LEFT VENTRICULAR-ARTERIAL COUPLING

心血管系统的性能取决于以下因素的相互作用： 其组成部分。 我们建议研究左的耦合 心室（LV）和动脉系统在清醒的动物与完整 休息时、运动期间以及LV性能下降时的反射。的 分析LV和动脉压（P）-容量（V）关系，用于 这些研究是基于先前对孤立性左心室射血的观察， 动脉系统的模型。 这些概念并没有被 在完整、清醒动物的循环中进行评价， 运动和临床上重要的疾病过程还没有被 以前调查过。 以下具体假设将 评估。 假设1：每搏输出量（SV）和LV收缩末期 P（PES）在生理相关范围内呈线性相关。 的 该关系的斜率EA是动脉的有效弹性 在大多数情况下，主要由心脏决定 速率和总外周血管阻力。 假设2：LV卒中 当LV的收缩末期弹性（EES）等于EA时，功最大， 而机械效率（动脉卒中功与总功的比率 当EES大于EA时，压力-体积面积（SW/PVA）最大。 假设3：正常心血管系统在EES静息状态下运行 略大于EA，介于最大SW和 机械效率。 假设4：在运动过程中，LV和动脉 系统功能更接近最大机械效率点， EES > EA;静息时起搏引起的心率增加相似 在EES < EA的次优匹配中，假设5和6：当LV 快速起搏引起的心力衰竭或冠状动脉 闭塞，LV和动脉系统的耦合不是最佳的，因为EA > EES，但可以通过使用以下方法减少EA返回到最佳状态： 血管扩张剂 假设1将在麻醉开胸的情况下进行评估， 每搏输出量可通过右心室精确控制的准备 清醒狗的心脏搭桥术 其他假设将通过以下方式进行评估： 研究先前用仪器测量LV压力的清醒狗， 音量. EES将被确定为LV收缩末期的斜率 通过瞬时腔静脉改变LV P和V产生的压力-容积关系 闭塞。 EA将被确定为PES/SV。 这些研究将提供重要的新信息耦合的 反射完好的清醒动物的LV和动脉系统 休息、运动期间和LV性能下降后。这些 研究可能会导致合理的干预措施，以改善泵的功能， 常见心血管疾病患者。

The performance of the cardiovascular system depends on the interaction of its components. We propose to investigate the coupling of the left ventricle (LV) and arterial systems in conscious animals with intact reflexes at rest, during exercise, and with depressed LV performance. The analysis of LV and arterial pressure (P)-volume (V) relations to be used in these studies is based on previous observations in the isolated LV ejecting into a model of the arterial system. These concepts have not been evaluated in the circulation of intact, conscious animals and the effects of exercise and clinically important disease processes have not been previously investigated. The following specific hypotheses will be evaluated. Hypothesis 1: The stroke volume (SV) and the LV end-systolic P (PES) are linearly related over the physiologically relevant range. The slope of this relation, EA, is the effective elastance of the arterial system, and is primarily determined under most circumstances by the heart rate and total peripheral vascular resistance. Hypothesis 2: LV stroke work is maximal when end-systolic elastance of the LV (EES) is equal to EA, while mechanical efficiency (the ratio of arterial stroke work to total pressure-volume area, SW/PVA) is maximum when EES is greater than EA. Hypothesis 3: The normal cardiovascular system operates at rest with EES slightly greater than EA, intermediate between points for maximum SW and mechanical efficiency. Hypothesis 4: During exercise, the LV and arterial system function closer to the point of maximum mechanical efficiency with EES > EA; similar increases in heart rate produced by pacing at rest result in suboptimal matching with EES < EA, Hypotheses 5 and 6: When LV function is depressed by rapid pacing induced heart failure or coronary occlusion, the coupling of the LV and arterial system is not optimal, as EA > EES, but can be returned toward optimal by decreasing EA using vasodilators. Hypothesis 1 will be evaluated both in an anesthetized, open-chest preparation in which stroke volume can be precisely controlled by right heart bypass in conscious dogs. The other hypotheses will be evaluated by studying conscious dogs previously instrumented to measure LV pressure and volume. EES will be determined as the slope of the LV end- systolic pressure-volume relation produced by varying LV P and V by transient caval occlusions. EA will be determined as PES/SV. These studies will supply important new information on the coupling of the LV and arterial system of the conscious animal with intact reflexes at rest, during exercise, and following depression of LV performance. These studies may lead to rational interventions to improve pump function in patients with common cardiovascular diseases.