心血管系统的电网络模型及其仿真算法

心输出量是心血管系统有价值的一项参数,它是进入人体体循环的血液流量的一个直接度量,因此它可用来衡量体内氧气及其它营养成分的输运能力。目前大多数用来估测心输出量的方法都是有损的,因而建立一种无损估测的方法是有意义的。这种无损方法必须简单易行,当然也必须是准确可靠的。在这方面的研究工作主要是首先建立心血管系统的电网络模型,而后根据模型的仿真结果估测心输出量以及其它重要的心血管系统参数。在建立模型方面,一种方法是通过对心血管系统的动力学分析,使用电网络中的阻抗和传输线来类比血管的分支,弹性等生理特性,…     

模拟心血管系统装置的研制及其在血液动力学测试中的应用

为研究心血管系统血液动力学特性和评测人工心脏,本文根据弹性腔模型建立了一套能反映血液动力学特性的体外血液循环模拟实验装置,测试血液动力学参量与心室后负荷(即外周阻力R和动脉顺应性C)以及每搏心输出量Vs,心动周期T,心室收缩时间间隔Ts和前负荷等六个参量之间的相互关系,通过改变六个参量的某一个参量而固定其余参量,测试这个参量对动脉血压及流量的影响情况.实验结果与生理情况和数学模型分析相符合,整个模拟装置能够反映血液动力学特性.     

体外模拟心血管系统血液动力学性能分析

为研究人工心脏和心血管系统之间的血液动力学作用机制．根据弹性腔模型建立了一套能反映血液动力学特性的体外血液循环模拟实验装置，测试血液动力学参量与心室后负荷（即外周力R和动脉顺应性C）以及每搏心输出量Vs，心动周期T和心室收缩时间间隔Ts，前负荷等六个参量之间的相互关系．通过改变六个参量中的某一个参量而固定其余参量，测试这个参量对动脉血压及流量的影响情况。实验结果与生理情况和数学模型分析相符合。压力和流量波呈脉动性，与真实生理波形相似。整个模拟装置能够反映血液动力学特性。     

对心阻抗血流图基本公式的重要修正

用心阻抗血流图ICG估算左心每搏输出量,是临床上已获得普遍应用的一种无创性测量技术。但是,这一技术的理论基础,是建立在一个与心血管生理不完全符合的假设之上的:从七十代沿用至今的、以ICG估算左心每搏输出量的方法,其基本理论和基本公式都是     

基于脉搏色素光密度法的心输出量测量系统

临床上心输出量(CO)等心血管血流动力学参数是心脏功能状况及心血管疾病的诊断依据,传统CO检测方法操作繁杂、有创伤以及患者术后易引发并发症。针对此问题,研究了一种基于脉搏色素光密度法的心输出量测量系统,以朗伯比尔定律和色素稀释理论为基础,通过选取合适的双波长探测光源(805nm/940 nm)实现了动脉吲哚氰绿(ICG)色素浓度谱的无创实时测量,从ICG浓度稀释曲线中计算出CO的数值。将本系统测量的值与当前测量CO的金标准热稀释法的结果进行对比,平均误差为4.79%,相关系数为0.99。实验结果表明:本研究所设计的心输出量测量系统实现了CO的无创、准确测量,可为临床检测CO提供一种新的选择。     

脉象与心血管动力学参数关系的实验研究

本文测定了60条雄性杂种狗的左侧桡动脉脉搏图和心血管动力学参数共17项。经过统计学处理发现不同脉象的心血管动力学参数有显著性差异,按照滑脉、平脉和弦脉的顺序,狗的心率、脉压、心输出量、血管顺应性(C)依次递减,外周阻力(R)依次递增。弦脉相应的心脏收缩射血功能减弱。在对参数分别进行多元线性回归分析后,获得了5个最优回归方程。结果表明,潮波高度与R之间,重搏波峰和谷的高度与C之间等均有良好的线性相关关系。     

用热稀释法直接测定左心输出量

在心血管系统的基础和临床研究中 ,常需要了解血液动力学状态 ,其中心输出量是重要指标之一。以往心输出量测定有两种主要方法 :Ｆｉｃｋ氏法和指示剂稀释法 ,其中 ,热稀释法测定心输出量具有其独特的优点 ,使其得到广泛应用。由于测定心输出量的Ｓｗａｎ -Ｇａｎｚ导管置于静脉系统内 ,其测定的心输出量实际为右心输出量。因肺循环与体循环的血流量是相等的 ,故可用右心输出量间接推断出等量的左心输出量[1 ,2 ,4] 。在基础和临床研究中 ,能否直接从动脉系统采用热稀释法直接测定左心输出量 ?就此 ,我们作了以下的研究。材　料　和　方　法…     

中医心气虚证的血液动力学机理研究

目的 心气虚是中医临床常见的病证，作者根据中医气血理论和对血液－组织液循环的分析建立了一个研究心气虚的血液动力学模型，从血液组织液循环角度阐述中医心气虚的动力学机理。方法 通过对模型的计算与分析得到了心血管系统动力学参数变化对全身气虚主要症状－组织间隙水肿的影响规律，给出了心血管动力学参数与气虚水肿程度间的定量关系。结果 将理论计算结果与临床和动物实验气虚证研究的比较发现，本模型可以定量解释中医心气虚的主要病理学机理。当心血管系统的参数（如血液总体积，外周阻力和心肌收缩特性等）发生改变时，会引起组织液的体积增大进而会导致组织液蛋白质和其他营养物质浓度的降低。结论 中医心气虚证中的气和组织液中营养物质浓度有密切相关，血液中的血浆和水过多地扩散到组织液间隙中会稀释组织液中的营养物质，使细胞的外环受到影响进而影响了细胞的生理功能，产生了气虚症状。     

基于心血管系统低阶模型的无创血压仿真与实验研究

目的：为仿真心血管系统血流情况，进而预测人体生理病理状态，并为无创连续血压检测系统的开发提供基础理论支持，本文详细阐述了一种心血管系统低阶仿真模型的分析以及建立过程。方法：在Windkessel模型的基础上．将心血管动脉管道视为一腔室系统，结合弹性腔模型基本方程以及心脏搏动间歇流模型建立起这段血管的一阶Simulink仿真模型，然后通过多普勒仪和柯氏音法检测受试人员每搏输出量及血压的实际值，据此计算出对应的模型参数．结果：将不同的模型参数代人该模型，以仿真受试人员在不同生理状态下的血压，仿真结果与临床测量到的生理值基本一致。结论：模型具有一定的实用性，能够模拟心血管系统血流情况，仿真不同生理情况下的心血管功能．后续工作可在此基础上展开。     

淋巴循环动力学模型研究

根据淋巴管的形态、功能、以及淋巴微循环调控机制的研究成果,在充分考虑血液、组织液和淋巴液相互作用的动态系统基础上,仿照Sungawa心输出量的分析方法,建立了一个描述淋巴循环的动力学模型,并将模型的理论研究结果与Ikomi的按摩对兔后腿淋巴流量影响的实验相对照,发现两者符合程度较高,表明该模型对于分析淋巴形成的动力学机制有一定的意义,特别分析了淋巴流量与按摩频率的关系,可用于临床分析推拿等外治疗法对淋巴循环的影响.     

Cardiovascular reactivity during performance under social observation: the moderating role of task difficulty.

An experiment with N=40 university students investigated the impact of social observation on cardiovascular reactivity during performance on a computer-based letter detection task. The study was conducted in a 2 (social observation: no vs. yes)x2 (task difficulty: easy vs. difficult) between-persons design. In accordance with engagement-related predictions about the role of social observation in active coping, the mere presence of an experimenter who observed participants during task performance increased the reactivity of systolic blood pressure when the task was difficult, but not when the task was easy. Without social observation, reactivity was modest in both the easy and the difficult conditions. Reactivity of diastolic blood pressure described the same pattern as systolic blood pressure. Results are interpreted as evidence for an effort-related analysis of cardiovascular reactivity based on the principles of motivational intensity theory.     

Systolic hypertension: the nephrologist's point of view

The elevation of systolic blood pressure associated with aging has been considered for years a physiologic phenomenon. This idea was based on the repeated observation that, also after middle age, a large majority of individuals in industrialized countries experience a continuous and progressive increase over time in systolic blood pressure, not in diastolic blood pressure. However, some individuals in industrialized countries and most individuals in nonindustrialized countries do not acquire an increased systolic blood pressure over time proving that the age-associated rise in systolic blood pressure is not an inevitable phenomenon. The change in systolic blood pressure over time strongly reflects lifestyles. Diet-dependent factors such as body weight, alcohol intake, and balance between dietary salt and potassium, are important in favoring the age-associated increase in systolic blood pressure, independently of several confounders. Epidemiologic studies suggest that elevation of systolic blood pressure is a risk factor for cardiovascular diseases: it relates to high incidence of lethal and nonlethal cardiovascular events also in the presence of diastolic blood pressure in the nonhypertensive range. Controlled clinical trials show that the treatment of isolated systolic hypertension reduces the number of cardiovascular events. In addition to cardiovascular disease, systolic blood pressure relates also to microalbuminuria, an index of early glomerular damage, to long-term incidence of end-stage renal disease, and, in hemodialyzed patients, to premature death. Thus, high systolic blood pressure appears an unhealthy condition also for patients with or at risk for kidney diseases.     

Differential control of systolic and diastolic blood pressure in blacks with essential hypertension

OBJECTIVE: The risk of cardiovascular and renal diseases has been shown to be higher for systolic blood pressure than diastolic blood pressure. The aim of this study was to assess the differential control of systolic and diastolic blood pressure in Nigerians with primary hypertension. DESIGN AND SETTING: This was a prospective observational study carried out at the Medical Outpatient Department of the State Hospital, Abeokuta, Nigeria. Ethical approval for the study was obtained from the ethical committee of the hospital. METHODOLOGY: The study population consisted of 185 consecutive patients (65 males, 120 females), aged 35-85 years with primary hypertension who had been on drugs one- to 25 years prior to the onset of the study. Clinic blood pressure control was assessed during a year period. Six consecutive clinic blood pressure readings were recorded for each patient and the average calculated (systolic blood pressure and diastolic blood pressure separately). Patients were classified into subgroups based on the pattern of blood pressure control. RESULTS: Clinic systolic blood pressure and diastolic blood pressure was controlled in 58 patients (31.4%). Systolic blood pressure control was less frequent than diastolic blood pressure control (35.7% versus 51.4%, p<0.05). Patients with uncontrolled systolic blood pressure were significantly older than patients with only uncontrolled diastolic blood pressure (66.7+/-7.4 versus 52.9+/-8.7 years, p<0.001). CONCLUSION: Systolic blood pressure is less frequently controlled than diastolic blood pressure in Nigerians treated for primary hypertension. This may increase the patient's risk of developing stroke, and cardiovascular and renal complications.     

A meta-analytic examination of basal cardiovascular activity in posttraumatic stress disorder

OBJECTIVE: The objective of this meta-analytic study was to determine whether individuals with posttraumatic stress disorder (PTSD) have higher levels of basal cardiovascular activity relative to comparable groups of individuals without PTSD. METHODS: Meta-analytic data methods were applied to 34 studies that gathered indicators of basal cardiovascular activity including: heart rate (HR), systolic blood pressure, and diastolic blood pressure on subjects diagnosed with PTSD and two types of comparison groups. In total, cardiovascular measures were analyzed for 2670 subjects across all studies. RESULTS: Results indicate that individuals with a current PTSD diagnosis have higher resting HR relative to both trauma-exposed individuals without a PTSD diagnosis and non-trauma-exposed individuals. The results also suggest that PTSD is associated with elevations in blood pressure; however, the effect sizes were smaller in magnitude than those obtained for heart rate. A subset analysis revealed that the effect sizes for comparisons on basal HR were greatest in studies with the most chronic PTSD samples. CONCLUSION: The meta-analysis supports previous qualitative reviews, finding a positive association between PTSD and basal cardiovascular activity. The discussion addresses possible mechanisms of action and the health-related implications of these findings.     

基于脉搏波的新型血压与血管硬度测量仪的研制

目的：根据脉搏波理论研制出一种新型血压与血管硬度测量仪。方法：利用示波法原理在波形特征法和幅度系数法的基础上提出一种系数差分比值法来间接测量血压的新方法，通过采集肱动脉和桡动脉两处波形，获得了脉搏波传播速度（PWv）、动脉顺应性（C1、C2）和动脉硬化指数（ASI）三个反映受试者动脉弹性的参数指标。结果：通过大量病例分析和临床测试证实了算法的有效性和可靠性，而且此算法已经应用LabVIEW开发成软件并在医院进行临床应用。结论：血压与血管硬度检测仪能判断心血管病患者与正常人的差异性，对我国心血管病方面流行病学的调查、疾病预防、疾病早期发现都具有很大的意义。     

Influence of ambulatory blood pressure-related indicators within 24 h on in-hospital death in sepsis patients

Background: Sepsis is a serious public health problem worldwide. Blood pressure is one of the indicators that is closely monitored in intensive-care units, and it reflects complex interactions between the internal cardiovascular control mechanism and the external environment. We aimed to determine the impact of indicators related to the ambulatory blood pressure on the prognosis of sepsis patients.Methods: This retrospective study was based on the Medical Information Mart for Intensive Care IV database. Relevant information about sepsis patients was extracted according to specific inclusion and exclusion criteria. Examined parameters included the average blood pressure, blood pressure variability (BPV), and circadian rhythm, and the study outcome was in-hospital death. We investigated the effects of these indicators on the risk of in-hospital death among sepsis patients using Cox proportional-hazards models, restricted cubic splines analysis, and subgroup analysis.Results: This study enrolled 10,316 sepsis patients, among whom 2,117 died during hospitalization. All parameters except the nighttime variation coefficient of the diastolic blood pressure (DBP) were associated with in-hospital death of sepsis patients. All parameters except for fluctuations in DBP exhibited nonlinear correlations with the outcome. The subgroup analysis revealed that some of the examined parameters were associated with in-hospital death only in certain subgroups.Conclusion: Indicators related to the ambulatory blood pressure within 24 h are related to the prognosis of sepsis patients. When treating sepsis, in addition to blood pressure, attention should also be paid to BPV and the circadian rhythm in order to improve the prognosis and the survival rate.     

Impact of high-normal blood pressure on the risk of cardiovascular disease.

BACKGROUND: Information is limited regarding the absolute and relative risk of cardiovascular disease in persons with high-normal blood pressure (systolic pressure of 130 to 139 mm Hg, diastolic pressure of 85 to 89 mm Hg, or both). METHODS: We investigated the association between blood-pressure category at base line and the incidence of cardiovascular disease on follow-up among 6859 participants in the Framingham Heart Study who were initially free of hypertension and cardiovascular disease. RESULTS: A stepwise increase in cardiovascular event rates was noted in persons with higher baseline blood-pressure categories. The 10-year cumulative incidence of cardiovascular disease in subjects 35 to 64 years of age who had high-normal blood pressure was 4 percent (95 percent confidence interval, 2 to 5 percent) for women and 8 percent (95 percent confidence interval, 6 to 10 percent) for men; in older subjects (those 65 to 90 years old), the incidence was 18 percent (95 percent confidence interval, 12 to 23 percent) for women and 25 percent (95 percent confidence interval, 17 to 34 percent) for men. As compared with optimal blood pressure, high-normal blood pressure was associated with a risk-factor-adjusted hazard ratio for cardiovascular disease of 2.5 (95 percent confidence interval, 1.6 to 4.1) in women and 1.6 (95 percent confidence interval, 1.1 to 2.2) in men. CONCLUSIONS: High-normal blood pressure is associated with an increased risk of cardiovascular disease. Our findings emphasize the need to determine whether lowering high-normal blood pressure can reduce the risk of cardiovascular disease.     

Comparing the association of cardiovascular nursing care with blood pressure and length of stay of in-patients with coronary artery disease in Wuhan,China

BackgroundCoronary artery disease is a leading cause of morbidity and mortality worldwide. Comorbidity-like hypertension has been among the major risks of coronary artery disease. Recent evidence identified multiple benefits of cardiovascular nursing care to coronary patients. However, little has been appraised on benefits regarding patients'' blood pressure control and length of hospitalisation.ObjectiveTo compare the association of cardiovascular nursing care delivered to coronary artery patients with patients'' blood pressure and length of stay.MethodsRecords based retrospective design was applied at a large teaching hospital in Wuhan, China. SPSS 21 version was used for data entry and analysis with univariate and multivariate logistic regression models for comparing study variables.ResultsOf 300 patients, 224 (74.7%) were known to be hypertensive and admitted with subnormal blood pressure. Cardiovascular nursing care like “assess to grade pain severity on 1–10 scale” and “counsel patient to cope with stress” were six and three times more likely to contribute improved patients'' blood pressure (AOR=5.8; 95%CI: 2.8–12.2, p=0.001) and (AOR=3.1; 95%CI: 1.2–7.8, p=0.015) respectively. No significant difference with length of stay (p>0.05).ConclusionThere is a possibility of coronary artery patients to recover with normal blood pressure following reception of evidence-based cardiovascular nursing care.     

Ambulatory blood pressure responses and the circumplex model of mood: a 4-day study.

BACKGROUND: The relation between mood or emotions and concurrent ambulatory blood pressure responses holds both fundamental and clinical interest. METHODS: The primary sample consisted of 69 normotensive or borderline hypertensive but otherwise healthy adult males. The validation sample consisted of 85 healthy male undergraduate college students. Both samples underwent half-hourly 24-hour ambulatory blood pressure measurements on four separate workdays, 1 week apart. At each ambulatory measurement, subjects recorded their behavior, environment, and mood. The circular mood scale, a circular visual analogue scale based on the circumplex model of mood, was used to reflect the totality of a participant's affective state space. Longitudinal random effects regression models were applied in the data analysis. RESULTS: The results for both samples were quite similar. Sleep and posture had the greatest influence on ambulatory blood pressure and heart rate. The effects of the environmental setting, social setting, and consumption were modest but statistically significant. Independent of these covariates, mood exerted a significant effect on blood pressure and heart rate. Relative to the "mellow" default category, blood pressure increased both for "anxious/annoyed" and "elated/happy" and decreased during "disengaged/sleepy" mood. The range of mood-related blood pressure estimates was 6.0/3.7 mm Hg. CONCLUSIONS: The pattern of blood pressure responses suggests that they were related to the degree of engagement of a mood rather than the degree of unpleasantness. The hypothesis that posits that negative affect-related cardiovascular reactivity mediates the observed correlation between negative affect and disease risk should be reconsidered.     

Increased blood pressure reactions to acute mental stress are associated with 16‐year cardiovascular disease mortality

Exaggerated cardiovascular reactions to acute psychological stress may be involved in the etiology of cardiovascular pathology. The present analysis examined the association between the magnitude of systolic and diastolic blood pressure reactions to stress and cardiovascular disease mortality. Participants were 431 (229 women) from the West of Scotland Twenty‐07 Study, aged 63 years at the time of stress testing, where blood pressure was measured during resting baseline and mental arithmetic stress. Participants' vital status was tracked for the next 16 years, during which time 38 had died of cardiovascular disease. Both systolic and diastolic blood pressure reactions were positively associated with cardiovascular disease mortality. This association could reflect the long‐term erosive effects of exaggerated reactivity on the vasculature as well as its short‐term capacity to trigger acute cardiovascular events.