DIASTOLIC MECHANICS OF THE LEFT VENTRICLE AND LEFT ATRIU

左心室和左心房的舒张力学

• 批准号: 3474092
• 负责人: SERJAN D NIKOLIC
• 金额: $ 8.26万
• 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/3474092
• 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 阐明具体的被动和主动的定量贡献 左心房（LA）和左心室（LV）对指数的特性 心脏舒张功能。 这些信息将建立一个生理和 临床数据解释的生物物理学基础。 我们建议 研究麻醉开胸犬的实验方法， 本实验室：1）LV收缩期容量钳夹; 2）LV舒张期容量 夹持; 3）LA控制填充。 第一个和第二个是 通过定制设计的计算机控制的主动脉夹完成， 能够控制开始和停止的人工二尖瓣 心室射血和充盈，从而在不同的位置夹住LV 卷 第三种是通过控制肺静脉血流来实现的， 计算机控制的肺静脉钳。 这些技术结合起来 通过测量流量（超声波和电磁波）、压力 （微压计）、LV尺寸（超声）、LV容量（电导 导管），并与超声心动图和多普勒速度测量， 能够提供关于 以及充填的动力学。 我们将量化 正常生理变化期间LV和LA参数的变化， 以及在急性干预期间：心肌顿抑和局部缺血， 房颤、二尖瓣狭窄和二尖瓣返流。 LV和 将重点描述LA被动压力-容积关系， 平衡体积，基于我们新描述的体积参数 舒张压-容积关系的一部分。 我们将描述 LV和LA的以下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 性质、LV舒张和二尖瓣装置在 确定LV室性质; 2. LA储液器、导管和泵 功能协调发展的 数据将用于解决以下具体问题 问题：变力状态、心率或后负荷是否影响LV 舒张期弹性恢复力和粘性力？ 是收缩功能 舒张末期容积（纤维长度）和 填充过程（纤维延长）？ 后负荷的作用是什么 增加对LV的舒张和充盈;弹力作用是什么 在产生局部压力时的反作用力和舒张期LV形状 心室内的差异？ 左心室的舒张特性是什么 受二尖瓣结构的影响 收缩末期和 舒张末期P-V关系标准化，以解释心脏差异 尺寸？ 急性心肌缺血和顿抑对LV有什么影响 弹性反冲、粘性和松弛？ 如何做HR，LA卷 左室充盈时左室顺应性是否影响左室功能？ 有哪些 房颤期间不同LA功能的贡献， 二尖瓣返流和二尖瓣狭窄 我们亦会把 生理学研究的结果转化为计算模型， 综合分析了材料力学性能之间的关系 左心室和左心房的舒张期充盈特征。