Cardiovascular Engineering (dordrecht, Netherlands)最新文献_第10页

A computational approach to predict pulse transit time variations during postural change. 一种预测体位变化时脉冲传递时间变化的计算方法。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-09-01 DOI: 10.1007/s10558-007-9034-8

Jong Yong Abdiel Foo

{"title":"A computational approach to predict pulse transit time variations during postural change.","authors":"Jong Yong Abdiel Foo","doi":"10.1007/s10558-007-9034-8","DOIUrl":"https://doi.org/10.1007/s10558-007-9034-8","url":null,"abstract":"The human autonomic nervous system modulates blood pressure (BP) and heart rate in order to maintain homeostasis. Present techniques that monitor BP may cause discomforts to children. Pulse transit time change (DeltaPTT) is known to be inversely correlated to BP change. In this study, a mathematical model using only a few empirical parameters and the measured lower limb vascular path length is introduced to estimate DeltaPTT when a different posture is adopted. To assess the reliability of the model, 23 healthy children aged 8.4 +/- 2.3 years were recruited to adopt the sitting and supine position at discrete intervals. PTT measurements were obtained from their toe with respect to an ECG for both postures. The results showed that there was significant correlation between the model and measured DeltaPTT (P < 0.05; R(2) = 0.813). The findings herein suggest that this simple yet practical model can have the accuracy to estimate the DeltaPTT value. Moreover, it does not require the use of an ECG or pulse oximeter in its computation. Hence, it can provide a rapid prediction before a child adopts a postural change. This may be potentially useful for detection of children with vascular abnormalities at their lower limbs.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"7 3","pages":"121-6"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9034-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26873032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Cardiovascular simulation toolbox. 心血管模拟工具箱。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-06-01 DOI: 10.1007/s10558-007-9030-z

Liron Sheffer, William P Santamore, Ofer Barnea

引用次数: 12

Chest compression force of trained and untrained CPR rescuers. 受过训练和未受过训练的心肺复苏术施救者的胸部按压力。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-06-01 DOI: 10.1007/s10558-007-9029-5

Leslie A Geddes, Megan K Boland, Pervin R Taleyarkhan, Jillian Vitter

引用次数: 36

Left ventricular volume measurement by the conductance catheter and variations in the hematocrit in small animals. 小动物左心室容量测量与红细胞压积变化。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-06-01 DOI: 10.1007/s10558-007-9027-7

Werner Heimisch, Hubert Schad, Ralf Günzinger

{"title":"Left ventricular volume measurement by the conductance catheter and variations in the hematocrit in small animals.","authors":"Werner Heimisch, Hubert Schad, Ralf Günzinger","doi":"10.1007/s10558-007-9027-7","DOIUrl":"https://doi.org/10.1007/s10558-007-9027-7","url":null,"abstract":"Cardiac performance is quantitatively and continuously assessed from pressure-volume signals by using the conductance catheter technique even in small animals. Conductivity of blood, however, is dependent on hematocrit (Hct). Interdependence between hematocrit and volume measurement by the conductance catheter has been evaluated. In 12 male Wistar rats weighing 400-475 g, anesthetized and artificially ventilated, Hct was gradually lowered by isovolumic hemodilution ranging from 50% to 7%. Heparinized blood samples were drawn at decreasing Hct levels for centrifugation, for automated Hct measurement by a blood gas analyzer, and for conductance catheter volume measurements (CCV) in calibrated cuvettes. Substitution of about 2 ml colloid solution lowered the Hct initially from 47 +/- 2% to 36 +/- 3%; at the same time, CCV output rose by 36 +/- 14% for definite blood volume. There is a strong inverse linear relationship (absolute value of r > 0.96; P < 0.0001) between relative volume units (RVU) displayed by the volume acquisition device and the hematocrit for any calibrated blood cuvette. Slopes of the regression lines increase proportionally to the calibration volumes (28.3 microl: -0.25; 63.6 microl: -0.57; 113.1 microl: -0.92). These data document the direct interdependence between Hct and CCV. Consequently, careful Hct correction of the RVU recordings is necessary especially in small animals where even small amounts of substituted solutions result in a marked decrease in Hct and, thus, in pronounced blood volume misreadings.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"7 2","pages":"43-6"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9027-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26733610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

A one-dimensional model of blood flow in arteries with friction and convection based on the Womersley velocity profile. 基于沃默斯利速度剖面的动脉中有摩擦和对流的一维血流模型。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-06-01 DOI: 10.1007/s10558-007-9031-y

Karim Azer, Charles S Peskin

{"title":"A one-dimensional model of blood flow in arteries with friction and convection based on the Womersley velocity profile.","authors":"Karim Azer, Charles S Peskin","doi":"10.1007/s10558-007-9031-y","DOIUrl":"https://doi.org/10.1007/s10558-007-9031-y","url":null,"abstract":"In this paper, we present a one-dimensional model for blood flow in arteries, without assuming an a priori shape for the velocity profile across an artery (Azer, Ph.D. thesis, Courant Institute, New York University, 2006). We combine the one-dimensional equations for conservation of mass and momentum with the Womersley model for the velocity profile in an iterative way. The pressure gradient of the one-dimensional model drives the Womersley equations, and the velocity profiles calculated then feed back into both the friction and nonlinear parts of the one-dimensional model. Besides enabling us to evaluate the friction correctly and also to use the velocity profile to correct the nonlinear terms, having the velocity profile available as output should be useful in a variety of applications. We present flow simulations using both structured trees and pure resistance models for the small arteries, and compare the resulting flow and pressure waves under various friction models. Moreover, we show how to couple the one-dimensional equations with the Taylor diffusion limit (Azer, Int J Heat Mass Transfer 2005;48:2735-40; Taylor, Proc R Soc Lond Ser A 1953;219:186-203) of the convection-diffusion equations to drive the concentration of a solute along an artery in time.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"7 2","pages":"51-73"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9031-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26774069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 84

A noninvasive parametric evaluation of stress effects on global cardiovascular function. 应激对整体心血管功能影响的无创参数评价。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-06-01 DOI: 10.1007/s10558-007-9028-6

Richard Li-Chern Pan, John K-J Li

引用次数: 30

Gyro-effect stabilizes unstable permanent maglev centrifugal pump. 陀螺效应稳定不稳定永磁离心泵。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-03-01 DOI: 10.1007/s10558-007-9022-z

Kun-Xi Qian

{"title":"Gyro-effect stabilizes unstable permanent maglev centrifugal pump.","authors":"Kun-Xi Qian","doi":"10.1007/s10558-007-9022-z","DOIUrl":"https://doi.org/10.1007/s10558-007-9022-z","url":null,"abstract":"According to Earnshaw's Theorem (1839), the passive maglev cannot achieve stable equilibrium and thus an extra coil is needed to make the rotor electrically levitated in a heart pump. The author had developed a permanent maglev centrifugal pump utilizing only passive magnetic bearings, to keep the advantages but to avoid the disadvantages of the electric maglev pumps. The equilibrium stability was achieved by use of so-called \"gyro-effect\": a rotating body with certain high speed can maintain its rotation stably. This pump consisted of a rotor (driven magnets and an impeller), and a stator with motor coil and pump housing. Two passive magnetic bearings between rotor and stator were devised to counteract the attractive force between the motor coil iron core and the rotor driven magnets. Bench testing with saline demonstrated a levitated rotor under preconditions of higher than 3,250 rpm rotation and more than 1 l/min pumping flow. Rotor levitation was demonstrated by 4 Hall sensors on the stator, with evidence of reduced maximal eccentric distance from 0.15 mm to 0.07 mm. The maximal rotor vibration amplitude was 0.06 mm in a gap of 0.15 mm between rotor and stator. It concluded that Gyro-effect can help passive maglev bearings to achieve stabilization of permanent maglev pump; and that high flow rate indicates good hydraulic property of the pump, which helps also the stability of passive maglev pump.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"7 1","pages":"39-42"},"PeriodicalIF":0.0,"publicationDate":"2007-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9022-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26621116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Application of the method of characteristics for the study of shock waves in models of blood flow in the aorta. 特征方法在主动脉血流模型中冲击波研究中的应用。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-03-01 DOI: 10.1007/s10558-007-9024-x

R M Shoucri, M M Shoucri

引用次数: 9

Using a human cardiopulmonary model to study and predict normal and diseased ventricular mechanics, septal interaction, and atrio-ventricular blood flow patterns. 使用人体心肺模型来研究和预测正常和病变心室力学、间隔相互作用和房室血流模式。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-03-01 DOI: 10.1007/s10558-007-9025-9

C Luo, D L Ware, J B Zwischenberger, J W Clark

{"title":"Using a human cardiopulmonary model to study and predict normal and diseased ventricular mechanics, septal interaction, and atrio-ventricular blood flow patterns.","authors":"C Luo, D L Ware, J B Zwischenberger, J W Clark","doi":"10.1007/s10558-007-9025-9","DOIUrl":"https://doi.org/10.1007/s10558-007-9025-9","url":null,"abstract":"We upgraded our human cardiopulmonary (CP) model with additional data that enables it to more accurately simulate normal physiology. We then tested its ability to explain human disease by changing two parameter values that decrease ventricular compliance, and found that it could predict many of the hemodynamic, gas exchange, and autonomic abnormalities found in patients with left ventricular diastolic dysfunction (LVDD). The newly incorporated information includes high-fidelity pressure tracings simultaneously recorded from the RV and LV of a normal human in a cardiac catheterization laboratory, Doppler echocardiographic inlet flow velocity patterns, measures of right and left ventricular impedance, and atrial volumes. The revised cardiovascular section details the hemodynamics of a normal subject to the extent that it can now explain the effects of septal compliance on ventricular interaction, the differences in left and right ventricular pressure development, and venous blood gas mixing in the right atrium. The model can isolate the highly interrelated features of normal and abnormal physiology, and simultaneously demonstrate their interaction in a manner that would be very difficult or impossible using an intact organism. It may therefore help physicians and scientists understand, diagnose, and improve their treatment of complicated cardiovascular and pulmonary diseases. It could also simulate the hemodynamic and respiratory effects of ventricular and pulmonary assist devices, and thus help with their development.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"7 1","pages":"17-31"},"PeriodicalIF":0.0,"publicationDate":"2007-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9025-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26582504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Biothermal modeling of post-cryoplasty atherosclerosis in restenotic patients. 再狭窄患者冷冻成形术后动脉粥样硬化的生物热模拟。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2007-03-01 DOI: 10.1007/s10558-007-9026-8

H Men-Chi, T S Ravigururajan

引用次数: 7