscopy. Rat mesothelial cells grown on plastic film have been exposed to blood in an in vitro system using a Baumgartner chamber and have been demonstrated to support blood flow. No adhering platelets were observed on the mesothelial cell surface. Fibroblasts similarily exposed to blood as a control were washed off the plastic.

Clinical Application of Radiofrequency Ablation for Malignant Liver Tumor during Interruption of Hepatic Blood Flow

2000 ◽  
Vol 18 ◽  
pp. 121-125
Author(s):  
Takashi Shibata ◽  
Takahiro Niinobu ◽  
Masashi Kitada ◽  
Takashi Shimano ◽  
Motohisa Takami ◽  
...  
Keyword(s):  
Blood Flow ◽  
Radiofrequency Ablation ◽  
Clinical Application ◽  
Hepatic Blood Flow ◽  
Liver Tumor ◽  
Malignant Liver Tumor ◽  
Malignant Liver
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