In vivo elastic modulus of the left ventricle: Its determination by means of a left ventricular vibrational model and its physiological significance and clinical utility

A quantitative estimate of the left ventricular muscle'sin vivo elasticity, as given by the Young's modulusE of the left ventricular muscle medium characterises resistance to left ventricular filling during diastole, contractile effort of the left ventricle, at the instant of opening of the aortic valve and myocardial diseases, such as myocardiopathy. This paper aims to provide the pertinent analysis (and in particular its, results in the form of nomograms) that can be employed, in conjunction with closed-chested data-acquisition methods, to obtainin vivo values of the effective modulus of left ventricular muscle medium. A vibrational analysis of the left-ventricle chamber model is developed to obtain the values of the primary freqeencies of vibration in terms of the dimensions of the model and the modulusE. On obtaining the values of the model dimensions (by matching the model volume and mass with the left-ventricle dimensions obtained from cineangiocardiography), and of the frequency associated with the maximum energy content of the pertinent heart sound, we can employ the analysis to determine the instantaneous value of the modulusE of the left ventricle. Our paper hence presents data acquisition for developing the model, analysis of the left ventricular model to yield ready-for-use nomograms givingE for prescribed heart sound frequency and the procedure for clinical use of the nomograms and clinical application of the model.     

Elastic modulus of the human intact left ventricle—determination and physiological interpretation

The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterised in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these peerformance variables, and hence represents the transfer function of the left ventricular physiological system. A method is presented for indirectly determining the effective modulusE for the left ventricle. The method employs a thick-walled mathematical model of the l.v. having a homogeneous isotropic medium. Instantaneous values ofE are determined for subjects with heart diseases of varied etiologies, in order to assess the responses of the l.v. to chronic overloads of pressure and volume. Resulting values forE are used diagnostically to characterise the physiological state of the l.v. Normal values ofE, at systole, indicate that the strength of contraction exercised by the l.v. is normal, and hence is an indication of the l.v. having adjusted to the heart disease.     

In vivo measurement of the elastic modulus of the human periodontal ligament.

The present study was designated to determine the elastic properties of the periodontal ligament (PDL) in human subjects. A maxillary central incisor was experimentally translated so that stress or strain could be uniformly distributed in the PDL by applying a single force passing through the center of resistance. Displacements were measured under different magnitudes of load using a magnet-magnetic sensing system. From the load-displacement relations, Young's modulus of the PDL was calculated. The values determined were approximately 0.12 MPa under load ranging from 0 to 0.5 N, 0.25 MPa within the range of 0.5-1.0 N, 0.44 MPa under load 1.0-1.5 N, and between 0.69 and 0.96 MPa with 1.5-2.0 N. The values of Young's moduli increased almost exponentially with the increment of load due to a non-linear elasticity of the PDL.     

Post-myocardial infarction exercise testing: clinical significance of a left ventricular function index and ventricular arrhythmias. A prospective study

A predischarge exercise test was performed in a prospective series of 187 patients, less than 70 years old, with acute myocardial infarction. A survival analysis confirmed previous retrospective findings of a significantly increased long-term mortality in patients with a low increase in the pressure-rate-product (PRP) and/or with major exercise-induced arrhythmias. ST segment depression was without prognostic significance. By a graduated, quantitative re-evaluation of the significance of exercise-induced ventricular arrhythmias, an appropriate, significantly discriminating cutoff point for the frequency of solitary ventricular premature beats (VPBs) was found at two or more VPBs/min. Repetitive VPBs had an equal significance. The probability of 4.5-year survival in patients with these arrhythmias and a low increase in PRP was 0.49 vs. 0.85 in patients with less frequent arrhythmias and with a high increase in PRP (p less than 10(-6)).     

In vivo determination of mechnical properties of the human ulna by means of mechanical impedance tests: Experimental results and improved mathematical model

An experimental technique and associated apparatus for measuringin vivo the mechanical impedance of the human ulna are described in detail. An electromagnetic shaker is used to apply a steady-state harmonic excitation to the ulna near its mid-span and measurements of the complex driving-point impedance are made. Both stiffness and resonant frequency information, useful in assessing the mechanical integrity of bone, are inferred from the impedance measurements by means of a third-generation mathematical model of the system. Results for three male and two female test subjects are reported.     

Pressure-volume relations,elastic modulus,and contractile behaviour of the hypertrophied left ventricle of rats with Goldblatt II hypertension

Summary In young male Wistar rats, an increase in systolic blood pressure to above 200 mm Hg was induced by constricting one renal artery (Goldblatt II). This led to cardiac hypertrophy with an increase in left ventricular weight of about 40% after 4 weeks as compared with controls of the same age. Four and 8 weeks after the operation, the systolic and enddiastolic pressure-volume relations of the left ventricle were determined under isovolumetric conditions in open-chest Goldblatt rats and in control animals of the same age. The systolic and diastolic wall stress and the tangential elastic modulus were calculated, assuming a thick-walled sphere. The diastolic pressure-volume curves were shifted to greater volumes after 4 weeks, apparently due to a temporary augmentation of blood volume. However, no significant difference between the diastolic pressure-volume curves of Goldblatt and control ventricles was found after 8 weeks. The isovolumetrically developed pressure was found to be increased in both stages of Goldblatt hypertension at the optimum of the pressure-volume diagram (maximum distance between end-diastolic and systolic pressure-volume curves). The diastolic wall stress rose only after 4 weeks in the hypertrophied ventricles due to the additional volume load. For a given diastolic wall stress, the elastic modulus tended to higher values in the Goldblatt hearts. Sarcomere length was measured after 8 weeks at the same end-diastolic transmural pressure at which the heart works in the closed chest. There was no significant difference between sarcomere length in the left ventricles of Goldblatt rats (1.99±0.03 μm) and control animals . The peak systolic wall stress, calculated from after loaded contractions, was not enhanced. However, the developed isovolumetric stress and the rate of stress development showed a significant increase in Goldblatt rats. These results indicate that the work capacity of the hypertrophied ventricle as a whole is enhanced. This enhancement of the contractile force per unit of cross-sectional area and its first derivative does not, however, allow the conclusion that there is an improvement in the elementary contractile process as the maximum myocardial shortening velocity at zero load (V _max) is decreased whilst the content of contractile proteins is augmented. Supported by the Deutsche Forschungsgemeinschaft     

室间隔缺损的解剖分型及其临床意义

目的：探讨室间隔缺损解剖分型的临床意义。方法：按照Ｓｏｔｏ的分类方法略加改进，将３５０例室间隔缺损分为４个解剖类型，并与其临床表现相对照。结果：３５０例室间隔缺损中，７６％（２６６例）为膜周型，缺损均与室间隔膜部关连；１９．４％（６８例）为干下型，位于肺动脉与主动脉相遇的左右瓣环下；０．９％（３例）为肌型，可见于肌部间隔的任何一处；３．７％（１３例）为混合型，包括单个大型缺损涉及室间隔多个部位或同时出现两种以上的单个室间隔缺损。描述了各型室间隔缺损的主要临床征象。外科医生可据此选择合适的手术切口及手术方法。结论：室间缺损的解剖分型对其临床诊断及治疗有较高的价值     

Mechanical support of the left ventricle in ischemia induced left ventricular failure: an experimental study.

OBJECTIVE: this study compares the hemodynamic effects of intra-aortic balloon pumping (IABP), left ventricular assist device (LVAD), and extracorporeal membrane oxygenation (ECMO) in left ventricular failure in pigs. METHODS: In 29 pigs weighing 12 +/- 0.7 kg left ventricular failure was induced by ligating the left anterior descending coronary artery. Eight animals served as controls. Eight pigs were treated by IABP, seven by LVAD, and six by ECMO. The study period lasted four hours. Hemodynamic and oxygen transport/uptake parameters were measured continuously or intermittently. RESULTS: Six animals of the ECMO and LVAD groups survived the 4 hour period, but only 3 and 4 animals of the IABP and control groups survived (p less than 0.05). Cardiac index decreased about 48% and 22% in the control and IABP groups (p less than 0.05), whereas there was only a slight decrease in the ECMO (9%) and LVAD (14%) groups. Oxygen delivery fell significantly in the control and IABP groups (p less than 0.05), compared with only a slight change in the LVAD and ECMO groups. CONCLUSION: ECMO is the most effective system for temporary circulatory support in severe ventricular failure. LVAD maintains cardiac output when pulmonary blood flow is provided. IABP is less efficient in supporting the failing heart, especially in the presence of severe ventricular arrhythmias.     

The innervated left ventricle: a mathematical model of function

A model of the innervated left ventricle is developed that characterises the left ventricle as a time-varying elastance (P/V) element which is a function of both end-diastolic volume and frequency of stimulation of the left stellate ganglion. This model is an extension of a denervated model developed earlier and accurately simulates the ventricular responses to various preload and afterload conditions at a given ionotropic state.     

Synchrony relationships between the left ventricle and a left ventricular assist device: an experimental study in pigs

Background: Synchronization between the left ventricle and a left ventricular assist device (LVAD) may be important for ventricular unloading and coronary perfusion. We assessed the synchrony between cardiac and LVAD cycles by increasing delays in steps of 100 msec throughout the cycle, under conditions of total and partial left ventricular support. Methods: We studied 7 healthy minipigs weighing 30-40 kg. A 60-cc Berlin Heart Excor LVAD was implanted and connected to a BCM 1200 console, making it possible to synchronize the LVAD systole and the EKG signal with a prefixed delay. We recorded hemodynamic parameters (including aortic, pulmonary, and left ventricular pressure) and LVAD flow for each delay. Results: Intraventricular pressure during LVAD systole was minimized with delays of around 40-80% of one cycle. In addition, total flow was higher under these conditions. Conclusions: This study shows that the synchronous mode of LVAD operation is feasible. Moreover, a delay in device contraction until the second half of the cardiac cycle optimizes ventricular unloading and may eventually improve myocardial recovery.     

Boundary detection and volume determination of the left ventricle from a cineangiogram

This paper is concerned with a method to detect left ventricular boundaries and the subsequent volume computation from a cineangiogram by a digital computer. It will first describe three digital techniques: (1) to restore the original dimensions by a logarithmic transformation; (2) to reduce noise by averaging images; and (3) to subtract images after and before dye injection, and then a boundary detection method based on statistical principles and heuristics. A method to locate the aortic valve will also be described.Experimental results on several cine frames will be presented to demonstrate the feasibility of these techniques. Once the boundary of the ventricle is determined, the computation of the volume is performed by the usual Simpson's rule.     

第三脑室三维断层影像解剖学及其临床意义

目的：为第三脑室区域临床影像学诊断和肿瘤的外科手术提供解剖学资料。方法：在１５具成人尸体头部的固定标本上，采用ＭＪ—３４６Ｂ型电动带锯每隔０．５ｃｍ作第三脑室横断、冠断和矢状断连续切片，观测了第三脑室的形态、大小、位置、毗邻关系和手术入路的径线值等。结果：第三脑室横径为１．９±２．７ｍｍ，上下径即穹窿体下缘中点至下丘脑沟中点间距为１４．１±２．７ｍｍ，前后径即室间孔至中脑水管上口间距为２３．９±２．７ｍｍ，其外侧壁的表面积为２７６～６７７ｍｍ２；松果体位于四叠体池内，长×宽×高约为７ｍｍ×７ｍｍ×３ｍｍ，略偏向左侧。结论：第三脑室前部入路优于后部入路，丘脑所占第三脑室侧壁面积大于下丘脑，下丘脑沟以上术中操作相对安全；第三脑室在三维断面上均能良好显示     

左室假腱索的解剖学研究及其临床意义

目的　为临床提供有关左室假腱索的解剖学基础。方法　采用 44例成人心脏标本 ,观察左室假腱索的出现率、附着点和形态 ,并对其长度和直径进行测量。结果　 44例心脏中 33例 (75 % )出现左室假腱索共 75条 ,平均每例 2 .2 7± 1 .38条。左室假腱索多附着于室间隔和后乳头肌、乳头肌和游离室壁之间。左室假腱索的长度和直径分别为 1 4 .62± 7.2 9mm和 0 .69± 0 .64mm。结论　左室假腱索是心内正常解剖结构 ,了解其形态特征 ,有助于临床的诊断     

In vivo effects on human neutrophils by administration of rhG-CSF and clinical significance]

To evaluate the clinical effect by administration of recombinant human granulocyte-stimulating factor (rhG-CSF) post chemotherapy in non-Hodgkin malignant lymphoma (NHL), 17 patients with NHL were subjected to this study. Administration of rhG-CSF ameliorated the decrease in absolute neutrophil counts after the cytotoxic chemotherapies and activated neutrophil functions in active oxygen product and expressions of adhesion proteins. To consistent with these results, rhG-CSF administrations post cytotoxic chemotherapy were effective for reducing infection complications associated with neutropenia. Furthermore, administration of rhG-CSF increased peripheral hematopoietic progenitor cells, thus suggesting promising therapeutic potential for autografting. Recently, it has been reported that blood neutrophils may synthesize mRNA and proteins important in inflammation including various cytokines such as IL-1, IL-6, TNF-alpha and IFN-alpha, but, administration of rhG-CSF showed no obvious effect on the level of either IL-1, IL-6, TNF-alpha or IFN-alpha in sera, and furthermore, the in vitro stimulation by rhG-CSF induced no significant production of these cytokines and expressions of TNF-alpha and IFN-alpha mRNAs. Finally, we studied on anti-tumor effect of administration of rhG-CSF in CDF1 mice inoculated with syngeneic lymphoma cells. rhG-CSF infusion suppressed the liver metastasis and prolonged the overall survival, thus suggesting the hypothesis that use of rhG-CSF in some patients with NHL might control the disease through stimulating both production and functional activation of neutrophils.