DIASTOLIC MECHANICS OF THE LEFT VENTRICLE AND LEFT ATRIU

左心室和左心房的舒张力学

• 批准号: 3474093
• 负责人: SERJAN D NIKOLIC
• 金额: $ 8.31万
• 依托单位: PALO ALTO MEDICAL FOUNDATION RES INST
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-30 至 1996-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3474093
• 关键词: atrial fibrillation; atrium; biomechanics; computer simulation; dogs; echocardiography; elasticity; electronic pacemaker; heart contraction; heart dimension /size; heart function; heart rate; heart ventricle; intracardiac pressure; intracardiac volume; mitral valve; mitral valve insufficiency; mitral valve stenosis; myocardial ischemia /hypoxia; ultrasound blood flow measurement

The long range objective of the studies proposed in this application is to elucidate the quantitative contributions of the specific passive and active properties of both left atrium (LA) and left ventricle (LV) to the indices of diastolic function. This information will establish a physiological and biophysical basis for the interpretation of clinical data. We propose to study anesthetized open-chest dogs with the experimental methods unique to this laboratory: 1) LV systolic volume clamping; 2) LV diastolic volume clamping; and 3) LA controlled filling. The first and second are accomplished by a custom designed computer controlled aortic clamp and prosthetic mitral valve capable of controlling the onset and the cessation of ventricular ejection and filling, thus clamping the LV at different volumes. The third is achieved by controlling pulmonary venous flow with a computer controlled pulmonary venous clamp. These techniques, combined with the measurements of flow (ultrasonic and electromagnetic), pressure (micromanometer), LV dimensions (ultrasonic , LV volume (conductance catheter), and with echocardiographic and Doppler velocity measurements, are capable of providing new and important information regarding the mechanics of diastole and the dynamics of filling. We will quantify the changes in the LV and LA parameters during normal physiological variations, as well as during acute interventions: myocardial stunning and ischemia, atrial fibrillation, mitral stenosis and mitral regurgitation. The LV and LA passive pressure-volume relationships will be described with emphasis on the equilibrium volume, the volume parameter based on our new description of the diastolic pressure-volume relation. We will characterize the following specific mechanical and functional properties of the LV and LA:1. passive elastic (tensile and compressive), viscoelastic and geometrical LV properties, LV relaxation and the role of the mitral valve apparatus in determining LV chamber properties; 2. LA reservoir, conduit and pump functions. Data will be utilized to address the following specific questions: Does inotropic state, heart rate or afterload influence LV diastolic elastic restoring and viscous forces? Is systolic function influenced independently by both end-diastolic volume (fiber length) and process of filling (fiber lengthening)? What is the effect of afterload increase on the LV relaxation and filling; What is the role of elastic recoil forces and diastolic LV shape in creating regional pressure differences within the ventricle? What diastolic properties of the LV are influenced by the mitral valve apparatus? How are the end-systolic and end-diastolic P-V relations normalized to account for difference in heart size? What is the effect of acute myocardial ischemia and stunning on LV elastic recoil, viscous properties and relaxation? How do HR, LA volume and LA compliance affect LA function during LV filling? What are the contributions of different LA functions during atrial fibrillation, in mitral regurgitation and mitral stenosis? We will also incorporate the findings of the physiological studies into a computational model to provide a comprehensive analysis of the relations between the mechanical properties of the LV and LA, and the characteristics of diastolic filling.

本申请中提出的研究的长期目标是 阐明特定的被动和主动的数量贡献 左心房(LA)和左心室(LV)对各指标的影响 心脏的舒张期功能。这一信息将建立一个生理和 临床数据解释的生物物理基础。我们建议 用独特的实验方法研究麻醉开胸犬 本实验室：1)左心室收缩期容量钳制；2)左心室舒张期容量 夹持；3)LA控制充填。第一个和第二个是 由定制设计的计算机控制的主动脉夹和 可控制起搏和止血的人工二尖瓣 心脏的射血和充盈，从而使左心室夹在不同的位置 音量。第三种是通过控制肺静脉流量实现的 一种计算机控制的肺静脉夹。这些技术结合在一起， 通过测量流量(超声波和电磁)、压力 (微压计)、LV尺寸(超声波、LV体积(电导 导管)，并通过超声心动图和多普勒速度测量， 能够提供有关 舒张力学和充盈动力学。我们将量化 在正常生理变化过程中LV和LA参数的变化， 以及在急性干预期间：心肌顿抑和缺血， 房颤、二尖瓣狭窄和二尖瓣返流。LV和 被动压力-体积关系的描述将重点放在 平衡体积，基于我们新描述的体积参数 舒张压-容量关系。我们将描述 以下是LV和LA的特定机械和功能特性：1. 被动弹性(拉伸和压缩)、粘弹性和几何LV 二尖瓣装置的特性、左室舒张功能及在二尖瓣病变中的作用 确定LV室性能；2.La储液器、导管和泵 功能。数据将用于解决以下特定问题 问题：肌力状态、心率或后负荷是否会影响LV 舒张期弹性恢复和粘性力？是收缩功能吗？ 独立地受舒张末容量(纤维长度)和 灌装过程(纤维加长)？后负荷的影响是什么？ 增加对LV的松弛和充盈；弹性的作用是什么 后坐力和舒张期左心室形态在创造区域压力中的作用 脑室内的差异？左心室的舒张期特性是什么 受二尖瓣装置的影响？心脏收缩末期和舒张期 正常的舒张末P-V关系以解释心脏的差异 尺码？急性心肌缺血和顿抑对左心功能的影响 弹性后坐、粘性和松弛？HR、LA数量如何 左心充盈时左房顺应性是否影响左房功能？什么是 不同左房功能在心房颤动中的作用 二尖瓣返流和二尖瓣狭窄？我们还将合并 将生理学研究的结果转化为计算模型以提供 力学性能之间关系的综合分析 LV和LA的变化以及舒张期充盈的特点。