近年心因性猝死是國人重要死亡因素之一，其中又以由心室顫動所導致之心因性猝死佔了多數。而心臟從正常的跳動到心室顫動之間的演進過程有其動力學之因素，且其動力學系統為一非線性系統。從心臟動力學的觀點認為，心室顫動是心臟的一種混沌且不協調之活動狀態。同時，心臟的動力學特性從正常演化至混沌間會經歷過倍週期分岔 (Bifurcation) 現象。故在倍週期發生後，我們可以在週期二之交替脈(period-2 alternans) 出現時進行控制進以抑制心室顫動的發生。為了解心臟動力學之變化，本研究使用了單細胞與一維纖維結構之 Shiferaw-Fox model(此為一心臟之鈣離子耦合模型) 以模擬心臟之動力學系統，同時引入了一非線性調控方式進行調控模擬。本研究發現這樣的週期二交替脈中可以分成不同階段，並且找到了在不同階段相應的控制方式。此外，研究中亦發現進行控制時能成功控制的臨界強度與心肌組織中被控制之細胞占纖維中之比例的倒數呈現線性關係。這些研究結果有助於未來決定適當之調控參數，進行有效調控，進而避免心因性猝死之發生。;Nowadays, sudden cardiac (SCD) death is one of top 10 causes of death. Most of them, such as ventricular fibrillation (VF), have a dynamical origin. For example, Ventricular fibrillation has been described as ”chaotic asynchronous fractionated activity of the heart”. According to the non-linear dynamics, that cardiac dynamic would undergo period doubling alternans before getting into chaos. As a result, we could try to reduce the alternans in order to avoid VF. We use single cell and 1-dimension fiber Shiferaw-Fox model, with APD-calcium coupling, to simulate the dynamics of heartbeat and the T +T− feedback control to suppress cardiac alternans. According to the result of our simulations, we found some relationships among basic cycle length, control fraction and critical control strength, and these findings could improve our control to avoid SCD.
