Haq Kazi T, Roberts Anysja, Berk Fiona, Allen Samuel, Swift Luther M, Posnack Nikki Gillum
bioRxiv. 2023 May 2:2023.05.01.538926. doi: 10.1101/2023.05.01.538926.
Cardiac optical mapping is an imaging technique that measures fluorescent signals across a cardiac preparation. Dual optical mapping of voltage-sensitive and calcium-sensitive probes allow for simultaneous recordings of cardiac action potentials and intracellular calcium transients with high spatiotemporal resolution. The analysis of these complex optical datasets is both time intensive and technically challenging; as such, we have developed a software package for semi-automated image processing and analysis. Herein, we report an updated version of our software package ( . ) with features to enhance characterization of cardiac parameters using optical signals.
To test software validity and applicability, we used Langendorff-perfused heart preparations to record transmembrane voltage and intracellular calcium signals from the epicardial surface. Isolated hearts from guinea pigs and rats were loaded with a potentiometric dye (RH237) and/or calcium indicator dye (Rhod-2AM) and fluorescent signals were acquired. We used Python 3.8.5 programming language to develop the . software. Cardiac maps were validated with a user-specified manual mapping approach.
Manual maps of action potential duration (30 or 80% repolarization), calcium transient duration (30 or 80% reuptake), action potential and calcium transient alternans were constituted to validate the accuracy of software-generated maps. Manual and software maps had high accuracy, with >97% of manual and software values falling within 10 ms of each other and >75% within 5 ms for action potential duration and calcium transient duration measurements (n=1000-2000 pixels). Further, our software package includes additional cardiac metric measurement tools to analyze signal-to-noise ratio, conduction velocity, action potential and calcium transient alternans, and action potential-calcium transient coupling time to produce physiologically meaningful optical maps.
. has enhanced capabilities to perform measurements of cardiac electrophysiology, calcium handling, and the excitation-contraction coupling with satisfactory accuracy.
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心脏光学映射是一种测量整个心脏标本荧光信号的成像技术。电压敏感和钙敏感探针的双光学映射允许以高时空分辨率同时记录心脏动作电位和细胞内钙瞬变。对这些复杂的光学数据集进行分析既耗时又具有技术挑战性；因此，我们开发了一个用于半自动图像处理和分析的软件包。在此，我们报告了我们软件包的更新版本（ 。 ），其功能可增强使用光信号对心脏参数的表征。
为了测试软件的有效性和适用性，我们使用Langendorff灌注心脏标本记录心外膜表面的跨膜电压和细胞内钙信号。从豚鼠和大鼠分离的心脏加载电位染料（RH237）和/或钙指示剂染料（Rhod-2AM）并采集荧光信号。我们使用Python 3.8.5编程语言开发 。 软件。心脏图谱通过用户指定的手动映射方法进行验证。
构建了动作电位持续时间（复极化30%或80%）、钙瞬变持续时间（再摄取30%或80%）、动作电位和钙瞬变交替的手动图谱，以验证软件生成图谱的准确性。手动图谱和软件图谱具有很高的准确性，对于动作电位持续时间和钙瞬变持续时间测量（n = 1000 - 2000像素），超过97%的手动和软件值相差在10 ms以内，超过75%相差在5 ms以内。此外，我们的软件包包括额外的心脏指标测量工具，用于分析信噪比、传导速度、动作电位和钙瞬变交替以及动作电位 - 钙瞬变耦合时间，以生成具有生理意义的光学图谱。
。 在进行心脏电生理学、钙处理和兴奋 - 收缩偶联测量方面具有增强的能力，且准确性令人满意。
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