利用頻譜分析心房顫動之傳導阻滯現象

Frequency Analysis of Conduction Block in Atrial Fibrillation

賴建呈(Chien-Chen Lai)

指導教授 ： 胡威志

中原大學/工學院/醫學工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300129

摘要

摘 要
心房纖維性顫動（Atrial Fibrillation，AF）發生或啟動之假說指出多個活化訊號同時再進入心房傳導的現象，在心房上某些區域發生傳導阻滯(conduction block)造成的現象，研究心房上的傳導阻滯現象以了解心房纖維性顫動成為本論文的一項重點。在AF時，由於多個傳導迴路同時產生心電訊號再進入心肌傳導纖維，使心房去極化心肌組織不停得活化，造成在頻率上的紊亂現象，經頻譜分析後，有多個主要頻率(multi-frequency)參雜在其中，為了解傳導阻滯現象和多頻現象在AF時於心房上的關連，並進一步探討在AF停止前兩者的變化情形。在本實驗中，假設施打抗心律不整藥物後，在藥物的作用下，傳導阻滯的區域雙向阻斷了活化波的傳導，延長其不反應期，造成多頻現象的區塊變的較離散且區塊較小，訊號逐漸變的比較規則，最後導致AF停止。本研究建立一套工具程式，採用多通道15×8電極陣列電流映射系統(cardiac mapping)，電極間距為3mm，選用8筆AF停止前的訊號，每筆訊號為10秒，總共約540次的活化事件，以活化時間及最小傳導速率的標準(10cm/s)，判斷傳導阻滯的電極位置。採用時頻圖方法(STFT)，以閥值判斷方法淬取出在時頻圖上的多主頻現象，找出多頻現象所在電極位置。分析傳導阻滯與多頻現象在AF停止前與在AF時的變化情形，期望以這兩種現象協助使用者了解造成AF停止的原因。分析時以單一活化(single activation)的方式同時觀察等時圖、傳導阻滯與多頻現象的對應關係。經時頻圖閥值方法與傳導阻滯方法判斷的結果說明，圖像上的分布顯示傳導阻滯及多頻現象會以區塊狀（cluster）分布，討論其區塊現象在AF時與在AF最後一跳時的不同，在AF期間的多頻現象平均區塊數與AF最後一跳的區塊數分別為2.24±0.89與3.25±0.71，P<0.01，而平均區塊大小方面，在AF期間與在AF停止前最後一跳時分別為14.92與6.84，P<0.05，可以發現多頻區塊現象在AF停止前最後一跳，區塊數目變多且每個區塊變的較小，說明了多頻區塊現象在AF停止前由原本的大區塊變的離散，導致AF停止。

關鍵字

心電訊號映射 ； 心房纖維性顫動 ； 傳導阻滯 ； 時頻圖分析 ； 多頻現象

並列摘要

Abstract
We have reported a self-developed software data analysis tool that can be used to screen atrium electrical activation in time domain as well as in frequency domain. The extracted data are reconstructed into a conduction delay map and a multi-frequency map for each activation. It is commonly thought that atria fibrillation (AF) is caused by functional reentry circuits of activation pathway. The cause of reentry is thought to be the block of activation wavelet and the conduction wavelet rotating around the excitable tissue. The process of reentry excites atrial myocardium that increases the numbers of activation which exhibits the multi-frequency in spectrum analysis. The slow down of electrical excitation wavelet delays the electrical propagation in part of atrium. The relationship between excitation conduction block and its frequency distribution remains unclear. We hypothesize that the size of multi-frequency cluster should be decrease at the last activation in AF period. Thus, the multi-frequency cluster became smaller as the number of cluster increase. The electric potential of eight canines with electrically-induced AF are recorded using uni-polar electrode 15×8 mapping array on the right atrium epicardium. We have developed a software program to evaluate conduction velocity and analyze the frequency distribution by the short time Fourier transform (STFT). These data are used in the reconstruction of isochronal map, the mapping of conduction block, and the mapping of multi-frequency distribution for every cycling time. The incident of conduction block for every channel is identified using isochronal map with activation time of a minimum conduction velocity criterion (10 cm/s) among the adjacent channels. In order to identify the multi-frequency distribution area, the STFT of each electrogram is analyzed with the amplitude, the frequency separation, and the cycling time duration. The map of conduction block reconstructed from each channel can be grouped into an iso-velocity contour. At the same time period, the multiple frequency analysis using STFT was reconstructed into multi-frequency map. The multi-frequency map reconstructed from each channel also clustered in some groups. The average cluster number are 2.24±0.89 in AF and 3.25±0.71 in the last activation in AF, and P<0.01. The average cluster size are 14.92 in AF and 6.84 in the last activation in AF, and P<0.05. The result has shown that the multi-frequency clusters became more dispersed and each cluster became smaller while at the last activation in AF.

並列關鍵字

Electrical potential ； cardiac mapping ； Atrial Fibrillation ； Time-Frequency analysis ； conduction block

參考文獻

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