优化经食管心房起搏以评估小鼠心房颤动易感性
Summary
本协议描述了使用经食管心房起搏评估小鼠心房颤动易感性时实验参数的优化。
Abstract
心房颤动（AF）的遗传和获得性危险因素的小鼠模型已被证明在研究心房颤动的分子决定因素方面很有价值。程序性电刺激可以使用经食管心房起搏作为生存程序进行，从而能够在同一动物中进行连续测试。然而，存在许多起搏方案，这使得重现性复杂化。本协议旨在提供一种标准化策略来开发特定于模型的实验参数，以提高研究之间的可重复性。进行初步研究以优化所研究特定模型的实验方法，包括研究时的年龄、性别和起搏方案的参数（例如，起搏模式和 AF 易感性的定义）。重要的是，应注意避免高刺激能量，因为这会导致神经节丛刺激，伴有无意的副交感神经激活，表现为起搏期间夸张的房室传导阻滞，并且通常与人为心房颤动感应有关。必须将表现出这种并发症的动物排除在分析之外。
Introduction
心房颤动（AF）是多种获得性和遗传性危险因素的最终常见途径。对于研究AF底物病理生理机制的研究，小鼠模型是有利的，因为易于遗传操作，并且通常，它们再现了在人类中观察到的不同临床表型1，2，3的AF敏感性。然而，小鼠很少发生自发性AF4，需要使用激发性心房起搏研究。
可以使用心内5 或经食管6 起搏进行程序性电刺激 （PES） 以评估鼠心房电生理学和 AF 易感性。虽然经食管方法作为生存程序特别有利，但由于许多已发表的实验方案7，8和可能阻碍可重复性的变异源9，其使用变得复杂。此外，有限的报告方案比较使得选择合适的起搏方案具有挑战性。
目前的协议旨在利用系统策略开发模型特异性经食管PES方法来评估鼠AF敏感性，以提高可重复性。重要的是，进行初步试点研究以通过考虑年龄、性别和起搏模式变异性来优化起搏方案，起搏旨在最大限度地减少可能混淆结果的无意副交感神经刺激9.
Protocol
该程序已获得范德比尔特机构动物护理和使用委员会的批准，并且与实验动物护理和使用指南一致。该方案是使用遗传9 和获得的10 （例如高血压）小鼠AF易感性模型开发的。操作员对所研究小鼠的表型视而不见。 1. 动物选择 对于遗传模型，如下所述每两周（即每隔一周）对小鼠进行心房起搏（参见步骤6），以确定AF易…
Representative Results
经食管心房起搏研究通过确定SNRT和AVERP以及AF易感性6 来评估SA和AV淋巴结的电生理学特性（图1）。心电图记录可以测量 P 波持续时间、PR 间期、QRS 持续时间和 QT/QTc 间期。在快速心房起搏期间连续记录心电图可以提供以下 AF 脆弱性测量值：研究期间诱导的发作次数、发作的累积和平均持续时间以及持续 AF 发作的次数。起搏期间过度房室传导阻滞的发作可?…
Discussion
经食管心房起搏不仅允许在同一动物中进行连续研究，而且其持续时间通常比心内检查短（~20 min），从而最大限度地减少麻醉剂的使用及其对电生理参数的影响。
针对每个单独的小鼠模型最初优化方法至关重要。衰老增加了正常小鼠的AF诱导性18，19，并且个体遗传模型可能在有限的时间内显示出AF诱导性。每隔一周进行一次试点?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
图 2 是使用 BioRender.com 创建的。这项工作得到了美国国立卫生研究院国家心肺血液研究所（HL096844和HL133127）的资助;美国心脏协会（2160035，18SFRN34230125和903918[MBM]）;以及美国国立卫生研究院国家转化科学促进中心（UL1 TR000445）。
Materials
| 27 G ECG electrodes | ADInstruments | MLA1204 | |
| 2-F octapolar electrode catheter | NuMED | CIBercath | |
| Activated carbon canister | VetEquip | 931401 | |
| Analysis software | ADInstruments | LabChart v8.1.13 | |
| Biological amplifier | ADInstruments | FE231 | |
| Data acquisition hardware | ADInstruments | PowerLab 26T | |
| Eye ointment | MWI Veterinary | NC1886507 | |
| Heating pad | Braintree Scientific | DPIP | |
| Isoflurane | Piramal | 66794-017-25 | |
| Stimulator | Bloom Associates | DTU-210 | |
| Stimulus Isolator | World Precision Instruments | Model A365 |
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Citazione di questo articolo
Murphy, M. B., Kim, K., Kannankeril, P. J., Murray, K. T. Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice. J. Vis. Exp. (184), e64168, doi:10.3791/64168 (2022).