Korn Leonie, Rüschen Daniel, Zander Niklas, Leonhardt Steffen, Walter Marian
Chair of Medical Information Technology, RWTH Aachen, Aachen, Germany.
Artif Organs. 2018 Feb;42(2):131-140. doi: 10.1111/aor.13000. Epub 2017 Oct 12.
Classically, mock circulatory loops only simulate mechanical properties of the circulation. To connect the hydraulic world with electrophysiology, we present a real-time electrical activity model of the heart and show how to integrate this model into a real-time mock loop simulation. The model incorporates a predefined conduction pathway and a simplified volume conductor to solve the bidomain equations and the forward problem of electrocardiography, resulting in a physiological simulation of the electrocardiogram (ECG) at arbitrary electrode positions. A complete physiological simulation of the heart's excitation would be too CPU intensive. Thus, in our model, complexity was reduced to allow real-time simulation of ECG-triggered medical systems in vitro; this decreases time and cost in the development process. Conversely, the presented model can still be adapted to various pathologies by locally changing the properties of the heart's conduction pathway. To simulate the ECG, the heart is divided into suitable areas, which are innervated by the hierarchically structured conduction system. To distinguish different cardiac regions, a segmentation of the heart was performed. In these regions, Prim's algorithm was applied to identify the directed minimal spanning trees for conduction orientation. Each node of the tree was assigned to a cardiac action potential generated by its hybrid automaton to represent the heart's conduction system by the spatial distribution of action potentials. To generate the ECG output, the bidomain equations were implemented and a simple model of the volume conductor of the body was used to solve the forward problem of electrocardiography. As a result, the model simulates potentials at arbitrary electrode positions in real-time. To verify the developed real-time ECG model, measurements were made within a hybrid mock circulatory loop, including a simple ECG-triggered ventricular assist device control. The model's potential value is to simulate physiological and pathological behavior for hardware-in-the-loop testing of medical devices in an ECG-triggered scenario.
传统上，模拟循环回路仅模拟循环系统的力学特性。为了将流体力学领域与电生理学联系起来，我们提出了一种心脏实时电活动模型，并展示了如何将该模型集成到实时模拟循环回路中。该模型包含一个预定义的传导通路和一个简化的容积导体，用于求解双域方程和心电图的正向问题，从而在任意电极位置实现心电图（ECG）的生理模拟。对心脏兴奋进行完整的生理模拟会消耗过多的中央处理器资源。因此，在我们的模型中，通过简化复杂性以实现对体外心电图触发的医疗系统进行实时模拟；这减少了开发过程中的时间和成本。相反，所提出的模型仍可通过局部改变心脏传导通路的特性来适应各种病理情况。为了模拟心电图，心脏被划分为合适的区域，这些区域由分层结构的传导系统支配。为了区分不同的心脏区域，对心脏进行了分割。在这些区域中，应用普里姆算法来识别用于传导方向的有向最小生成树。树的每个节点都被分配一个由其混合自动机生成的心脏动作电位，通过动作电位的空间分布来表示心脏的传导系统。为了生成心电图输出，实现了双域方程，并使用了一个简单的人体容积导体模型来解决心电图的正向问题。结果，该模型实时模拟任意电极位置的电位。为了验证所开发的实时心电图模型，在一个混合模拟循环回路中进行了测量，包括一个简单的心电图触发的心室辅助装置控制。该模型的潜在价值在于，在心电图触发的场景中，为医疗设备的硬件在环测试模拟生理和病理行为。
