Visualizing excitation waves inside cardiac muscle using transillumination
Visualizing excitation waves inside cardiac muscle using transillumination
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DOI：
10.1016/s0006-3495(01)76034-1
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发表时间：
2001-01-01
影响因子：
3.4
通讯作者：
Pertsov, AM
中科院分区：
文献类型：
--
作者：
Baxter, WT;Mironov, SF;Pertsov, AM
电压敏感荧光染料已成为心脏中兴奋传播可视化的有力工具。然而，直到最近它们还专门用于表面录音。在这里，我们演示了通过透照模式下的荧光测量（其中光源和光电探测器位于制备物的相对侧）可视化心肌内部电活动的可能性。该模式能够检测从组织深处逸出的光。实验在用电压敏感染料 di-4-ANEPPS 染色的绵羊右心室壁灌注板（8 毫米厚）中进行。尽管透照模式下记录的幅度和信噪比明显小于落射照明模式下记录的幅度和信噪比，但它们足以可靠地确定激活序列。通过测量心肌中的光衰减得出的穿透深度（空间衰减常数）对于激发波长（520 +/- 30 nm）为 0.8 毫米，对于发射波长（640 +/- 50 nm）为 1.3 毫米。基于 8 毫米厚组织中的这些衰减值对发射荧光的估计表明，90% 的透照信号源自照明表面附近的 4 毫米厚层。所记录信号的 69% 源自大于或等于表面以下 1 毫米的位置。透照记录可以与心内膜和心外膜表面记录相结合以获得关于心肌壁厚度的三维传播的信息。我们展示了一个例子，其中透照揭示了壁内折返，在表面记录中无法检测到。
Voltage-sensitive fluorescent dyes have become powerful tools for the visualization of excitation propagation in the heart. However, until recently they were used exclusively for surface recordings. Here we demonstrate the possibility of visualizing the electrical activity from inside cardiac muscle via fluorescence measurements in the transillumination mode (in which the light source and photodetector are on opposite sides of the preparation). This mode enables the detection of light escaping from layers deep within the tissue. Experiments were conducted in perfused (8 mm thick) slabs of sheep right ventricular wall stained with the voltage-sensitive dye di-4-ANEPPS. Although the amplitude and signal-to-noise ratio recorded in the transillumination mode were significantly smaller than those recorded in the epi-illumination mode, they were sufficient to reliably determine the activation sequence. Penetration depths (spatial decay constants) derived from measurements of light attenuation in cardiac muscle were 0.8 mm for excitation (520 +/- 30 nm) and 1.3 mm for emission wavelengths (640 +/- 50 nm). Estimates of emitted fluorescence based on these attenuation values in 8-mm-thick tissue suggest that 90% of the transillumination signal originates from a 4-mm-thick layer near the illuminated surface. A 69% fraction of the recorded signal originates from greater than or equal to1 mm below the surface. Transillumination recordings may be combined with endocardial and epicardial surface recordings to obtain information about three-dimensional propagation in the thickness of the myocardial wall. We show an example in which transillumination reveals an intramural reentry, undetectable in surface recordings.