Cardiovascular Engineering (dordrecht, Netherlands)最新文献_第8页

Multiscale analysis of heart rate dynamics: entropy and time irreversibility measures. 心率动力学的多尺度分析:熵和时间不可逆性测量。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-06-01 DOI: 10.1007/s10558-007-9049-1

Madalena D Costa, Chung-Kang Peng, Ary L Goldberger

引用次数: 285

Modeling heart rate regulation--part I: sit-to-stand versus head-up tilt. 心率调节模型——第一部分：坐立对抗平头倾斜。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-06-01 DOI: 10.1007/s10558-007-9050-8

Mette S Olufsen, April V Alston, Hien T Tran, Johnny T Ottesen, Vera Novak

{"title":"Modeling heart rate regulation--part I: sit-to-stand versus head-up tilt.","authors":"Mette S Olufsen, April V Alston, Hien T Tran, Johnny T Ottesen, Vera Novak","doi":"10.1007/s10558-007-9050-8","DOIUrl":"10.1007/s10558-007-9050-8","url":null,"abstract":"In this study we describe a model predicting heart rate regulation during postural change from sitting to standing and during head-up tilt in five healthy elderly adults. The model uses blood pressure as an input to predict baroreflex firing-rate, which in turn is used to predict efferent parasympathetic and sympathetic outflows. The model also includes the combined effects of vestibular and central command stimulation of muscle sympathetic nerve activity, which is increased at the onset of postural change. Concentrations of acetylcholine and noradrenaline, predicted as functions of sympathetic and parasympathetic outflow, are then used to estimate the heart rate response. Dynamics of the heart rate and the baroreflex firing rate are modeled using a system of coupled ordinary delay differential equations with 17 parameters. We have derived sensitivity equations and ranked sensitivities of all parameters with respect to all state variables in our model. Using this model we show that during head-up tilt, the baseline firing-rate is larger than during sit-to-stand and that the combined effect of vestibular and central command stimulation of muscle sympathetic nerve activity is less pronounced during head-up tilt than during sit-to-stand.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":" ","pages":"73-87"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2767463/pdf/nihms-47525.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41060370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Statistical considerations and techniques for understanding physiological data, modeling, and treatments. 理解生理数据、建模和治疗的统计学考虑和技术。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-06-01 DOI: 10.1007/s10558-007-9052-6

Ben G Fitzpatrick

引用次数: 1

Modeling heart rate regulation--part II: parameter identification and analysis. 心率调节建模——第二部分:参数辨识与分析。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-06-01 DOI: 10.1007/s10558-007-9048-2

K R Fowler, G A Gray, M S Olufsen

{"title":"Modeling heart rate regulation--part II: parameter identification and analysis.","authors":"K R Fowler, G A Gray, M S Olufsen","doi":"10.1007/s10558-007-9048-2","DOIUrl":"https://doi.org/10.1007/s10558-007-9048-2","url":null,"abstract":"In part I of this study we introduced a 17-parameter model that can predict heart rate regulation during postural change from sitting to standing. In this subsequent study, we focus on the 17 model parameters needed to adequately represent the observed heart rate response. In part I and in previous work (Olufsen et al. 2006), we estimated the 17 model parameters by minimizing the least squares error between computed and measured values of the heart rate using the Nelder-Mead method (a simplex algorithm). In this study, we compare the Nelder-Mead optimization method to two sampling methods: the implicit filtering method and a genetic algorithm. We show that these off-the-shelf optimization methods can work in conjunction with the heart rate model and provide reasonable parameter estimates with little algorithm tuning. In addition, we make use of the thousands of points sampled by the optimizers in the course of the minimization to perform an overall analysis of the model itself. Our findings show that the resulting least-squares problem has multiple local minima and that the non-linear-least squares error can vary over two orders of magnitude due to the complex interaction between the model parameters, even when provided with reasonable bound constraints.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"8 2","pages":"109-19"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9048-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"27203025","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: 11

Sensitivity analysis and model assessment: mathematical models for arterial blood flow and blood pressure. 敏感性分析和模型评估:动脉血流和血压的数学模型。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-06-01 DOI: 10.1007/s10558-007-9047-3

Laura M Ellwein, Hien T Tran, Cheryl Zapata, Vera Novak, Mette S Olufsen

{"title":"Sensitivity analysis and model assessment: mathematical models for arterial blood flow and blood pressure.","authors":"Laura M Ellwein, Hien T Tran, Cheryl Zapata, Vera Novak, Mette S Olufsen","doi":"10.1007/s10558-007-9047-3","DOIUrl":"https://doi.org/10.1007/s10558-007-9047-3","url":null,"abstract":"The complexity of mathematical models describing the cardiovascular system has grown in recent years to more accurately account for physiological dynamics. To aid in model validation and design, classical deterministic sensitivity analysis is performed on the cardiovascular model first presented by Olufsen, Tran, Ottesen, Ellwein, Lipsitz and Novak (J Appl Physiol 99(4):1523-1537, 2005). This model uses 11 differential state equations with 52 parameters to predict arterial blood flow and blood pressure. The relative sensitivity solutions of the model state equations with respect to each of the parameters is calculated and a sensitivity ranking is created for each parameter. Parameters are separated into two groups: sensitive and insensitive parameters. Small changes in sensitive parameters have a large effect on the model solution while changes in insensitive parameters have a negligible effect. This analysis was successfully used to reduce the effective parameter space by more than half and the computation time by two thirds. Additionally, a simpler model was designed that retained the necessary features of the original model but with two-thirds of the state equations and half of the model parameters.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"8 2","pages":"94-108"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9047-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"27118594","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: 88

Arterial baroreflexes and cardiovascular modeling. 动脉压力反射和心血管模型。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-03-01 DOI: 10.1007/s10558-007-9042-8

Dwain L Eckberg

{"title":"Arterial baroreflexes and cardiovascular modeling.","authors":"Dwain L Eckberg","doi":"10.1007/s10558-007-9042-8","DOIUrl":"https://doi.org/10.1007/s10558-007-9042-8","url":null,"abstract":"Many cardiovascular models involve prediction of changes that occur when a subject is perturbed in some way, to move from one state to another. A successful, predictive model should involve at least two elements: First, the model should include some index of the intensity of the perturbation that elicits the response; effective responses should, in some fashion, be linearly or nonlinearity related to perturbations. Second, the model should factor in subjects' abilities to meet the challenges posed by the perturbations. This review indicates that these two basic components of a successful model may be difficult to incorporate. In the simple case of passive upright tilt, blood pressure measurements may not accurately indicate the stimulus, because blood pressure reductions are reversed by rapidly occurring reflex blood pressure increases. Since not all subject populations respond identically to hemodynamic challenges, it also may be important to characterize baroreflex responsiveness, and include such a term in a model. Although vagal and sympathetic baroreflex responses to stereotyped challenges can be measured accurately, recent research points to extraordinary variability of baroreflex responsiveness. The complexities discussed in this review should be considered, whether they are, or even can be incorporated into cardiovascular models.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":"8 1","pages":"5-13"},"PeriodicalIF":0.0,"publicationDate":"2008-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9042-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"27118518","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: 17

Variability in cardiovascular control: the baroreflex reconsidered. 心血管控制的变异性:重新考虑气压反射。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-03-01 DOI: 10.1007/s10558-007-9046-4

John M Karemaker, Karel H Wesseling

{"title":"Variability in cardiovascular control: the baroreflex reconsidered.","authors":"John M Karemaker, Karel H Wesseling","doi":"10.1007/s10558-007-9046-4","DOIUrl":"https://doi.org/10.1007/s10558-007-9046-4","url":null,"abstract":"Although blood pressure control is often viewed as a paradigmatic example of a \"homeostatic\" biological control system, blood pressure levels can fluctuate considerably over shorter and longer time scales. In modern signal analysis, coherence between heart rate and blood pressure variability is used to estimate baroreflex gain. However, the shorter the measurement period, the more variability this gain factor reveals. We review evidence that this variability is not due to the technique used for the estimation, but may be an intrinsic property of the circulatory control mechanisms. The baroreflex is reviewed from its evolutionary origin, starting in fishes as a reflex mechanism to protect the gills from excessively high pressures by slowing the heart via the (parasympathetic) vagus nerve. Baroreflex inhibition of cardiovascular sympathetic nervous outflow is a later development; the maximally possible extent of sympathetic activity probably being set in the central nervous system by mechanisms other than blood pressure per se. In the sympathetic outflow tract not only baroreflex inhibition but also as yet unidentified, stochastic mechanisms decide to pass or not pass on the sympathetic activity to the periphery. In this short essay, the \"noisiness\" of the baroreflex as nervous control system is stressed. This property is observed in all elements of the reflex, even at the--supposedly--most basic relation between afferent receptor nerve input and efferent--vagus--nerve output signal.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":" ","pages":"23-9"},"PeriodicalIF":0.0,"publicationDate":"2008-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9046-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41038580","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: 57

Receding horizon controller for the baroreceptor loop in a model for the cardiovascular system. 心血管系统模型中压力感受器回路的后退水平控制器。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-03-01 DOI: 10.1007/s10558-007-9043-7

Mark Mutsaers, Mostafa Bachar, Jerry Batzel, Franz Kappel, Stefan Volkwein

引用次数: 9

Modeling of autonomic control in sleep-disordered breathing. 睡眠呼吸障碍的自律神经控制模型。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-03-01 DOI: 10.1007/s10558-007-9041-9

Michael C K Khoo

{"title":"Modeling of autonomic control in sleep-disordered breathing.","authors":"Michael C K Khoo","doi":"10.1007/s10558-007-9041-9","DOIUrl":"10.1007/s10558-007-9041-9","url":null,"abstract":"There is ample evidence to support the notion that chronic exposure to repetitive episodes of interrupted breathing during sleep can lead to systemic hypertension, heart failure, myocardial infarction and stroke. Recent studies have suggested that abnormal autonomic control may be the common factor linking sleep-disordered breathing (SDB) to these cardiovascular diseases. We have developed a closed-loop minimal model that enables the delineation of the major physiological mechanisms responsible for changes in autonomic system function in SDB, and also forms the basis for a noninvasive technique that enables the early detection of cardiovascular control abnormalities. The model is \"minimal\" in the sense that all its parameters can be estimated through analysis of the data measured noninvasively from a single experimental procedure. Parameter estimation is enhanced by broadening the frequency content of the subject's ventilatory pattern, either through voluntary control of breathing or involuntary control using ventilator assistance. Although the original form of the model is linear and time-invariant, extensions of the model include the incorporation of nonlinear dynamics in the autonomic control of heart rate, and allowing the transfer functions of the model components to assume time-varying characteristics. The various versions of the model have been applied to different populations of subjects with SDB under different conditions (e.g. supine wakefulness, orthostatic stress, sleep). Our cumulative findings suggest that the minimal model approach provides a more sensitive means of detecting abnormalities in autonomic cardiovascular control in SDB, compared to univariate analysis of heart rate variability or blood pressure variability.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":" ","pages":"30-41"},"PeriodicalIF":0.0,"publicationDate":"2008-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3339254/pdf/nihms362442.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41056907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cerebral autoregulation: from models to clinical applications. 脑自动调节:从模型到临床应用。

Cardiovascular Engineering (dordrecht, Netherlands) Pub Date : 2008-03-01 DOI: 10.1007/s10558-007-9044-6

Ronney B Panerai

{"title":"Cerebral autoregulation: from models to clinical applications.","authors":"Ronney B Panerai","doi":"10.1007/s10558-007-9044-6","DOIUrl":"https://doi.org/10.1007/s10558-007-9044-6","url":null,"abstract":"Short-term regulation of cerebral blood flow (CBF) is controlled by myogenic, metabolic and neurogenic mechanisms, which maintain flow within narrow limits, despite large changes in arterial blood pressure (ABP). Static cerebral autoregulation (CA) represents the steady-state relationship between CBF and ABP, characterized by a plateau of nearly constant CBF for ABP changes in the interval 60-150 mmHg. The transient response of the CBF-ABP relationship is usually referred to as dynamic CA and can be observed during spontaneous fluctuations in ABP or from sudden changes in ABP induced by thigh cuff deflation, changes in posture and other manoeuvres. Modelling the dynamic ABP-CBFV relationship is an essential step to gain better insight into the physiology of CA and to obtain clinically relevant information from model parameters. This paper reviews the literature on the application of CA models to different clinical conditions. Although mathematical models have been proposed and should be pursued, most studies have adopted linear input-output ('black-box') models, despite the inherently non-linear nature of CA. The most common of these have been transfer function analysis (TFA) and a second-order differential equation model, which have been the main focus of the review. An index of CA (ARI), and frequency-domain parameters derived from TFA, have been shown to be sensitive to pathophysiological changes in patients with carotid artery disease, stroke, severe head injury, subarachnoid haemorrhage and other conditions. Non-linear dynamic models have also been proposed, but more work is required to establish their superiority and applicability in the clinical environment. Of particular importance is the development of multivariate models that can cope with time-varying parameters, and protocols to validate the reproducibility and ranges of normality of dynamic CA parameters extracted from these models.","PeriodicalId":55275,"journal":{"name":"Cardiovascular Engineering (dordrecht, Netherlands)","volume":" ","pages":"42-59"},"PeriodicalIF":0.0,"publicationDate":"2008-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10558-007-9044-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41038581","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: 260