Name: cardiac pressure-volume loop analysis using conductance catheters in mice
Uploaded: 2015-09-17T14:00:00
Description: Watch this Scientific Journal Video about Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice at JoVE.com

This work is supported by the American Heart Association 14FTF20370058 (DMA) and NIH T32 HL007101-35 (DMA).

1. Conductance Catheter Preparations and Pressure Calibration
<ol>
	<li>Connect conductance catheter to the hemodynamic catheter module. Electronically calibrate pressure and volume measurements by recording preset pressure and volume set on the catheter module. Record a tracing of 0 mm Hg and 25 mm Hg (Figure 1A) and assign voltages to both pressure tracings (Figure&#160;1B and 1C). Similarly, record a volume tracing of 5 RVU and 25 RVU (Figure 1D) and assign voltages...

<ol>
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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=beta-Arrestin-biased+AT1R+stimulation+promotes+cell+survival+during+acute+cardiac+injury.">beta-Arrestin-biased AT1R stimulation promotes cell survival during acute cardiac injury.</a> Am J Physiol Heart Circ Physiol. 303 (8), H1001-H1010 (2012).</li><li>Suga, H., Sagawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mathematical+Interrelationship+between+Instantaneous+Ventricular+Pressure-Volume+Ratio+and+Myocardial+Force-Velocity+Relation.">Mathematical Interrelationship between Instantaneous Ventricular Pressure-Volume Ratio and Myocardial Force-Velocity Relation.</a> Annals of Biomedical Engineering. 1 (2), 160-181 (1972).</li><li>Suga, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ventricular+energetics.">Ventricular energetics.</a> Physiol Rev. 70 (2), 247-277 (1990).</li><li>Kass, D. 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We describe a method for perfoming pressure-volume loop analysis using a conductance catheter in mice, to derive comprehensive analyses of both cardiac contractility and relaxation. Suga, Sagawa and colleagues utilized pressure-volume loops to define measures of cardiac contractility, specifically the slope of the ESPVR, or the end-systolic elastance (Ees), and Emax. Elastance, defined by the ratio of pressure to volume (P/V), varies over the duration of systole. During each systole, the instantaneo...

Cardiac pressure volume loop analysis provides detailed information of cardiac function and are the gold standard for functional assessment 1. While imaging techniques such as echocardiography or cardiac MRI provide functional measures, these measures are highly dependent on loading conditions. Load-independent measures of cardiac contractility and relaxation require dynamic measurements of the ventricular pressure and volume relation over a range of preload and afterload. This understanding of the pressure-volume relation arises from the groundbreaking work of Sagawa and colleagues 2,3. They demonstrated in ex vivo perfused canine hearts that the pressure-volume loop derived contractility measures were independent of loading conditions 4.
In vivo application of these analyses became possible with the development of conductance catheters in the 1980s. This technical advance allowed Kass and colleagues to perform pressure-volume loop analysis in humans 5,6. Miniaturization of conductance catheters and improvements in surgical techniques in the late 1990&#8217;s 7 made analysis of rodent cardiac function feasible, allowing for genetic and pharmacologic studies to be performed. This advance has since lead to the widespread use of pressure-volume loop analysis and has generated a great deal of insight into mammalian cardiac physiology.
A key concept in the use of conductance catheters and the interpretation of data obtained from it is the relationship between volume and conductance. Conductance is inversely related to voltage, which is measured using a catheter with electrodes placed proximally, usually placed below the aortic valve, and distally, at the LV apex 8. Changes in voltage or conductance are measured by changes in current flowing from proximal to distal electrode. Although the blood pool contributes significantly to conductance, the contribution of the ventricular wall, termed parallel conductance (Vp), to measured conductance must be subtracted to obtain absolute LV volume measurements.
The methods to perform this correction, called a saline calibration, are discussed in the protocol below. The mathematical relationship between conductance and volume, described by Baan and colleagues, is that volume=1/&#945;; (&#961;L2)(G-Gp), where &#945;=uniform field correction factor, &#961;=blood resistivity, L=distance between the electrodes, G=conductance and Gp=non-blood conductance 9. Of note, the uniform field correction factor in mice approaches 1.0 due to small chamber volumes10. Coupled with pressure transducers, the conductance catheter provides real time simultaneous pressure and volume data.
Cardiac pressure-volume analysis presents particular advantages over other measures of cardiac function, as they allow for measurement of ventricular function independent of loading conditions and of heart rate. Specific load-independent cardiac indices of contractility include: end-systolic pressure volume relation (ESPVR), dP/dtmax&#8211;end-diastolic volume relation, maximal elastance (Emax) and preload recruitable stroke work (PRSW). A load-independent measure of diastolic function is the end-diastolic pressure volume relationship (EDPVR) 11. The following protocol describes the conduct of cardiac pressure volume loop analysis, using both a carotid and an apical approach. While the methodology to perform these studies have been described in detail previously 8,11, we will review key steps to obtain precise pressure-volume measurements, including both saline and cuvette calibration correction, and provide a visual demonstration of these procedures. &#160;&#160;Research with animals carried out for this study was handled according to approved protocols and animal welfare regulations of Duke University Medical Center&#8217;s Institutional Animal Care and Use Committee.

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			<td>Kaz Inc.</td>
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			<td>Carl Zeiss Optical Inc.</td>
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			<td>Fine Science Tools Inc</td>
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			<td>Kendall/Tyco Healthcare</td>
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			<td>Solon</td>
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			<td>Surgical suture,&#160; silk, 6-0&#160;</td>
			<td>DemeTECH</td>
			<td>FT-639-1</td>
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			<td>1 cc Insulin syringes&#160;</td>
			<td>Becton Dickenson</td>
			<td>329412</td>
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			<td>Access-9&#8482; Hemostasis Valve</td>
			<td>Merit Medical&#160;</td>
			<td>MAP111</td>
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			<td>Sphygmomanometer</td>
			<td>Baumanometer</td>
			<td>320</td>
			<td>Hemodynamic equipment</td>
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			<td>Millar PV system MPVS-300/400 or MPVS Ultra (includes calibration cuvette)</td>
			<td>ADInstruments Inc</td>
			<td></td>
			<td>Hemodynamic equipment</td>
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			<td>1.4F conductance catheter&#160;</td>
			<td>ADInstruments Inc</td>
			<td>SPR-839</td>
			<td>Hemodynamic equipment</td>
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			<td>ADInstruments Inc.</td>
			<td>ML866/P</td>
			<td>Hemodynamic software</td>
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			<td>animal clipper</td>
			<td>Wahl</td>
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			<td>Becton Dickenson</td>
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			<td>Intradermic tubing PE-50 (Becton Dickinson, cat. no.)</td>
			<td>Becton Dickenson</td>
			<td>427411</td>
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			<td>Needle assortment (18, 25 and 30 gauge; Thomas Scientific)</td>
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			<td>0.9% (wt/vol) sodium chloride injection, USP , cat. no. )</td>
			<td>Hospira</td>
			<td>NDC no. 0409-4888-50</td>
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			<td>Alconox (Alconox Inc.) for catheter cleaning</td>
			<td>ADInstruments Inc.</td>
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cardiac pressure-volume loop analysis using conductance catheters in mice

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; 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.

Pressure-volume loop analysis can be used to measure cardiac function in genetically modified mice 14,15 or mice undergoing drug studies16. Representative pressure volume loops are provided from previously published work 16 investigating the effect of &#223;-Arrestin biased AT1R ligand, TRV120023. To test whether TRV120023 affects cardiac function in vivo, pressure-volume loop analysis was performed on wild type mice receiving conventional and novel angiotensin receptor blockers....

Watch this Scientific Journal Video about Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice at JoVE.com

Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice

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.

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular ...

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Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice

Papillary muscle isolated from adult mouse hearts can be used to study cardiac contractility during different physiological/pathological conditions. The ...

Measuring Pressure Volume Loops in the Mouse

Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the ...