心室除顫系統之功率輸出級設計

Abstract

心臟與神經中的電訊號傳導，是維持生物生理運作正常最根本的基礎。不規則的電訊號傳導在心臟與腦中是危險且致命的。其中，室性快速心律失常更造成了全球每年數十萬起心源性猝死的案例。透過擁有高解析度且不被除顫電擊所干擾的Optical mapping技術，可以觀察到室性快速心律失常的發生與除顫瞬間的膜電位反應，進一步研究更有效安全的除顫方式。 本篇主要提出一心室除顫系統之功率輸出級設計，並探討電擊時間間距和頻率變化對於離體大鼠心臟之反應。系統輸出級採半橋電路設計，透過抬升及引導電路輔助，輸出不同頻率之指數衰減除顫波型。實驗採用S1-S2 protocol的心律失常誘發。S1 pacing間距固定為200ms, S2則分為50, 75, 100, 125, 150ms組，並用以傳統雙向,250Hz,500Hz,1000Hz之除顫電擊。實驗數據指出在特定100ms的S2間距下有最高的心室顫動誘發率。且隨著頻率增加，心室顫動誘發率在1000Hz達到500%的增加。

We proposed a high-frequency ventricular defibrillation system output power stage design and investigated the effects of high-frequency defibrillation on the isolated heart. The high-frequency defibrillation system delivers traditional biphasic, 250Hz exponential decaying, 500Hz exponential decaying, and 1000Hz exponential decaying waveform in: pacing interval S1 fixed to 200ms, S2 interval varying from 50ms to 150ms with 25ms interval condition. Action potential was recorded during and after the defibrillation shock and pacing by optical mapping technology. The highest ventricular fibrillation (VF) induced rate (VF vulnerability) located at S2 interval of 100ms, which increases the VF vulnerability from 4% to 42%. The increasing frequency also shows 500% increasing VF vulnerability from traditional biphasic defibrillation shock. The results suggest that high-frequency defibrillation waveforms could have higher defibrillation efficacy than traditional biphasic waveform.