心音图自动识别算法的设计研究

目的：开发出实现心音自识别的算法,通过该算法对输入的心音信号进行识别、降噪、包络提取及定位等系列操作,获得真实平滑的心音包络曲线,并在曲线上定位第一心音、第二心音等心音参数。方法：采用Matlab平台设计,对模拟心音信号进行重采样后,通过高通滤波进行信号的降噪,使用小波分解等方法获取平滑且不失真的心音包络曲线,并对所得包络曲线进行双阈值定位,找出心音特征点,并计算相关参数。结果：算法可以获取平滑的心音包络,包络线能真实反映心音的情况,并可由此进行高精度的心音定位,获取第一、第二心音的持续时间,计算心率、心音时限比等参数,为医生的心音诊断提供依据。结论：算法可实现对心音的自动定量分析,并通过阈值降噪等方法减少识别误差。相比于传统心音听诊,具有可观性强,频带宽等特点,并可记录患者的病理特征,通过治疗前后的对比为诊疗过程提供评估依据,相较于传统的心音听诊,算法的引入能够降低医生主观因素带来的诊断误差,使诊断结果客观可靠。     

Influence of beliefs about heart rate and actual heart rate on heartbeat counting

The heartbeat counting task is used widely to assess the ability to perceive cardiac sensations. However, performance on this task may be determined by processes other than sensitivity to cardiac stimuli. Beliefs about the effects of postural and exercise challenges on heart rate were assessed by questionnaire prior to performing the heartbeat counting task, and then actual heart rate was manipulated during the counting task by changes in posture and exercise. On average, counted heart rates were closer to beliefs about heart rate than to actual heart rate. Hierarchical multiple regression analyses indicated that (a) believed heart rates predicted counted heart rates while controlling for actual heart rates and (b) actual heart rates also predicted counted heart rate while controlling for heart rate beliefs. These data suggest that the rate of heartbeat counting is influenced by beliefs about heart rate and by the processing of cardiac sensations.     

The effect of chronic anxiety level upon self control of heart rate

A sample of 90 subjects were rated on the IPAT anxiety scale and 5 subjects (3 male and 2 female) per group were selected from each of the high and low anxiety categories. All subjects were naive participants in heart rate biofeedback sessions utilising analogue visual feedback. Following a heart rate baseline (no feedback) session, all subjects were required to raise their heart rate and lower their heart rate in two separate trials, a visual ‘target’ criteria being provided. The data collected consisted of a resting baseline heart rate value, mean heart rate increase, and mean heart decrease values expressed as beats per minute. Results indicated a marked ability for highly anxious subjects to self-induce heart rate increases only and for low anxious subjects to decrease their heart rate only.     

Noninvasive tests in the initial evaluation of heart murmurs in children

We prospectively examined the usefulness of electrocardiography, chest radiography, and M-mode echocardiography in discriminating between the presence and absence of heart disease in 280 children older than one month and newly referred for evaluation of a heart murmur. After taking a history and performing a physical examination but before reviewing diagnostic tests, we categorized the children as having "no heart disease" (142), "possible heart disease" (34), or "definite heart disease" (104). Among the children initially thought to have no heart disease, the diagnosis was changed after a review of diagnostic tests in eight--three with mitral-valve prolapse, two with possible cardiomyopathy, and three with no heart disease on follow-up. Among those initially thought to have possible heart disease, the tests changed the diagnosis to definite heart disease in four, of whom only one had heart disease (mitral-valve prolapse) on follow-up. In no case did a review of tests change the diagnosis of definite heart disease. We conclude that the results of diagnostic tests are unlikely to change the clinical diagnosis of no heart disease or definite heart disease, when made by a qualified pediatric cardiologist in children newly referred for evaluation of a heart murmur.     

构建基于正常人心脏解剖及影像数据的动态心脏模型

目的　构建基于正常心脏数据的三维动态心脏模型。 方法　采集正常成人心脏数据,通过Microsoft Visual C++和3DMax软件重建生成心脏三维模型,并将正常心电图与之整合,同步显示心脏运动。 结果　建立了数字化心脏可视动态模型,能够反映心脏三维形状和内腔结构,并可与心电图同步运动。 结论　动态心脏模型能够为心脏结构与运动的教学及疾病分析提供可视化的数值仿真平台。     

Age-related analysis of structural,biochemical and mechanical properties of the porcine mitral heart valve leaflets

Abstract

The aim of this study was to assess structural and biochemical differences in the extracellular matrix of the fetal and adult porcine mitral heart valves in relation to their mechanical characteristics. Using tensile tests it was demonstrated that the material properties of porcine mitral heart valves progressively change with age. The collagen content of the adult heart valve, as estimated by hydroxyproline assay, increases three times as compared with fetal heart valves. Transmission electron microscopy demonstrated that the diameter of collagen fibrils increased in adult heart valves compared with fetal heart valves. The level of collagen cross-linking is lower in the fetal heart valve than the adult heart valve. The reported age differences in the material properties of fetal and adult porcine heart valves were associated with increases in collagen content, the diameter of collagen fibrils and the level of collagen cross-linking. These data lay a foundation for systematic elucidation of the structural determinants of material properties of heart valves during embryonic and postnatal valvulogenesis. They are also essential to define the desirable level of tissue maturation in heart valve tissue engineering.     

The metrics of cardiac chronotropism: Biometric perspectives

The selection of heart period versus heart rate as a chronotropic metric has been considered from quantitative and statistical perspectives, which have not yielded a universal preference for either metric. In the present paper, we discuss biometric considerations that bear on the selection of the optimal chronotropic metric. Biometric evidence reveals that the transfer functions relating autonomic nerve traffic to chronotropic effects on the heart are more nearly linear for heart period than for heart rate. This confers considerable advantage on heart period as a chronotropic metric and can facilitate the study of psychophysiological relationships. We further show that heart period offers greater flexibility, because heart period data can be evaluated in cardiac time units (beats) or in real-time units (s), whereas heart rate data can only be analyzed in real time. These considerations suggest clear advantages to heart period as a chronotropic metric.     

Accuracy of the LifeShirt (Vivometrics) in the detection of cardiac rhythms

The use of heart rate measures in research requires accurate detection and timing of beat-to-beat values. Numerous technologies are available to researchers; however, benchmarking of a specific apparatus is seldom conducted. Since heart rate variability provides a portal to the neural regulation of the heart, accurate detection and timing of beat-to-beat values is essential to both basic physiological research and the clinical application of heart rate variability measures. The current study evaluated the accuracy of an ambulatory system, the LifeShirt (Vivometrics), relative to a standard laboratory-based heart rate monitoring equipment (Biopac), during baseline and exercise conditions. LifeShirt performed equivalently to the Biopac during both conditions, experienced few errors of detection, generated similar times between sequential heart periods, and produced similar summary indices of heart rate and heart rate variability.     

基于数学形态学的心音包络提取与识别方法研究

心音包络比原始心音可以更好地显示心音的特征,是进行心音独立识别的基础.本文把数学形态学应用于心音包络的提取和识别的研究.首先利用形态学滤波和全波整流对原始心音进行预处理;然后利用形态学闭运算提取心音包络;最后应用形态学开运算来消除噪声包络.在数学形态学提取的心音包络基础上,对50例心音样本进行了第一心音、第二心音识别,全部20例正常心音的第一心音和第二心音被正确识别,27例包含心杂音的异常心音的第一心音、第二心音也被正确识别.为进一步的心音分析及心音诊断奠定了基础.     

Application of tissue-engineering principles toward the development of a semilunar heart valve substitute

Heart valve disease is a significant medical problem worldwide. Current treatment for heart valve disease is heart valve replacement. State of the art replacement heart valves are less than ideal and are associated with significant complications. Using the basic principles of tissue engineering, promising alternatives to current replacement heart valves are being developed. Significant progress has been made in the development of a tissue-engineered semilunar heart valve substitute. Advancements include the development of different potential cell sources and cell-seeding techniques; advancements in matrix and scaffold development and in polymer chemistry fabrication; and the development of a variety of bioreactors, which are biomimetic devices used to modulate the development of tissue-engineered neotissue in vitro through the application of biochemical and biomechanical stimuli. This review addresses the need for a tissue-engineered alternative to the current heart valve replacement options. The basics of heart valve structure and function, heart valve disease, and currently available heart valve replacements are discussed. The last 10 years of investigation into a tissue-engineered heart valve as well as current developments are reviewed. Finally, the early clinical applications of cardiovascular tissue engineering are presented.     

大鼠离体作功心脏对冠脉压强变化的反应

目的:研究离体作功心脏对其冠脉压强变化的反应.方法:采用分离式离体作功心脏模型.用上海产SJ-42型四导生理记录仪测定生理参数左心室收缩压LVSP,左心室内压上升的最大速率(dp/dt)max,冠脉流量CF,心率HR和心电图ECG.结果:离体作功心脏的工作状态受其冠脉压强变化的影响,当灌注压Pc=9 kPa时,心脏处于最佳状态.灌注压过高或过低均可导致心脏功能减弱.结论:心脏自身存在冠脉压强感受系统,在冠脉压强发生变化时,心脏自主地调节着工作状态.     

肺心病左室舒张功能障碍发病机制的研究进展

近年来肺心病的发病率逐年上升,以往认为肺心病对心脏的影响主要以右心功能障碍为主,不影响左心功能,左心功能障碍主要为原发左心病变所致,但近年来不少文献指出由慢阻肺长期发展引起的肺心病在早期即可合并左心功能障碍,主要以左室舒张功能障碍为主。本文主要从五个不同方面阐述由慢阻肺长期发展引起的肺心病患者左室舒张功能障碍的原因,结合相关文献做一综述。     

心脏Telocytes在年老大鼠心脏的分布

目的探讨心脏Telocytes(CTs)在年老大鼠心脏的形态、分布及与年青心脏比较的异同。方法使用透射电子显微镜、生物测量、免疫荧光染色等技术,对24月龄年老大鼠心脏的心房部分、心室中间部分及心尖部分的代表性横切面中,CTs的形态、分布与细胞密度进行半定量分析。结果年老心脏3个代表性横切面的心肌细胞间隙和微血管周边均存在许多CTs,上述3个不同部位的CTs的形态指标的半定量分析值十分接近,差异没有统计学意义。经分离的年老心脏CTs与年青心脏一样表达c-Kit和CD34。对3个代表性横切面CTs细胞密度的半定量分析结果显示,年老大鼠心房部分的CTs密度[(47.65±4.01)个/mm~2]显著高于心尖部分[(33.68±2.53)个/mm2]和中间部分[(26.49±2.11)个/mm~2](P0.05)。年老心脏CTs在上述区域分布的差异,与我们前期所观察到的年青大鼠心脏相应区域CTs的分布规律相一致[7],但年老心脏上述3个区域CTs的密度均显著性高于年青心脏对应区域(P0.05)。结论年老心脏存在CTs,其心房部分的CTs密度显著高于心尖部分和心室中间部分,该分布规律与年青大鼠相一致,但年老心脏上述区域CTs的密度显著高于年青心脏。     

川芎水煎液对离体蟾蜍心功能的影响

目的：观察川芎水煎液对蟾蜍离体心脏收缩性、自律性和心输出量的影响。方法：采用八木氏法蛙心灌流标本，分别灌流不同浓度的川芎水煎液。结果：1μg·m^-1、10μg·ml^-1。的川芎水煎液几乎不改变心缩力，而100μg·ml^-1、500μg·ml^-1、1000μg·ml^-1。川芎水煎液呈现明显的负性变力作用，心缩力与浓度显著负相关（r=-0．792，P〈O．01）；心输出量与心缩力平行改变；不同浓度川芎水煎液对心自律性改变，差异未达统计意义（P〉O．05）。结论：川芎水煎液降低离体蛙心的心缩力和心输出量，且有明显量效关系。     

心脏建模仿真研究进展

本文综述了近年来国际上在不同层次上心脏建模仿真的研究成果和进展 ,分别介绍了亚细胞和细胞层次、组织和器官层次上的心脏电生理模型、机械力学模型和生物化学模型。最后 ,简要地分析了心脏建模存在的问题并展望了心脏建模仿真领域今后的发展趋势     

Detection of the third heart sound using a tailored wavelet approach

The third heart sound is normally heard during auscultation of younger individuals but disappears with increasing age. However, this sound can appear in patients with heart failure and is thus of potential diagnostic use in these patients. Auscultation of the heart involves a high degree of subjectivity. Furthermore, the third heart sound has low amplitude and a low-frequency content compared with the first and second heart sounds, which makes it difficult for the human ear to detect this sound. It is our belief that it would be of great help to the physician to receive computer-based support through an intelligent stethoscope, to determine whether a third heart sound is present or not. A precise, accurate and low-cost instrument of this kind would potentially provide objective means for the detection of early heart failure, and could even be used in primary health care. In the first step, phonocardiograms from ten children, all known to have a third heart sound, were analysed, to provide knowledge about the sound features without interference from pathological sounds. Using this knowledge, a tailored wavelet analysis procedure was developed to identify the third heart sound automatically, a technique that was shown to be superior to Fourier transform techniques. In the second step, the method was applied to phonocardiograms from heart patients known to have heart failure. The features of the third heart sound in children and of that in patients were shown to be similar. This resulted in a method for the automatic detection of third heart sounds. The method was able to detect third heart sounds effectively (90%), with a low false detection rate (3.7%), which supports its clinical use. The detection rate was almost equal in both the children and patient groups. The method is therefore capable of detecting, not only distinct and clearly visible/audible third heart sounds found in children, but also third heart sounds in phonocardiograms from patients suffering from heart failure.     

第3代人工心脏泵研究进展及应用

心力衰竭死亡率极高,患病数量持续攀升,是当今医学界面临的共同难题,人工心脏泵是众多心衰患者延长生存期最后的希望和最有效的途径。第3代人工心脏泵的开发与应用,将心力衰竭治疗推向一个新台阶。首先概述第3代人工心脏泵的研究现状和应用情况,并介绍国内第3代人工心脏泵的发展状况;其次,详述和总结第3代人工心脏泵相关的关键技术,如:悬浮技术、无轴承电机、泵用控制算法、叶轮优化设计、血液相容性等;最后,提出并探讨小型轻量化、仿生搏动性、智能控制技术、血液相容性、可靠性及容错技术等方面的研究趋势。     

Excitation and inhibition of the heart of the snail, Lymnaea, by non-FMRFamidergic motoneurons

1. The present paper extends the model of neuronal control of the Lymnaea heart by the use of intracellular recording techniques to identify further types of cardioactive neurons in the CNS that, like the previously described E heart excitor (Ehe) cells, influence the myogenic heartbeat. 2. Four new types of neuron that act on the heart are described. These are excitatory Hhe and She cells (H and S heart excitors) and the inhibitory Khi cell (K heart inhibitor). The fourth class, tonus pericardium excitor (Tpe), modulates the heart by action on pericardial tissue. 3. Pharmacologic, electrophysiological, and anatomic evidence is presented that shows that these cells are motoneurons, innervating heart muscle fibers directly: blocking central chemical synapses failed to prevent the actions of the neurons on the heart; simultaneous intracellular recordings showed unitary EJPs in heart muscle after 1:1 and with constant delay from evoked neuronal action potentials; intracellular injection of the dye Lucifer yellow showed all cells had axonal branches entering the intestinal nerve (which innervates the heart). 4. The use of selective antagonists to 5-hydroxytryptamine (5-HT) (cinanserin), dopamine (ergonovine), and acetylcholine (alpha-bungarotoxin) provided evidence that the actions of She and Hhe cells are mediated by 5-HT, whereas those of the Khi cell are mediated by acetylcholine. 5. A cyclically active network of three interneuronal inputs acting on the heart motoneurons is described. 6. One of these, input 3, is responsible for periodic excitation of the heart via its effects on the Hhe cells.     

Autonomic Interactions in the Control of Heart Rate in the Monkey

Each of 5 monkeys (Macaca mulatta) was operantly conditioned to raise and to lower heart rate consistently and reliably. Following such training the animals were tested using autonomic blocking agents (methyl-atropine bromide and 1-propranolol) to characterize the autonomic mechanisms mediating such control. The results were: 1) In the undrugged animal the extent to which it decreases its heart rate over a 2048-sec period is a linear function of the baseline heart rate; 2) A linear relationship between baseline heart rate and heart rate decrease also is present within the first 128 sec; 3) There is a less consistent relationship between baseline heart rate and change in heart rate when animals must increase heart rate; 4) Vagal blockade significantly attenuates the ability of most animals to increase heart rate, primarily by reducing their ability to produce large, relatively rapid increases; 5) Sympathetic blockade significantly attenuates the ability of most animals to increase heart rate both in terms of overall changes and in terms of large, relatively rapid responses; 6) Vagal blockade very significantly attenuates the ability of all animals to slow heart rate; 7) Sympathetic blockade facilitates the ability of most animals to slow heart rate. These findings show that both branches of the autonomic nervous system participate in the operant control of heart rate. The relative role of one branch or the other in a given experiment will depend upon the baseline conditions at the time of testing, and upon the requirements—i.e., raising or lowering of heart rate.     

心音信号的分析及其特征提取方法的研究

心音的改变和心脏杂音的出现，往往是器质性心脏病的最早体征。本研究讨论了一种全面的、综合性的心音信号分析方法，从多个角度对方法进行了探讨，提取心音的特征值，区分不同的心音。分析和仿真结果证明该方法能有效地区分不同的心音，有助于器质性心脏病的辅助诊断。