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Summary

Abstract

Introduction

Protocol

Representative Results

Discussion

Acknowledgements

Materials

References

Medicine

Echocardiographic Approaches and Protocols for Comprehensive Phenotypic Characterization of Valvular Heart Disease in Mice

Published: February 14th, 2017

DOI:

10.3791/54110

1Department of Surgery, Mayo Clinic, 2Department of Medicine, Mayo Clinic, 3Department of Physiology & Biomedical Engineering, Mayo Clinic

This protocol provides a detailed description of the echocardiographic approach for comprehensive phenotyping of heart and heart valve function in mice.

The aim of this manuscript and accompanying video is to provide an overview of the methods and approaches used for imaging heart valve function in rodents, with detailed descriptions of the appropriate methods for anesthesia, the echocardiographic windows used, the imaging planes and probe orientations for image acquisition, the methods for data analysis, and the limitations of emerging technologies for the evaluation of cardiac and valvular function. Importantly, we also highlight several future areas of research in cardiac and heart valve imaging that may be leveraged to gain insights into the pathogenesis of valve disease in preclinical animal models. We propose that using a systematic approach to evaluating cardiac and heart valve function in mice can result in more robust and reproducible data, as well as facilitate the discovery of previously underappreciated phenotypes in genetically-altered and/or physiologically-stressed mice.

Aging is associated with progressive increases in cardiovascular calcification1. Hemodynamically significant aortic valve stenosis affects 3% of the population over the age of 652, and patients with even moderate aortic valve stenosis (peak velocity of 3-4 m/s) have a 5 year event-free survival of less than 40%3. Presently, there are no effective treatments to slow the progression of aortic valve calcification, and surgical aortic valve replacement is the only available treatment for advanced aortic valve stenosis4.

Studies aimed at gaining a dee....

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1. Prepare the Materials and Equipment (Table 1 and Figure 1)

  1. Turn on the ultrasound machine. Enter the animal ID, date, and time (for serial imaging experiments) and other relevant information.
  2. Use a high-frequency ultrasound transducer, 40 MHz for imaging mice less than ~20 g or 30 MHz for mice greater than ~20 g.
  3. Connect the platform to the electrocardiogram (ECG) monitor for ECG gating of imaging for certain modalities.
    NOTE: Critically, this also allows for the instantaneous ca.......

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Examples of images that are routinely obtained from animal cardiac ultrasound imaging are included in this manuscript. An illustration of transducer placement on the animal's chest is provided to give the reader a clear understanding of where the transducer is positioned to obtain the images as described. A photograph of the ultrasound laboratory set-up is also included to emphasize the importance of the proper equipment, particularly the ultrasound transducer to be used and the metho.......

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Induction of anesthesia

Proper induction and maintenance of anesthesia is critical for the accurate assessment of changes in heart valve and cardiac function in mice. Given the rapid induction of anesthesia elicited by isoflurane and the relatively long wash-out time of this anesthetic following deep anesthesia, we do not use a stand-alone anesthesia chamber for induction. Instead, as noted in detail above, animals are guided directly to the anesthesia cone, which allows for rapi.......

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This work was supported by NIH grants HL111121 (JDM) and TR000954 (JDM).

....

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Name Company Catalog Number Comments
High resolution ultrasound machine VisualSonics, Fujifilm Vevo 2100 
Isoflurane diffuser (capable of delivering 1 % to 1.5 % isoflurane mixed with 1 L/min 100% O2 VisualSonics, Fujifilm N/A
Transducers for small mice (550D) or larger mice (400) MicroScan, VisualSonics, Fujifilm MS 550D, MS 400
Animal platform VisualSonics, Fujifilm 11503
Advanced physiological monitoring unit VisualSonics, Fujifilm N/A
Isoflurane Terrell NDC 66794-019-10
Nose cone and tubing connected to isoflurane diffuser and 100% O2 Custom Engineered in-house --
Hair razor Andis Super AGR+ vet pack clipper AD65340
Ultrasound gel Parker Laboratories REF 01-08
Electrode gel  Parker Laboratories REF 15-25
Adhesive tapes Fisher Laboratories 1590120B
Paper towels

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