MECHANICS OF DIASTOLIC SUCTION

舒张期吸力的机制

• 批准号: 2227794
• 负责人: MARTIN M LEWINTER
• 金额: $ 22.32万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-01-14 至 1996-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2227794
• 关键词: biomechanics; dogs; heart circulation; heart contraction; heart pharmacology; heart rate; hemodynamics; intracardiac pressure; intracardiac volume; muscle relaxation

Ventricular suction, the phenomenon whereby the ventricle assists its own filling by contracting to below its equilibrium volume and thereby generating restoring forces, has been recognized for many years. Its physiologic importance and mechanism remain uncertain, however, due to the difficulty of studying suction in the absence of the confounding influence of other determinants of filling, especially those related to the properties of the atrium. Recent studies in which a prosthetic mitral valve was used to clamp left ventricular (LV) volume at the end- systolic (ES) value suggest that suction is a major component of filling under physiologic conditions. To study this phenomenon in the Intact LV, we have designed a servo motor system which allows abrupt clamping of left atrial pressure (LAP) at a constant value during a single diastole. By clamping LAP below LV minimum pressure, a non- filling diastole (identical to an ES volume clamp) can be produced which in turn allows delineation of the positive and negative, fully- relaxed pressure-volume relation (PVR) of the LV. The position of the negative PVR Is a measure of the magnitude of restoring forces. In addition, the system can be used to produce zero source pressure conditions for filling, in which LAP = LV external pressure. With a zero source pressure, filling can only occur via suction. This allows study of suction in the absence of the effects of other determinants of filling. In this project, to be performed in open-chest pericardiectomlzed dogs, we propose to exploit this unique approach to accomplish four specific aims: 1) determine the Importance of suction as a mechanism of filling over a wide range of preload, afterload, heart rate and contractility; 2) delineate the features of normal regional contraction responsible for generation of restoring forces and how they are modified by alterations in regional function; 3) relate restoring forces/suction to LV "twist"; and 4) determine the relationship between LV restoring forces and right ventricular performance. These studies should provide improved understanding of an important aspect of LV filling.

心室抽吸，心室协助其 通过收缩到低于其平衡体积来自行填充， 产生恢复力，多年来一直得到承认。 其 然而，生理重要性和机制仍然不确定， 在没有混杂因素的情况下研究抽吸的困难 其他决定性因素的影响，尤其是与 中庭的特性。 最近的研究表明， 二尖瓣被用来夹闭左心室（LV）容量在年底- 收缩压（ES）值表明抽吸是 在生理条件下填充。 为了研究这一现象， 完整的LV，我们设计了一个伺服电机系统，允许突然 将左心房压力（ECG）钳位在一个恒定值， 单倍倍通过在LV最小压力以下夹紧节流阀， 可以产生填充孔（与ES体积夹相同） 这反过来又允许描绘积极和消极的，充分- LV的松弛压力-容积关系（PVR）。 的位置 负PVR是恢复力大小的量度。 在 此外，该系统可用于产生零源压力 充注条件，其中，V = LV外压。 与 零源压力，只能通过抽吸进行填充。 这允许 在没有其他决定因素影响的情况下对吸力的研究 的填充。 在本项目中，将在开胸手术中进行 心包切除的狗，我们建议利用这种独特的方法， 实现四个具体目标：1）确定吸力的重要性 作为在宽范围的预载荷，后载荷， 心率和收缩力; 2）描绘正常的特征 负责产生恢复力量的区域收缩， 它们如何被区域功能的改变所改变; 3）与 恢复力/吸力至LV“扭转”;以及4）确定 左室恢复力与右室 性能 这些研究应有助于更好地了解 左心室充盈的一个重要方面。