MECHANICS OF DIASTOLIC SUCTION

脑室抽吸，这是一种脑室协助其 通过收缩到低于其平衡体积来填充自己，从而 产生恢复力，已经被认识到很多年了。它的 然而，由于以下原因，生理重要性和机制仍不确定 在没有混淆的情况下研究吸力的难度 填充物的其他决定因素的影响，特别是相关因素 中庭的特性。最近的研究表明，假肢 术后用二尖瓣夹闭左室血容量。 收缩压(ES)值表明吸力是 生理条件下的充填。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 左房内压(LAP)在心脏停搏期间保持恒定值 单瓣舒张期。通过在LV最低压力下夹紧搭接，非 可生产充盈舒张素(等同于ES音量夹) 这反过来又可以充分地描绘出积极和消极的- 左心室的松弛压力-体积关系(PVR)。的位置。 负PVR是恢复力大小的量度。在……里面 此外，该系统还可用于产生零源压力 灌装条件，其中LAP=LV外部压力。使用一个 零源压力，灌装只能通过吸气进行。这使得 在没有其他决定因素影响的情况下的吸力研究 填饱肚子了。在这个项目中，将在开胸状态下进行 心包切除犬，我们建议利用这一独特的方法来 完成四个具体目标：1)确定吸力的重要性 作为一种填充大范围的预载、后载、 心率和收缩能力；2)勾画正常人的特征 区域收缩导致恢复力量的产生和 它们是如何因区域功能的变化而改变的；3)关系 将力/吸力恢复到LV“扭转”；以及4)确定 左心室恢复力与右室的关系 性能。这些研究应该提供更好的理解 LV充盈的一个重要方面。

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.