Name: a model of long-term ventricular fibrillation in isolated rat hearts
Uploaded: 2023-02-17T14:15:00
Description: Watch this Scientific Journal Video about A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts at JoVE.com

这项工作得到了中国人民解放军总医院第一医学中心心血管外科和中国人民解放军总医院实验动物中心的支持。

本次调查中使用的所有实验程序和方案均由解放军总医院动物护理和使用委员会审查批准。
1. 准备朗根道夫仪器
<ol><li>准备克雷布斯-亨塞莱特（K-H）缓冲液。要制备 K-H 缓冲液，请在蒸馏水中加入以下内容：118.0 mM NaCl、4.7 mM KCl、1.2 mM MgSO 4、1.2 mM NaH 2 PO4、1.8 mM CaCl2、25.0 mM NaHCO3、11.1 mM 葡萄糖和 0.5 mM EDTA。</li>
	<li>准备?...

<ol>
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M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fifteen-year+experience+with+minimally+invasive+approach+for+reoperations+involving+the+mitral+valve.">Fifteen-year experience with minimally invasive approach for reoperations involving the mitral valve.</a> The Journal of Thoracic and Cardiovascular Surgery. 143 (5), 1062-1068 (2012).</li><li>Cox, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+safety+of+induced+ventricular+fibrillation+during+cardiopulmonary+bypass+in+nonhypertrophied+hearts.">The safety of induced ventricular fibrillation during cardiopulmonary bypass in nonhypertrophied hearts.</a> The Journal of Thoracic and Cardiovascular Surgery. 74 (3), 423-432 (1977).</li><li>Schraut, W., Lamberti, J. J., Kampman, K., Glagov, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ventricular+fibrillation+during+cardiopulmonary+bypass:+Long-term+effects+on+myocardial+morphology+and+function.">Ventricular fibrillation during cardiopulmonary bypass: Long-term effects on myocardial morphology and function.</a> The Annals of Thoracic Surgery. 27 (3), 230-234 (1979).</li><li>Li, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pravastatin+attenuates+cardiac+dysfunction+induced+by+lysophosphatidylcholine+in+isolated+rat+hearts.">Pravastatin attenuates cardiac dysfunction induced by lysophosphatidylcholine in isolated rat hearts.</a> European Journal of Pharmacology. 640 (1-3), 139-142 (2010).</li><li>Lang, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CXCL10/IP-10+neutralization+can+ameliorate+lipopolysaccharide-induced+acute+respiratory+distress+syndrome+in+rats.">CXCL10/IP-10 neutralization can ameliorate lipopolysaccharide-induced acute respiratory distress syndrome in rats.</a> PLoS One. 12 (1), e0169100 (2017).</li><li>Lubbe, W. F., Bricknell, O. L., Marzagao, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ventricular+fibrillation+threshold+and+vulnerable+period+in+the+isolated+perfused+rat+heart.">Ventricular fibrillation threshold and vulnerable period in the isolated perfused rat heart.</a> Cardiovascular Research. 9 (5), 613-620 (1975).</li><li>Hottentrott, C. E., Towers, B., Kurkji, H. J., Maloney, J. V., Buckberg, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+hazard+of+ventricular+fibrillation+in+hypertrophied+ventricles+during+cardiopulmonary+bypass.">The hazard of ventricular fibrillation in hypertrophied ventricles during cardiopulmonary bypass.</a> The Journal of Thoracic and Cardiovascular Surgery. 66 (5), 742-753 (1973).</li><li>Hottenrott, C., Maloney, J. 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The adequately perfused beating, fibrillating, and arrested heart.</a> The Journal of Thoracic and Cardiovascular Surgery. 73 (1), 87-94 (1977).</li><li>Gazmuri, R. J., Berkowitz, M., Cajigas, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+effects+of+ventricular+fibrillation+in+the+isolated+rat+heart.">Myocardial effects of ventricular fibrillation in the isolated rat heart.</a> Critical Care Medicine. 27 (8), 1542-1550 (1999).</li><li>Clasen, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+modified+approach+for+programmed+electrical+stimulation+in+mice:+Inducibility+of+ventricular+arrhythmias.">A modified approach for programmed electrical stimulation in mice: Inducibility of ventricular arrhythmias.</a> PLoS One. 13 (8), e0201910 (2018).</li><li>Diaz-Maue, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+cardiac+rhythm+management+by+applying+optogenetic+multi-site+photostimulation+in+murine+hearts.">Advanced cardiac rhythm management by applying optogenetic multi-site photostimulation in murine hearts.</a> Journal of Visualized Experiments. (174), e62335 (2021).</li><li>Jungen, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+intracardiac+neurons+on+cardiac+electrophysiology+and+arrhythmogenesis+in+an+ex+vivo+Langendorff+system.">Impact of intracardiac neurons on cardiac electrophysiology and arrhythmogenesis in an ex vivo Langendorff system.</a> Journal of Visualized Experiments. 135, e57617 (2018).</li><li>Koretsune, Y., Marban, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+calcium+in+the+pathophysiology+of+ventricular+fibrillation+and+in+the+pathogenesis+of+postarrhythmic+contractile+dysfunction.">Cell calcium in the pathophysiology of ventricular fibrillation and in the pathogenesis of postarrhythmic contractile dysfunction.</a> Circulation. 80 (2), 369-379 (1989).</li><li>Brazier, J. R., Cooper, N., McConnell, D. H., Buckberg, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+of+the+effects+of+hypothermia+on+regional+myocardial+blood+flow+and+metabolism+during+cardiopulmonary+bypass.+III.+Effects+of+temperature,+time,+and+perfusion+pressure+in+fibrillating+hearts.">Studies of the effects of hypothermia on regional myocardial blood flow and metabolism during cardiopulmonary bypass. III. Effects of temperature, time, and perfusion pressure in fibrillating hearts.</a> The Journal of Thoracic and Cardiovascular Surgery. 73 (1), 102-109 (1977).</li><li>von Planta, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiopulmonary+resuscitation+in+the+rat.">Cardiopulmonary resuscitation in the rat.</a> Journal of Applied Physiology. 65 (6), 2641-2647 (1988).</li><li>Luo, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ageing+increases+cardiac+electrical+remodelling+in+rats+and+mice+via+NOX4/ROS/CaMKII-mediated+calcium+signalling.">Ageing increases cardiac electrical remodelling in rats and mice via NOX4/ROS/CaMKII-mediated calcium signalling.</a> Oxidative Medicine and Cellular Longevity. 2022, 8538296 (2022).</li><li>Hohnloser, S., Weirich, J., Antoni, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+direct+current+on+the+electrical+activity+of+the+heart+and+on+its+susceptibility+to+ventricular+fibrillation.">Influence of direct current on the electrical activity of the heart and on its susceptibility to ventricular fibrillation.</a> Basic Research in Cardiology. 77 (3), 237-249 (1982).</li><li>Xie, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-energy+defibrillation+increases+the+severity+of+postresuscitation+myocardial+dysfunction.">High-energy defibrillation increases the severity of postresuscitation myocardial dysfunction.</a> Circulation. 96 (2), 683-688 (1997).</li><li>Manoach, M., Netz, H., Erez, M., Weinstock, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ventricular+self-defibrillation+in+mammals:+Age+and+drug+dependence.">Ventricular self-defibrillation in mammals: Age and drug dependence.</a> Age and Ageing. 9 (2), 112-116 (1980).</li><li>Filippi, S., Gizzi, A., Cherubini, C., Luther, S., Fenton, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+insights+into+hypothermic+ventricular+fibrillation:+The+role+of+temperature+and+tissue+size.">Mechanistic insights into hypothermic ventricular fibrillation: The role of temperature and tissue size.</a> Europace. 16 (3), 424-434 (2014).</li></ol>

该协议在孤立的大鼠心脏中建立了长期VF的动物模型，该模型以前未报道过。此外，本研究还比较了不同的电刺激条件。本研究为心脏手术期间心室颤动骤停相关的研究提供了一个模型。
模型的成功率是非常重要的指标，与人员、时间、经济成本有关。在VF模型中，成功率包括VF是否可以在心脏中诱导以及除颤后心脏是否可以恢复正常跳动。此外，应考虑心功能恢复率和心肌?...

心脏手术通常通过开胸术进行，阻塞主动脉并灌注心脏停滞溶液以阻止心脏。重复心脏手术可能比初始手术更具挑战性，并发症和死亡率更高1，2，3。此外，传统的正中胸骨切开术可能会对胸骨后面的桥血管、升主动脉、右心室和其他重要结构造成损害。结缔组织分离引起的大量出血、胸骨伤口感染和胸骨切开术引起的胸骨骨髓炎都是可能的并发症。大量解剖会增加重要心脏结构病变和出血的风险。
随着微创心脏手术的发展，切口越来越小，有时难以实现心脏骤停。在心室颤动（VF）下重复心脏手术4，5是安全、可行的，并且可以提供更好的心肌保护。因此，该协议介绍了微创体外循环手术中VF心脏骤停的方法。心脏在VF期间失去有效收缩，因此在手术过程中无需缝合和阻塞升主动脉，这简化了手术。然而，即使心脏连续灌注，长期VF仍然可能对心脏有害。
随着这种方法的使用越来越广泛，如何在VF期间保护心脏的问题变得越来越重要。这将需要使用长期VF的动物模型进行广泛而深入的研究。过去，该领域的研究主要使用大型动物6，7，并且需要外科医生，麻醉师，灌注师和其他研究人员之间的合作。这些研究耗时太长，样本量通常很小，研究通常侧重于心脏功能，而不是机制和分子评估。迄今为止，还没有研究报告建立长期VF模型的详细方案。
因此，该协议提供了使用Langendorff装置开发长期VF大鼠模型所需的详细信息。该方案简单、经济、可重复且稳定。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0 Non-absorbable suture</td>
			<td>Ethicon, Inc.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>95% O2 + 5% CO2</td>
			<td>Beijing BeiYang United Gas Co., Ltd.&#160;</td>
			<td></td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>AcqKnowledge software</td>
			<td>BIOPAC Systems Inc.</td>
			<td>Version 4.2.1</td>
			<td>Software</td>
		</tr>
		<tr>
			<td>Automatic biochemistry analyzer</td>
			<td>Rayto Life and Analytical Sciences Co., Ltd.</td>
			<td>Chemray 800</td>
			<td>CK-MB assay</td>
		</tr>
		<tr>
			<td>BIOPAC research systems</td>
			<td>BIOPAC Systems Inc.</td>
			<td>MP150</td>
			<td>Hardware</td>
		</tr>
		<tr>
			<td>Blunt needle (20 G, TWLB)</td>
			<td>Tianjin Hanaco MEDICAL Co., Ltd.</td>
			<td>H-113AP-S</td>
			<td>Modified Langendorff perfusion system</td>
		</tr>
		<tr>
			<td>Calcium chloride</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10005861</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>CK-MB assay kits&#160;</td>
			<td>Changchun Huili Biotech Co., Ltd.</td>
			<td>C060</td>
			<td>CK-MB assay</td>
		</tr>
		<tr>
			<td>Curved forcep</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10009717</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Electrical stimulator</td>
			<td>BIOPAC Systems Inc.</td>
			<td>STEMISOC</td>
			<td>Hardware</td>
		</tr>
		<tr>
			<td>Filter</td>
			<td>Tianjin Hanaco MEDICAL Co., Ltd.</td>
			<td>H-113AP-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>63005518</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Heparin sodium</td>
			<td>Tianjin Biochem Pharmaceutical Co., Ltd.</td>
			<td>H120200505</td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>RWD Life Science Co.,LTD</td>
			<td>21082201</td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Magnesium sulfate</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>20025118</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Needle electrodes</td>
			<td>BIOPAC Systems Inc.</td>
			<td>EL452</td>
			<td>Hardware</td>
		</tr>
		<tr>
			<td>Ophthalmic clamp</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Ophthalmic forceps</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Ophthalmic scissors</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Perfusion tube</td>
			<td>Tianjin Hanaco MEDICAL Co., Ltd.</td>
			<td>H-113AP-S</td>
			<td>Modified Langendorff perfusion system</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10016318</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10018960</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10019318</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Sodium dihydrogen phosphate dihydrate</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>20040718</td>
			<td>K-H buffer</td>
		</tr>
		<tr>
			<td>Sprague-Dawley (SD) rats</td>
			<td>SPF (Beijing) biotechnology Co., Ltd.</td>
			<td>Male, 300-350g</td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Thermometer</td>
			<td>Jiangsu Jingchuang Electronics Co., Ltd.</td>
			<td>GSP-6</td>
			<td>Modified Langendorff perfusion system</td>
		</tr>
		<tr>
			<td>Tissueforceps</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Tissue scissors</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Toothed forceps</td>
			<td>Shanghai Medical Instrument (Group) Co., Ltd.</td>
			<td></td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Ventilator</td>
			<td>Chengdu Instrument Factory</td>
			<td>DKX-150</td>
			<td>Preparation of the isolated heart</td>
		</tr>
		<tr>
			<td>Water bath1</td>
			<td>Ningbo Scientz Biotechnology Co.,Ltd.</td>
			<td>SC-15</td>
			<td>Modified Langendorff perfusion system</td>
		</tr>
		<tr>
			<td>Water bath2</td>
			<td>Shanghai Yiheng Technology Instrument Co., Ltd.</td>
			<td>DK-8D</td>
			<td>Modified Langendorff perfusion system</td>
		</tr>
	</tbody>
</table>

a model of long-term ventricular fibrillation in isolated rat hearts

心室颤动（VF）是一种致命的心律失常，在心脏病患者中发病率很高，但灌注下的VF骤停是心脏外科领域被忽视的术中停搏方法。随着心脏手术的最新进展，对灌注下长期VF研究的需求有所增加。然而，该领域缺乏简单、可靠和可重复的慢性心室颤动动物模型。该方案通过交流电（AC）电刺激心外膜诱导长期VF。采用不同条件诱导VF，包括用低电压或高电压连续刺激以诱导长期VF和用低电压或高压刺激5 min以诱导自发的长期VF。比较不同情况的成功率，以及心肌损伤和心脏功能恢复的发生率。结果表明，连续低压刺激诱导长期VF，5 min低压刺激诱导自发性长期VF，伴轻度心肌损伤，心功能恢复率高。然而，低电压、连续激励的长期VF模型具有较高的成功率。高压刺激提供了更高的VF诱导率，但除颤成功率低，心脏功能恢复不良，心肌损伤严重。基于这些结果，推荐连续低压心外膜交流电刺激，其成功率高，稳定性高，可靠性高，重现性强，对心脏功能影响小，心肌损伤轻。

实验共使用57只大鼠，其中30只符合纳入标准。将纳入的动物分为5组，每组6只：对照组（C组）、低压持续刺激长期VF组（LC组）、高压持续刺激长期VF组（HC组）、低压诱导自发长期VF组（LI组）和高压诱导自发长期VF组（HI组）。每组的实验过程如图 2所示。
VF模型的成功率 VF的比率，除颤的成功率和VF模型的成功率如 表1所示。...

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A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

该协议提出了由低压交流电连续刺激引起的大鼠心脏长期心室颤动的模型。该模型成功率高，稳定可靠，可重复，对心脏功能影响小，仅引起轻度心肌损伤。

孤立大鼠心脏长期心室颤动模型

Ventricular fibrillation (VF) is a fatal arrhythmia with a high incidence in cardiac patients, but VF arrest under perfusion is a neglected method of ...

该协议提供了使用Langendorff装置开发长期心室颤动大鼠模型的详细需求。它填补了小动物模型中长期心室颤动的空白。该技术简单、经济、可重复且稳定。该技术可用于在心脏外科手术和手术领域的某些临床情况下进行灌注下的心室颤动停止的研究。首先，通过在蒸馏水中加入 118 毫摩尔氯化钠、4.7 毫摩尔氯化钾、1.2 毫摩尔氯化镁、1.2 毫摩尔磷酸二氢钠、1.8 毫摩尔氯化钙、25 毫摩尔碳酸氢钠、11.1 毫摩尔葡萄糖和 0.5 毫摩尔 EDTA 来制备 Krebs-Henseleit 或 KH 缓冲液。然后准备改进的朗根道夫灌注系统。在大约80毫米汞柱的压力下，用95%的氧气和5%的二氧化碳连续地向含有KH缓冲液的烧瓶充气。将灌注管的一端放入KH缓冲液中，将灌注管的中间穿过水浴，并将钝的20号针连接到灌注管的另一端。将针头悬挂在金属丝支架上后，调节水浴的温度，使灌注系统末端的KH缓冲液温度为37摄氏度。使用生理信号记录仪将所有模拟信号数字化并记录下来。使用两个不锈钢针电极记录双极心电图或ECG，使用两个不锈钢针电极进行电刺激。将四个电极的一端连接到生理信号记录器，另一端靠近连接到设备后心脏将定位的区域。接下来，使用笔记本电脑软件自动识别、调整和记录双极心电图和血流动力学参数。将电刺激器参数设置为 30 赫兹交流电，低压组接收 2 伏，高压组接收 6 伏。将麻醉的大鼠在颈椎夹层和气管插管后连接到呼吸机上，用齿钳将皮肤从剑突上抬起，并用组织剪刀在皮肤上做一个三厘米的横向切口。将皮肤和肋骨切口以V形延伸至两侧的腋窝。使用钝性夹层将头臂干与周围组织分开。然后用弯曲的镊子夹住头臂躯干，以方便取出心脏。立即将心脏浸入带有0至4摄氏度KH缓冲液的培养皿中，以洗涤并泵出残留的血液。将心脏转移到第二个培养皿中。切断多余的组织并识别主动脉。使用两个眼科钳提起主动脉并将主动脉插入朗根道夫装置的钝针中。然后在助手的帮助下，用 0 缝合线打一个结。打开灌注流量调节器。将球囊通过二尖瓣推入左心室。用蒸馏水填充气球，以达到 5 至 10 毫米汞柱的舒张压结束。将心电图和电刺激电极连接到心脏。将心脏放在保持在 37 摄氏度的夹套玻璃室的中心。让心脏在腔室内平衡 20 分钟。然后调节水浴温度，使夹套玻璃室内的温度保持在30摄氏度。温度达到所需水平后，激活笔记本电脑软件上的电刺激开关。如果动物是持续刺激的长期心室颤动或VF组的一部分，请允许90分钟的电刺激。VF 90 分钟后，使用电极进行 0.1 焦耳的直流除颤。同时，调节水浴温度，使夹套玻璃室内的温度缓慢上升至37摄氏度，持续10分钟。除颤后，让心脏跳动 60 分钟，然后用 10% 氯化钾在大约 37 摄氏度下缓慢灌注停止跳动。取出心脏进行肌酸激酶或 CK-MB 测定和组织学分析。此处显示了 VF 的速率、除颤的成功率和 VF 模型的成功率。LC组和HC组接受连续电刺激，因此VF的成功率为100%。但HC组显示出较低的除颤成功率。5分钟后关闭电刺激的LI组和HI组的VF率不同，但与LC组和HC组相比，两组的VF率均较慢。LC组和LI组都有更好的除颤成功率。但总体而言，LC组的模型成功率最高，而LI组的模型成功率较低。此处显示了心率或心率、冠状动脉血流或CF，以及左心室压差或LVPD恢复率。C组血流动力学在实验期间保持稳定，HR、CF和LVPD略有下降。两组低电压诱导VF性能相似，恢复率较好。与C组相比，这些组的HR和LVPD差异无统计学意义，但CF的恢复率明显优于 C.In 组，高电压诱导长期VF组的血流动力学恢复率较差，高压连续刺激的长期VF组的血流动力学恢复率最差。冠状动脉积液分析显示，两个高压组的CK-MB水平均较高。两低电压组间无差异，C组苏木精和伊红染色显示HC组电极烧伤区。该方案适用于与心室颤动骤停和心血管外科灌注相关的研究。

a-model-of-long-term-ventricular-fibrillation-in-isolated-rat-hearts

Research

JoVE Journal

Medicine

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of cardiovascular disease. Although molecular biology is necessary in identifying key changes in the signaling pathway, it is not a surrogate for functional significance. While physiology can provide answers to the question of function, combining physiology with biochemical assessment of metabolites in the intact, beating heart allows for a complete picture of cardiac function and energetics. For years, our laboratory has utilized isolated heart perfusions combined with nuclear magnetic resonance (NMR) spectroscopy to accomplish this task. Left ventricular function is assessed by Langendorff-mode isolated heart perfusions while cardiac energetics is measured by performing 31P magnetic resonance spectroscopy of the perfused hearts. With these techniques, indices of cardiac function in combination with levels of phosphocreatine and ATP can be measured simultaneously in beating hearts. Furthermore, these parameters can be monitored while physiologic or pathologic stressors are instituted. For example, ischemia/reperfusion or high workload challenge protocols can be adopted. The use of aortic banding or other models of cardiac pathology are apt as well. Regardless of the variants within the protocol, the functional and energetic significance of molecular modifications of transgenic mouse models can be adequately described, leading to new insights into the associated enzymatic and metabolic pathways. Therefore, 31P NMR spectroscopy in the isolated perfused heart is a valuable research technique in animal models of cardiovascular disease.

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Langendorff-mode isolated heart perfusion, in conjunction with 31P NMR spectroscopy, combines the fields of biochemistry and physiology into one experiment. The protocol allows for the dynamic measurement of high energy phosphate content and turnover in the heart while concurrently monitoring physiologic function. When performed correctly, this is a valuable technique in the assessment of cardiac energetics.

在分离的小鼠使用红桃心功能和能量学的评估 31 P核磁共振

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of ...

科研

医学

NADH Fluorescence Imaging of Isolated Biventricular Working Rabbit Hearts

Since its inception by Langendorff1, the isolated perfused heart remains a prominent tool for studying cardiac physiology2. However, it is not well-suited for studies of cardiac metabolism, which require the heart to perform work within the context of physiologic preload and afterload pressures. Neely introduced modifications to the Langendorff technique to establish appropriate left ventricular (LV) preload and afterload pressures3. The model is known as the isolated LV working heart model and has been used extensively to study LV performance and metabolism4-6. This model, however, does not provide a properly loaded right ventricle (RV). Demmy et al. first reported a biventricular model as a modification of the LV working heart model7, 8. They found that stroke volume, cardiac output, and pressure development improved in hearts converted from working LV mode to biventricular working mode8. A properly loaded RV also diminishes abnormal pressure gradients across the septum to improve septal function. Biventricular working hearts have been shown to maintain aortic output, pulmonary flow, mean aortic pressure, heart rate, and myocardial ATP levels for up to 3 hours8.
When studying the metabolic effects of myocardial injury, such as ischemia, it is often necessary to identify the location of the affected tissue. This can be done by imaging the fluorescence of NADH (the reduced form of nicotinamide adenine dinucleotide)9-11, a coenzyme found in large quantities in the mitochondria. NADH fluorescence (fNADH) displays a near linearly inverse relationship with local oxygen concentration12 and provides a measure of mitochondrial redox state13. fNADH imaging during hypoxic and ischemic conditions has been used as a dye-free method to identify hypoxic regions14, 15 and to monitor the progression of hypoxic conditions over time10.
The objective of the method is to monitor the mitochondrial redox state of biventricular working hearts during protocols that alter the rate of myocyte metabolism or induce hypoxia or create a combination of the two. Hearts from New Zealand white rabbits were connected to a biventricular working heart system (Hugo Sachs Elektronik) and perfused with modified Krebs-Henseleit solution16 at 37 &deg;C. Aortic, LV, pulmonary artery, and left &amp; right atrial pressures were recorded. Electrical activity was measured using a monophasic action potential electrode. To image fNADH, light from a mercury lamp was filtered (350&plusmn;25 nm) and used to illuminate the epicardium. Emitted light was filtered (460&plusmn;20 nm) and imaged using a CCD camera. Changes in the epicardial fNADH of biventricular working hearts during different pacing rates are presented. The combination of the heart model and fNADH imaging provides a new and valuable experimental tool for studying acute cardiac pathologies within the context of realistic physiological conditions.

The objective is to monitor the mitochondrial redox state of isolated hearts within the context of physiologic preload and afterload pressures. A biventricular working rabbit heart model is presented. High spatiotemporal resolution fluorescence imaging of NADH is used to monitor the mitochondrial redox state of epicardial tissue.

NADH的荧光成像隔离双心室工作离体兔心

Since its inception by Langendorff1, the isolated perfused heart remains a prominent tool for studying cardiac physiology2. However, it is not well-suited ...

Reduction in Left Ventricular Wall Stress and Improvement in Function in Failing Hearts using Algisyl-LVR

Injection of Algisyl-LVR, a treatment under clinical development, is intended to treat patients with dilated cardiomyopathy. This treatment was recently used for the first time in patients who had symptomatic heart failure. In all patients, cardiac function of the left ventricle (LV) improved significantly, as manifested by consistent reduction of the LV volume and wall stress. Here we describe this novel treatment procedure and the methods used to quantify its effects on LV wall stress and function.
Algisyl-LVR is a biopolymer gel consisting of Na+-Alginate and Ca2+-Alginate. The treatment procedure was carried out by mixing these two components and then combining them into one syringe for intramyocardial injections. This mixture was injected at 10 to 19 locations mid-way between the base and apex of the LV free wall in patients.
Magnetic resonance imaging (MRI), together with mathematical modeling, was used to quantify the effects of this treatment in patients before treatment and at various time points during recovery. The epicardial and endocardial surfaces were first digitized from the MR images to reconstruct the LV geometry at end-systole and at end-diastole. Left ventricular cavity volumes were then measured from these reconstructed surfaces.
Mathematical models of the LV were created from these MRI-reconstructed surfaces to calculate regional myofiber stress. Each LV model was constructed so that 1) it deforms according to a previously validated stress-strain relationship of the myocardium, and 2) the predicted LV cavity volume from these models matches the corresponding MRI-measured volume at end-diastole and end-systole. Diastolic filling was simulated by loading the LV endocardial surface with a prescribed end-diastolic pressure. Systolic contraction was simulated by concurrently loading the endocardial surface with a prescribed end-systolic pressure and adding active contraction in the myofiber direction. Regional myofiber stress at end-diastole and end-systole was computed from the deformed LV based on the stress-strain relationship.

This article describes procedures for implanting a novel hydrogel in failing hearts and quantifying its effect on left ventricular wall stress and function. These procedures have been successfully applied in dogs and humans.

左室壁应力和改进功能衰竭心脏使用Algisyl LVR减少

Injection of  Algisyl-LVR, a treatment under clinical development, is intended to treat  patients with dilated cardiomyopathy. This treatment was recently ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

的隔离方法<em&gt;离体</em&gt;肺灌注的大鼠模型：教训制定鼠EVLP课程中学

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

A Rat Model of Ventricular Fibrillation and Resuscitation by Conventional Closed-chest Technique

A rat model of electrically-induced ventricular fibrillation followed by cardiac resuscitation using a closed chest technique that incorporates the basic components of cardiopulmonary resuscitation in humans is herein described. The model was developed in 1988 and has been used in approximately 70 peer-reviewed publications examining a myriad of resuscitation aspects including its physiology and pathophysiology, determinants of resuscitability, pharmacologic interventions, and even the effects of cell therapies. The model featured in this presentation includes: (1) vascular catheterization to measure aortic and right atrial pressures, to measure cardiac output by thermodilution, and to electrically induce ventricular fibrillation; and (2) tracheal intubation for positive pressure ventilation with oxygen enriched gas and assessment of the end-tidal CO2. A typical sequence of intervention entails: (1) electrical induction of ventricular fibrillation, (2) chest compression using a mechanical piston device concomitantly with positive pressure ventilation delivering oxygen-enriched gas, (3) electrical shocks to terminate ventricular fibrillation and reestablish cardiac activity, (4) assessment of post-resuscitation hemodynamic and metabolic function, and (5) assessment of survival and recovery of organ function. A robust inventory of measurements is available that includes &#8211; but is not limited to &#8211; hemodynamic, metabolic, and tissue measurements. The model has been highly effective in developing new resuscitation concepts and examining novel therapeutic interventions before their testing in larger and translationally more relevant animal models of cardiac arrest and resuscitation.

This article describes a rat model of electrically-induced ventricular fibrillation and resuscitation by chest compression, ventilation, and delivery of electrical shocks that simulates an episode of sudden cardiac arrest and conventional cardiopulmonary resuscitation. The model enables gathering insights on the pathophysiology of cardiac arrest and exploration of new resuscitation strategies.

室颤由传统的封闭胸技术大鼠模型和复苏

A rat model of electrically-induced ventricular fibrillation followed by cardiac resuscitation using a closed chest technique that incorporates the basic ...

Induction and Assessment of Ischemia-reperfusion Injury in Langendorff-perfused Rat Hearts

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for myocardial infarction and cardiac complications of thoracic surgery. The ability of certain drugs to precondition the myocardium against ischemia reperfusion injury has led to multiple clinical trials, with little success. The isolated heart model allows acute observation of the functional effects of ischemia reperfusion injury in real time, including the effects of various pharmacological interventions administered at any time-point before or within the ischemia-reperfusion injury window. Since brief periods of ischemia can precondition the heart against ischemic injury, in situ aortic cannulation is performed to allow for functional assessment of non-preconditioned myocardium. A saline filled balloon is placed into the left ventricle to allow for real-time measurement of pressure generation. Ischemic injury is simulated by the cessation of perfusion buffer flow, followed by reperfusion. The duration of both ischemia and reperfusion can be modulated to examine biochemical events at any given time-point. Although the Langendorff isolated heart model does not allow for the consideration of systemic events affecting ischemia and reperfusion, it is an excellent model for the examination of acute functional and biochemical events within the window of ischemia reperfusion injury as well as the effect of pharmacological intervention on cardiac pre- and postconditioning. The goal of this protocol is to demonstrate how to perform in situ aortic cannulation and heart excision followed by ischemia/reperfusion injury in the Langendorff model.

The isolated rat heart is an enduring model for ischemia reperfusion injury. Here, we describe the process of harvesting the beating heart from a rat via in situ aortic cannulation, Langendorff perfusion of the heart, simulated ischemia-reperfusion injury, and infarct staining to confirm the extent of ischemic insult.

诱导和缺血再灌注损伤评估中的Langendorff灌注鼠心

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for ...

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early cardiopulmonary dysfunction is difficult to diagnose, particularly in animal models, as cardiopulmonary function is often measured invasively, requiring anesthesia. As many anesthetic agents are cardiodepressive, subtle changes in cardiovascular function may be masked. In contrast, chronic instrumentation allows for measurement of cardiopulmonary function in the awake state, so that measurements can be obtained under quiet resting conditions, without the effects of anesthesia and acute surgical trauma. Furthermore, when animals are properly trained, measurements can also be obtained during graded treadmill exercise.
Flow probes are placed around the aorta or pulmonary artery for measurement of cardiac output and around the left anterior descending coronary artery for measurement of coronary blood flow. Fluid-filled catheters are implanted in the aorta, pulmonary artery, left atrium, left ventricle and right ventricle for pressure measurement and blood sampling. In addition, a 20 G&#160;catheter is positioned in the anterior interventricular vein to allow coronary venous blood sampling.
After a week of recovery, swine are placed on a motor-driven treadmill, the catheters are connected to pressure and flow meters, and swine are subjected to a five-stage progressive exercise protocol, with each stage lasting 3 min. Hemodynamic signals are continuously recorded and blood samples are taken during the last 30 sec of each exercise stage.
The major advantage of studying chronically instrumented animals is that it allows serial assessment of cardiopulmonary function, not only at rest but also during physical stress such as exercise. Moreover, cardiopulmonary function can be assessed repeatedly during disease development and during chronic treatment, thereby increasing statistical power and hence limiting the number of animals required for a study.

Here we present a protocol to assess cardiopulmonary function in awake swine, at rest and during graded treadmill exercise. Chronic instrumentation allows for repeated hemodynamic measurements uninfluenced by cardiodepressive anesthetic agents.

导管手术放置了长期的心血管运动试验猪

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early ...

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require&#160;artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

The goal of this protocol is to assess systemic blood pressure in conscious freely moving mice using implantable radio-telemetry devices.

自由活动小鼠使用遥测长期血压测量

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. ...

The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. After isolation and retrograde perfusion of the heart according to the Langendorff technique, the heart is inverted into an upside-down position and is mechanically stabilized by a balloon catheter inserted into the left ventricle. Then, a thin latex cap &#8211; previously cast to match the average size of the rat heart &#8211; is placed over the epicardial surface. The outlet of the latex cap is connected to silicon tubing, with the distal opening 10 cm below the base level of the heart, creating slight suction. CT continuously produced on the epicardial surface is collected in ice-cooled vials for further analysis. The rate of CT formation ranged from 17 to 147 &#181;L/min (n = 14) in control and infarcted hearts, which represents 0.1-1% of the coronary venous effluent perfusate. Proteomic analysis and high performance liquid chromatography (HPLC) revealed that the collected CT contains a wide spectrum of proteins and purinergic metabolites.

This protocol describes a method to collect cardiac interstitial fluid from the isolated, perfused rat heart. To physically separate interstitial transudate from coronary venous effluent perfusate, the Langendorff perfused heart is inverted, and the transudate (interstitial fluid) formed on the cardiac surface is collected using a soft latex cap.

从孤立的大鼠心脏的间质渗出物收集的倒置心脏模型

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. ...

Standardized Model of Ventricular Fibrillation and Advanced Cardiac Life Support in Swine

Cardiopulmonary resuscitation after cardiac arrest, independent of its origin, is a regularly encountered medical emergency in hospitals as well as preclinical settings. Prospective randomized trials in human subjects are difficult to design and ethically ambiguous, which results in a lack of evidence-based therapies. The model presented in this report represents one of the most common causes of cardiac arrests, ventricular fibrillation, in a standardized setting in a large animal model. This allows for reproducible observations and various therapeutic interventions under clinically accurate conditions, hence facilitating the generation of better evidence and eventually the potential for improved medical treatment.

Cardiopulmonary resuscitation and defibrillation are the only effective therapeutic options during cardiac arrest caused by ventricular fibrillation. This model presents a standardized regimen to induce, assess, and treat this physiological state in a porcine model, thus providing a clinical approach with various opportunities for data collection and analysis.

猪心室颤动和高级心脏生命支持标准化模型

Cardiopulmonary resuscitation after cardiac arrest, independent of its origin, is a regularly encountered medical emergency in hospitals as well as ...