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首页> 外文期刊>Resuscitation. >The effect of ischemia on ventricular fibrillation as measured by fractal dimension and frequency measures.
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The effect of ischemia on ventricular fibrillation as measured by fractal dimension and frequency measures.

机译：通过分形维数和频率测量，可以测量缺血对心室纤颤的影响。

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INTRODUCTION: Most animal studies of ventricular fibrillation (VF) waveform characteristics involve healthy animals with VF initiated by electric shock. However, clinical VF is usually the result of ischemia. The waveform characteristics in these two types of VF may differ. The angular velocity (AV), frequency ratio (FR) and median frequency (MF) are three frequency-based measures of VF. The scaling exponent (ScE), the logarithm of the absolute correlations (LAC) and the Hurst exponent (HE) are three measures of the fractal dimension of VF. HYPOTHESIS: We hypothesized that these quantitative measures would differ between ischemic and electrically initiated VF. METHODS: VF was induced in 14 swine by electric shock and in 12 swine by ischemia. For ischemia induced VF animals, an angioplasty catheter was positioned in the mid-LAD and the balloon inflated. A mean of 891+/-608 (S.D.)s later, VF occurred. For electrically induced animals, an AC current was passed through a catheter in the RV. Following initiation by either method, VF was recorded for 7min. Sequential 5s epochs were analyzed for AV, FR, MF and fractal dimension measures. RESULTS: Ischemic VF demonstrated a significantly higher fractal dimension as estimated by the ScE for the first 0-90s (p=0.021) and for 90-180s (p=0.016). The Hurst exponent was significantly higher for ischemic VF for both 0-90s (p<0.0001) and 90-180s (p<0.0001). The fractal dimension as estimated by the LAC method was not significantly different for 0-90s (p=0.056) but was highly significant for 90-180s (p=0.001). During the initial 90s the groups did differ in all measures of frequency as follows: AV (p<0.001), FR (p<0.001), MF (p<0.001). These differences did not persist beyond 90s except for a mild elevation of the FR after 270s (p<0.02). CONCLUSION: Fractal based measures indicate an increase in the fractal dimension of ischemia induced VF for the first 180s when compared to electrically induced VF. Frequency-based measures uniformly demonstrate a pattern of higher frequencies for electrically induced VF for the first 90s. The increased fractal dimension and decreased frequencies associated with ischemia induced VF may reflect changes in the underlying myocardial physiology that can be used to guide therapies.
机译：简介：大多数动物的心室纤颤（VF）波形特征研究都涉及健康动物，这些动物通过电击引发VF。但是，临床VF通常是缺血的结果。这两种类型的VF中的波形特性可能会有所不同。角速度（AV），频率比（FR）和中频（MF）是VF的三个基于频率的度量。缩放指数（ScE），绝对相关对数（LAC）和赫斯特指数（HE）是VF分形维数的三个度量。假设：我们假设在缺血性和电诱发的室颤之间，这些定量方法会有所不同。方法：电击致14头猪和局部缺血致12头猪的VF。对于缺血诱导的VF动物，将血管成形术导管放置在LAD中部，并将球囊充气。平均891 +/- 608（S.D.）s之后，发生VF。对于电感应动物，交流电流通过RV中的导管。用任何一种方法引发后，记录VF 7分钟。分析了连续5s时期的AV，FR，MF和分形维数度量。结果：缺血性室颤显示分形维数显着较高，由ScE估计，最初的0-90s（p = 0.021）和90-180s（p = 0.016）。缺血性VF的Hurst指数在0-90s（p <0.0001）和90-180s（p <0.0001）时均显着较高。通过LAC方法估计的分形维数在0-90s内无显着差异（p = 0.056），但在90-180s内则显着高（p = 0.001）。在最初的90年代，各组在频率的所有度量上确实有所不同，分别为：AV（p <0.001），FR（p <0.001），MF（p <0.001）。这些差异在90s以后没有持续，除了270s后FR轻度升高（p <0.02）。结论：基于分形的测量表明，与电诱导的VF相比，前180 s缺血诱导的VF的分形维数增加。基于频率的测量一致地证明了在最初90年代电感应VF的较高频率模式。与缺血诱导的VF相关的分形维数增加和频率降低可能反映了潜在的心肌生理学变化，可用于指导治疗。

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