离体工作心脏模型与心脏解剖功能可视化研究

离体工作心脏模型在心血管相关学科的发展中起着重要作用,是医学研究和临床应用极为重要的技术平台。本文就离体工作心脏模型的建立和发展过程、建模原理以及心脏可视化研究的应用及发展前景进行综述。     

硝苯地平用于非循环系统疾病的治疗

硝苯地平（Nifedipine．NF）是钙通道阻滞剂，其选择性地阻滞钙离子通道，具有抑制全身各个器官平滑肌的兴奋性，减轻平滑肌收缩的作用。主要用于治疗心血管系统疾病。根据硝苯地平松弛平滑肌作用．临床上发现它在非循环系统的作用在不断增加，现就其非循环系统的作用概述如下。     

交感神经传出冲动对心血管系统调节的模型研究

目的建立交感神经传出冲动的计算机仿真模型,评价它对心血管系统的调节作用。方法利用包含多种心血管反射的血流动力学模型,运用动态仿真工具Simulink进行数学建模,采用ODE45可变步长算法模拟交感神经传出冲动。结果当缺氧或PCO2升高时,心脏交感神经的传出冲动均增大,PCO2升高时对阻力血管交感神经传出冲动的增快作用,远大于缺氧的作用。结论仿真模型构造清晰,具有可扩充性,可以作为动物实验的预研手段。     

心血管腔内超声显像

心血管腔内超声显像(Intravascular and Intracardiac Uitrasound Imaging; IUI)是将超声探头安置于导管顶端或导管样探头经动脉或静脉入循环系统,在所需观察区域显示心血管结构的新技术。它可定性。定量分析管壁斑块,鉴别管内血栓及管壁夹层,选择介入治疗方案,监视介入治疗过程及评价其疗     

骨种植体复合体有限元建模软件的编制

背景:有限元法在口腔医学领域得到了广泛应用,但建模方法及模型千差万别,缺乏标准.目前在国内外文献中尚未见到专门用于口腔种植预域的生物力学分析软件.目的:编制骨种植体复合体有限元建模软件.方法:在个人电脑上,通过计算机辅助设计软件所支持的Visual Basic for Application编程语言,编制能够自动生成骨种植体复合体计算机辅助设计模型的软件,并利用其有限元软件、数据库和电子表格软件接口,编制包含有限元建模、数据库和装配功能的骨种植体复合体自动建模软件.结果与结论:所编制的软件能够满足设计要求,完成各种类型骨种植体有限元模型的建立.结果提示通过AutoDesk Mechanical Desktop 2009DX、ANSYS Workbench 10.1和Visual Basic for Application语言相结合的方法,可以编制出快速、自动生成骨种植体有限元模型的软件包.     

危重心血管病患者行机械辅助通气的护理

危重心血管患者虽然病情重，但大多仍神志清醒，应用机械辅助通气前须做好心理护理，使其情绪保持稳定，防止自行拔除气管插管；还要密切观察机械通气对循环系统造成的影响。现将本院CCU32例危重心血管患者施行机械辅助通气的护理体会介绍如下。     

瞬时波强技术评价原发性高血压患者血流动力学变化

瞬时波强(wave intensity,WI)是一项研究心血管系统血流动力学及心脏与血管相互关系的新技术,其定义为循环系统的任意位置的压力变化(dP/dt)与速度变化(dV/dt)的乘积,即WI=(dP/dt)×(dV/dt).本研究旨在探讨WI技术评价原发性高血压患者血流动力学变化的临床应用价值.     

第十讲 神经功能性心脏病

神经功能性心脏病,也称心血管神经官能症。它是全身神经官能症的一种,其临床表现以循环系统为主,以青、中年多见,女性患者居多,无器质性病变,预后一般良好;但处理不当也可引起医源性疾病,造成病人部分丧失或完全丧失工作能力。     

老年患者开胸手术后心血管并发症的护理

老年患者开胸手术后心血管并发症的护理第一军医大学南方医院（广州５１０５１５）杨丽朱志红开胸手术的创伤和麻醉对呼吸和循环系统影响较大，尤其是老年病人表现更明显，故手术后更易发生心血管并发症。手术后病情的观察和得力的护理措施，是抢救病人成功必不可少的条件...     

慢性心力衰竭患者营养不良风险预测模型的构建及验证

目的 构建慢性心力衰竭患者营养不良风险预测模型,并验证该模型的预测效果.方法 2019年1月-2020年1月,选择镇江市某三级甲等医院心血管内科住院的109例患者作为模型建立对象,将其分为营养不良组(40例)和营养正常组(69例).采用Logistic回归建立慢性心力衰竭患者营养不良风险预测模型,采用Hosmer-Le...     

The cardiovascular system as coupled oscillators?

Based on physiological knowledge, and on an analysis of signals related to its dynamics, we propose a model of the cardiovascular system. It consists of coupled oscillators. Each of them describes one of the subsystems involved in the regulation of one passage of blood through the circulatory system. The flow of blood through the system of closed tubes-the blood vessels-is described by wave equations.     

Physiology of continuous-flow pumps

The use of mechanical pumps for circulatory support started in the mid-1950s. The evolution of these devices has led to the present-day use of continuous-flow pumps to take over the function of a patient's failing heart. The physiology associated with rotary blood pump use is quite different from normal cardiovascular physiology. Clinicians caring for patients who are supported by rotary blood pumps must have an understanding of the differences in physiology, monitoring methods, and unique complications associated with the use of these pumps.     

Sauna bather's circulation

Cutaneous circulation increases greatly in sauna in order to prevent body heating. Blood pressure tends to fall but this is prevented by increased cardiac output by means of faster heart rate and by decreased blood flow to the visceral organs. Cooling in cold air, shower, water or rolling in snow causes rapid cutaneous vasoconstriction, which leads to elevation of arterial blood pressure and increase of central venous blood volume. The effects of both heat and cold are mediated via the sympathetic nervous system. The circulatory responses to sauna are related to the intensity and duration of the heat exposure. An ordinary sauna bath increases cardiac workload about as much as moderate or vigorous walking. Habituation to sauna decreases the sympathetic stimulation and cardiovascular responses. Sudden cooling, for example diving in cold water, causes a severe transitory volume load and pressure load to the heart and increases the possibility of cardiac arrhythmias. The risk of cardiovascular complications in correctly practiced sauna bathing is very small and it is confined to subjects predisposed to the risk because of manifest or latent cardiovascular abnormalities.     

Blood flow to organs: parameters for function and survival in critical illness

Tissues are usually considered as being supply-dependent (e.g., heart and brain) and supply-independent (e.g., splanchnic area, kidneys, skin, and resting muscle) for oxygen delivery. When cardiovascular function is compromised, circulatory compensations are aimed at maintaining supply-dependent tissues. In the long term, this leads to the possibility of an inadequate blood flow to supply independent tissues. The perfusion maintenance of all organs requires adequate cardiac output, blood volume, and arterial BP. When BP and cardiac output fail, regional perfusion diminishes. Although the human system tolerates anemia well, optimum Hct levels are probably between 30% to 40%. Inadequate perfusion can be supplemented partially by increasing the FIO2 on a temporary basis. Hyperoxic arterial oxygen tensions may cause maldistribution of blood flow within organs.     

Cardiovascular simulation using a multiple modeling method on a digital computer—Simulation of interaction between the cardiovascular system and angiotensin II

A cardiovascular system model that simulates interactive responses to drugs has been developed on a small digital computer. The overall model basically consists of three models. The first is a momentum transport model that represents relations between blood pressure and flow in the cardiovascular system. In this model, the cardiovascular system is divided into 14 components and modeled by using equivalent electrical circuits. The second is a mass transport model comprising 14 compartments corresponding to the respective components of the cardiovascular system. This model represents the distribution of the administered drug in the various cardiovascular components. The third is an interaction model that represents the relationships between the momentum and mass transport models. This model causes variations in the resistance and capacitance parameters of the momentum transport model as a function of the current drug concentrations in the appropriate compartments of the mass transport model. The capacitances representing the ventricles are varied in a time-dependent fashion to simulate the beat of the heart. Simulation is performed by using the Euler method to solve a system of 28 ordinary differential equations governing the momentum and mass transport models on a 32-bit microcomputer, a Macintosh II. The model was assessed by performing two demonstrations of the cardiovascular response to the vasopressor angiotensin II (AT II). They first examined the interaction between the cardiovascular system and AT II. The effect of AT II on the cardiovascular system was incorporated into the interaction model. Administration of AT II as a constant infusion (200 µg/hr) resulted in an elevation of mean arterial pressure from approximately 100 to 150 mm Hg. The second was a pharmacodynamic demonstration of the cardiovascular system in the presence of tumor tissue during induced-hypertension chemotherapy. A tumor tissue component was added to the cardiovascular system model, thereby incorporating into the interaction model the effects of blood pressure elevation on tumor tissue. The same administration of AT II as above resulted in an increase in blood flow from 0.3 and 1.3 ml/s (i.e., an increase of approximately 460%) in the carcinomatous tissue. The results, along with those obtained earlier with sodium nitroprusside, indicate that the present simulator could represent the cardiovascular system during administration of vasoactive drugs.     

Ketamine-diazepam N2O combination anesthesia—a new “circulatory-system-sparing” type of anesthetic in experimental surgery

For studying the hemodynamics of the greater and lesser circulatory system in animals, the impact of general anesthesia upon cardiovascular functions should be as small, as possible. The marked circulation-depressing effect of halothane, which has so far been given preference for experiments on large animals, was confirmed by the present study of the miniature pig. There was a significant decrease in MAP, cardiac index and dp/dt_max/IP, and an increase in PAP_p. Useful insights into hemodynamics, derived from experiments modeling the heart, lungs or vascular system cannot be gained for a cardiovascular system, the functions of which are greatly altered by such an anesthesia. As a new form of anesthesia with minimal cardiovascular influence, the ketamine-diazepam N₂O combination, which has already been successfully applied in operations on the open human heart, is introduced into experimental surgery.     

影像技术评价胎儿心功能的研究进展

由于胎儿时期具有特殊的心脏结构,胎儿的心功能往往与胎儿宫内生长发育情况息息相关.胎儿肺循环阻力较高且体内只有动静脉混合血,心脏是控制胎儿全身血流的关键,在其他系统出现异常之前,心功能往往早已出现微妙的变化.因此,胎儿心功能可一定程度反映胎儿在宫内缺血、缺氧等情况.准确评估胎儿心功能,可以尽早发现不同疾病状态下胎儿心血管...     

The vasovagal response.

The vasovagal response is the development of inappropriate cardiac slowing and arteriolar dilatation. Vasovagal responses reflect autonomic neural changes: bradycardia results from sudden augmentation of efferent vagal activity, and hypotension results from sudden reduction or cessation of sympathetic activity and relaxation of arterial resistance vessels. Two different neural pathways are thought to be involved, one originating in the hypothalamus, the other in the heart. Direct hypothalamic activation of the medullary cardiovascular centres triggered by emotional stress or pain causes a vasovagal response (central type). The combination of a reduced central blood volume secondary to venous pooling or blood loss, and an increased inotropic state of the heart, may stimulate ventricular mechanoreceptors and provoke vasodilatation and bradycardia (peripheral type). Cardiovascular afferents originating from stretch receptors in various parts of the vascular tree sometimes induce opposite reflexes when compared with those from ventricular afferents. The depressor reflex involved in the peripheral type of vasovagal response originates in the heart itself and overrides normal baroreflex circulatory control; an antagonism between the control of volume and pressure on the filling side of the heart and the control system of arterial pressure becomes apparent. Vasovagal responses are not necessarily abnormal; the neural pathways involved in the vasovagal response are probably present in all healthy subjects who individually mainly differ in susceptibility.     

The role of the autonomic nervous system in hypertension: a bond graph model study

A bond graph model of the cardiovascular system with embedded autonomic nervous regulation was developed for a better understanding of the role of the autonomic nervous system (ANS) in hypertension. The model is described by a pump model of the heart and a detailed representation of the head and neck, pulmonary, coronary, abdomen and extremity circulation. It responds to sympathetic and parasympathetic activities by modifying systemic peripheral vascular resistance, heart rate, ventricular end-systolic elastance and venous unstressed volumes. The impairment of ANS is represented by an elevation of the baroreflex set point. The simulation results show that, compared with normotensive, in hypertension the systolic and diastolic blood pressure (SBP/DBP) rose from 112/77 mmHg to 144/94 mmHg and the left ventricular wall thickness (LVWT) increased from 10 mm to 12.74 mm. In the case that ANS regulation was absent, both the SBP and DBP further increased by 8 mmHg and the LVWT increased to 13.22 mm. The results also demonstrate that when ANS regulation is not severely damaged, e.g. the baroreflex set point is 97 mmHg, it still has an effect in preventing the rapid rise of blood pressure in hypertension; however, with the worsening of ANS regulation, its protective role weakens. The results agree with human physiological and pathological features in hemodynamic parameters and carotid baroreflex function curves, and indicate the role of ANS in blood pressure regulation and heart protection. In conclusion, the present model may provide a valid approach to study the pathophysiological conditions of the cardiovascular system and the mechanism of ANS regulation.     

Effect of acute anemia on blood oxygen-transporting function during postsurgical period

The retrospective study was undertaken to examine the impact of anemia developing during abdominal operations on oxygen transport and consumption. The concomitance of anemia and low reserves of the blood circulatory system was shown to be accompanied by obvious cardiovascular system tension. This appeared as the greater magnitude of tachycardia, metabolic disorders and is attended by high oxygen extraction. The paper shows it necessary to decide whether hemotransfusion should be made, by taking into account the compensatory capacities of the cardiovascular system, and not just hemoglobin levels.