心脏压力容量环分析小鼠使用电导导管
Summary
Cardiac pressure-volume loop analysis is the most comprehensive way to measure cardiac function in the intact heart. We describe a technique to perform and analyze cardiac pressure volume loops, using conductance catheters.
Abstract
Cardiac pressure-volume loop analysis is the “gold-standard” in the assessment of load-dependent and load-independent measures of ventricular systolic and diastolic function. Measures of ventricular contractility and compliance are obtained through examination of cardiac response to changes in afterload and preload. These techniques were originally developed nearly three decades ago to measure cardiac function in large mammals and humans. The application of these analyses to small mammals, such as mice, has been accomplished through the optimization of microsurgical techniques and creation of conductance catheters. Conductance catheters allow for estimation of the blood pool by exploiting the relationship between electrical conductance and volume. When properly performed, these techniques allow for testing of cardiac function in genetic mutant mouse models or in drug treatment studies. The accuracy and precision of these studies are dependent on careful attention to the calibration of instruments, systematic conduct of hemodynamic measurements and data analyses. We will review the methods of conducting pressure-volume loop experiments using a conductance catheter in mice.
Introduction
心脏压力容积环分析提供心脏功能的详细信息，其中的金标准功能评估1。虽然诸如超声心动图或心脏MRI成像技术提供的功能的措施，这些措施在很大程度上取决于负载条件。心脏收缩和舒张的负载独立的措施需要心室压力和体积的关系在一定范围内的前后负荷的动态测量。压力容积关系的这种认识源于佐川急便和同事2,3的开创性工作。他们在体外灌注犬心脏表明，压力容积环衍生收缩措施是独立的负载条件4。
在这些分析的体内应用成为可能的传导导管在20世纪80年代的发展。这使得嘉的技术进步SS和他的同事进行的人类5,6压力-容积环分析。电导导管和改进手术技术在上世纪90年代7小型化由啮齿类动物心脏功能分析是可行的，允许遗传和药理学研究被执行。这一进步此后引发广泛使用的压力容积环分析，并产生了大量的洞察哺乳动物心脏生理。
在使用电导导管，并从中获得的数据的解释的一个关键概念是体积和电导之间的关系。电导是负相关的电压，这是使用与近侧放置电极，通常放在下面的主动脉瓣，和远侧，在LV尖8的导管测量。被改变电压或电导的变化电流从近端到远端电极的测量。虽然血池贡献š显著电导，心室壁的贡献，称为并联电导（V p）的 ，以测得的电导必须减去，以获得绝对的LV体积测量。
所述的方法来执行此校正，称为盐水校准，在下面的协议进行了讨论。电导和体积之间的数学关系，由班和同事描述的是体积= 1 /α; （ρL 2）（GG p），其中 α=均匀的场校正系数，ρ=电阻率血液，L为电极之间的距离，G =电导和 G p值=非血液电导9。值得注意的是，在小鼠的统一场校正系数接近1.0，由于小室容积10。再加上压力传感器，电导导管提供实时同步的压力和体积数据。
心脏PRESSU再卷分析呈现特别优势的心脏功能的其他措施，因为它们允许用于心室功能独立的负载条件和心脏速率的测量。收缩的具体负载无关的心脏指标包括：收缩末期压力容积关系（ESPVR），D P / D T最大末端舒张末期容积关系，最大顺应性（E max）和预加载recruitable工作行程（PRSW）。舒张功能的负载无关的指标是舒张末期压力容积关系（EDPVR）11。以下协议描述心脏的压力容积环分析的行为，同时使用一个颈动脉和顶部的方法。虽然进行这些研究的方法进行了详细先前8,11进行了说明，我们将审查的关键步骤，以获得精确的压力容积测量，包括盐水和试管校准修正，并提供THES的可视化演示Ë程序。研究与开展这项研究的动物按批准的方案和杜克大学医学中心的机构动物护理和使用委员会的动物福利法规进行处理。
Protocol
Representative Results
Discussion
我们描述了使用小鼠电导导管，以获得两个心脏收缩和舒张的综合分析perfoming压力 – 容积环分析的方法。菅佐川急便和他 的同事利用压力容积循环，以确定心脏收缩的措施，在ESPVR专门的坡度，或收缩末期弹性（E ES）和E 最大 。顺应性，通过压力的比率定义为体积（P / V），上变化收缩的持续时间。在每个心脏收缩，瞬时弹性度是依赖于心脏速率和心肌收缩力，但在很大程度…
Divulgaciones
The authors have nothing to disclose.
Acknowledgements
这项工作是由美国心脏协会14FTF20370058（DMA）和美国国立卫生研究院T32 HL007101-35（DMA）的支持。
Materials
| AnaSed (xylazine) | Lloyd Laboratories | NADA no. 139-236 | Anesthetic |
| Ketaset (ketamine) | Pfizer | 440842 | Anesthetic |
| VIP3000 | Matrx Medical Inc. | Anesthesia machine | |
| Ventilator | Harvard Apparatus | Model 683 | Surgical Equipment |
| Tubing kit | Harvard Apparatus | 72-1049 | Surgical Equipment |
| Homeothermic Blanket | Kaz Inc. | 5628 | Surgical Equipment |
| Stereo microscope | Carl Zeiss Optical Inc. | Stemi 2000 | Surgical Equipment |
| Illuminator | Cole–Parmer | 41720 | Surgical Equipment |
| Dumont no. 55 Dumostar Forceps | Fine Science Tools Inc | 11295-51 | Surgical Instruments |
| Graefe forceps, curved | Fine Science Tools Inc | 11052-10 | Surgical Instruments |
| Moria MC31 forceps | Fine Science Tools Inc | 11370-31 | Surgical Instruments |
| Mayo scissors | Fine Science Tools Inc | 14512-15 | Surgical Instruments |
| Iris scissors | Fine Science Tools Inc | 14041-10 | Surgical Instruments |
| Halsey needle holder | Fine Science Tools Inc | 12501-13 | Surgical Instruments |
| Olsen–Hegar needle holder | Fine Science Tools Inc | 12002-12 | Surgical Instruments |
| spring scissors | Fine Science Tools Inc | 15610-08 | Surgical Instruments |
| disposable underpads | Kendall/Tyco Healthcare | 1038 | Surgical Supplies |
| Sterile gauze sponges, sterile | Dukal | 62208 | Surgical Supplies |
| Cotton-tipped applicators, sterile | Solon | 368 | Surgical Supplies |
| Surgical suture, silk, 6-0 | DemeTECH | FT-639-1 | Surgical Supplies |
| 1 cc Insulin syringes | Becton Dickenson | 329412 | Surgical Supplies |
| Access-9™ Hemostasis Valve | Merit Medical | MAP111 | Hemodynamic equipment |
| Sphygmomanometer | Baumanometer | 320 | Hemodynamic equipment |
| Millar PV system MPVS-300/400 or MPVS Ultra (includes calibration cuvette) | ADInstruments Inc | Hemodynamic equipment | |
| 1.4F conductance catheter | ADInstruments Inc | SPR-839 | Hemodynamic equipment |
| PowerLab 4/30 with Chart Pro | ADInstruments Inc. | ML866/P | Hemodynamic software |
| animal clipper | Wahl | 8787-450A | Miscellaneous |
| Intradermic tubing PE-10 (Becton Dickinson, cat. no. ) | Becton Dickenson | 427401 | Miscellaneous |
| Intradermic tubing PE-50 (Becton Dickinson, cat. no.) | Becton Dickenson | 427411 | Miscellaneous |
| Needle assortment (18, 25 and 30 gauge; Thomas Scientific) | Miscellaneous | ||
| 0.9% (wt/vol) sodium chloride injection, USP , cat. no. ) | Hospira | NDC no. 0409-4888-50 | Miscellaneous |
| Surgical tape | Miscellaneous | ||
| Alconox (Alconox Inc.) for catheter cleaning | ADInstruments Inc. | Miscellaneous |
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