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首页> 外文会议>Ultrasonic Imaging and Signal Processing; Progress in Biomedical Optics and Imaging; vol.7 no.33 >Electric Current Mapping using the Acousto-Electric Effect
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Electric Current Mapping using the Acousto-Electric Effect

机译：使用声电效应的电流映射

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摘要

Conventional methods for mapping cardiac current fields lack either spatial resolution (e.g. ECG) or are time consuming (e.g., intra-cardiac catheter electrode mapping). We present a method based on the acousto-electric effect (AEE) with potential for rapid mapping of current fields in the heart with high spatial resolution. The AEE is a pressure-induced conductivity modulation, in which focused ultrasound can be used as a spatially localized pressure source. When an ultrasound beam is focused between a pair of recording electrodes in a homogeneous conductive medium, an induced voltage will be produced due to the pressure-modulated conductivity and local current density. The amplitude of the voltage change should be proportional to fluctuations in current density, such as those generated during the cardiac cycle, in the region of focused ultrasound. Preliminary experiments demonstrate the feasibility of this method. A 540 kHz ultrasound transducer is focused between two tin electrodes lying parallel to the beam axis. These electrodes inject current into a 0.9% saline solution. A pair of insulated stainless steel electrodes exposed at the tip is used to record voltage. To simulate a cardiac current, a low frequency current waveform is injected into the sample such that the peak current density (8 mA/cm~2) approximates cardiac currents. The transducer is pulsed at different delays after waveform initiation. Delays are chosen such that the low frequency waveform is adequately sampled. Using this approach an emulated ECG waveform has been successfully reconstructed from the ultrasound modulated voltage traces.
机译：用于绘制心脏电流场的常规方法缺乏空间分辨率（例如，ECG）或很费时间（例如，心脏内导管电极的绘制）。我们提出了一种基于声电效应（AEE）的方法，具有以高空间分辨率快速映射心脏中电流场的潜力。 AEE是压力引起的电导率调制，其中聚焦超声可用作空间局部压力源。当超声波束聚焦在均质导电介质中的一对记录电极之间时，由于压力调制的电导率和局部电流密度会产生感应电压。电压变化的幅度应与聚焦超声区域中电流密度的波动成正比，例如在心动周期期间产生的波动。初步实验证明了该方法的可行性。 540 kHz超声换能器聚焦在平行于束轴的两个锡电极之间。这些电极将电流注入0.9％的盐溶液中。一对暴露在尖端的绝缘不锈钢电极用于记录电压。为了模拟心脏电流，将低频电流波形注入样品中，以使峰值电流密度（8 mA / cm〜2）接近心脏电流。波形启动后，换能器以不同的延迟脉冲化。选择延迟以充分采样低频波形。使用这种方法，已从超声调制的电压迹线成功重建了仿真的ECG波形。

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