Fresiello Libera, Meyns Bart, Di Molfetta Arianna, Ferrari Gianfranco
Department of Clinical Cardiac Surgery, Katholieke Universiteit LeuvenLeuven, Belgium; Institute of Clinical Physiology, National Research CouncilRome, Italy.
Department of Clinical Cardiac Surgery, Katholieke Universiteit Leuven Leuven, Belgium.
Front Physiol. 2016 Jun 8;7:189. doi: 10.3389/fphys.2016.00189. eCollection 2016.
The physiological response to physical exercise is now recognized as an important tool which can aid the diagnosis and treatment of cardiovascular diseases. This is due to the fact that several mechanisms are needed to accommodate a higher cardiac output and a higher oxygen delivery to tissues. The aim of the present work is to provide a fully closed loop cardiorespiratory simulator reproducing the main physiological mechanisms which arise during aerobic exercise. The simulator also provides a representation of the impairments of these mechanisms in heart failure condition and their effect on limiting exercise capacity. The simulator consists of a cardiovascular model including the left and right heart, pulmonary and systemic circulations. This latter is split into exercising and non-exercising regions and is controlled by the baroreflex and metabolic mechanisms. In addition, the simulator includes a respiratory model reproducing the gas exchange in lungs and tissues, the ventilation control and the effects of its mechanics on the cardiovascular system. The simulator was tested and compared to the data in the literature at three different workloads whilst cycling (25, 49 and 73 watts). The results show that the simulator is able to reproduce the response to exercise in terms of: heart rate (from 67 to 134 bpm), cardiac output (from 5.3 to 10.2 l/min), leg blood flow (from 0.7 to 3.0 l/min), peripheral resistance (from 0.9 to 0.5 mmHg/(cm(3)/s)), central arteriovenous oxygen difference (from 4.5 to 10.8 ml/dl) and ventilation (6.1-25.5 l/min). The simulator was further adapted to reproduce the main impairments observed in heart failure condition, such as reduced sensitivity of baroreflex and metabolic controls, lower perfusion to the exercising regions (from 0.6 to 1.4 l/min) and hyperventilation (from 9.2 to 40.2 l/min). The simulator we developed is a useful tool for the description of the basic physiological mechanisms operating during exercise. It can reproduce how these mechanisms interact and how their impairments could limit exercise performance in heart failure condition. The simulator can thus be used in the future as a test bench for different therapeutic strategies aimed at improving exercise performance in cardiopathic subjects.
现在人们认识到，对体育锻炼的生理反应是一种重要工具，可辅助心血管疾病的诊断和治疗。这是因为需要多种机制来适应更高的心输出量以及向组织输送更多的氧气。本研究的目的是提供一个完全闭环的心肺模拟器，再现有氧运动过程中出现的主要生理机制。该模拟器还能呈现心力衰竭状态下这些机制的损伤情况及其对运动能力限制的影响。模拟器由一个心血管模型组成，包括左、右心脏以及肺循环和体循环。后者被分为运动区域和非运动区域，并由压力反射和代谢机制控制。此外，模拟器还包括一个呼吸模型，可再现肺部和组织中的气体交换、通气控制及其力学机制对心血管系统的影响。该模拟器在三种不同的骑行工作负荷（25、49和73瓦）下进行了测试，并与文献中的数据进行了比较。结果表明，模拟器能够在以下方面再现对运动的反应：心率（从67次/分钟到134次/分钟）、心输出量（从5.3升/分钟到10.2升/分钟）、腿部血流量（从0.7升/分钟到3.0升/分钟）、外周阻力（从0.9毫米汞柱/（立方厘米/秒）到0.5毫米汞柱/（立方厘米/秒））、中心动静脉氧差（从4.5毫升/分升降到10.8毫升/分升）和通气量（6.1 - 25.5升/分钟）。该模拟器进一步进行了调整，以再现心力衰竭状态下观察到的主要损伤情况，如压力反射和代谢控制的敏感性降低、运动区域的灌注减少（从0.6升/分钟到1.4升/分钟）以及过度通气（从9.2升/分钟到40.2升/分钟）。我们开发的模拟器是描述运动过程中基本生理机制的有用工具。它可以再现这些机制如何相互作用以及它们的损伤如何在心力衰竭状态下限制运动表现。因此，该模拟器未来可作为一个测试平台，用于评估旨在改善心脏病患者运动表现的不同治疗策略。
