Name: real-time electrocardiogram monitoring during treadmill training in mice
Uploaded: 2022-05-05T15:00:00
Description: Watch this Scientific Journal Video about Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice at JoVE.com

This work was supported by the German Research Foundation (DFG; Clinician Scientist Program in Vascular Medicine (PRIME), MA 2186/14-1 to P. Tomsits), the German Centre for Cardiovascular Research (DZHK; 81X2600255 to S. Clauss), the Corona Foundation (S199/10079/2019 to S. Clauss), and the ERA-NET on Cardiovascular Diseases (ERA-CVD; 01KL1910 to S. Clauss). The funders had no role in manuscript preparation.

All animal procedures were conducted in accordance with the guidelines of the Animal Care and Ethics committee of the University of Munich and all procedures were approved by the Government of Bavaria, Munich, Germany (ROB-55.2-2532.Vet_02-16-200). Four male wildtype in-house bred C57BL/6N mice were used in this study.
1. Preparation and surgical implantation of the transmitter
NOTE: For a detailed protocol of transmitter preparation and implantation ...

Current guidelines recommend regular physical activity as it has been demonstrated to be an important modifier of cardiovascular risk factors30. There is also a growing body of evidence that moderate physical activity may protect against atrial fibrillation (AF) both in primary and secondary prevention31,32,33. On the contrary, endurance athletes such as marathon runners have a higher risk to develop AF i...

Regular physical activity is important for a healthy life. Certain cardiovascular conditions, however, lead to situations where this common-sense agreement is at least questionable. In patients with myocarditis, current data even shows adverse effects of exercise and, thus, it is recommended to pause all exercise for a certain period in these patients1,2,3. In other cardiovascular diseases (CVD) such as inherited arrhythmia syndromes comparatively less evidence on the appropriate level of exercise exists4,5,6,7, making clinical counselling in these cases, mostly for young and physically active patients, very challenging.
Adverse remodeling leading to reduced contractility and heart failure and proarrhythmogenic remodeling leading to arrhythmias and sudden cardiac death have been suggested as hallmarks of exercise-associated harmful effects on the heart8. A large number of studies indicate beneficial effects of moderate exercise over a broad spectrum of different diseases9,10. Extensive training, however, may have detrimental effects on the heart leading to arrhythmias especially in otherwise healthy athletes11. Although structural remodeling processes leading to a vulnerable proarrhythmic substrate production may underlie this paradox situation as demonstrated in marathon runners12, the specific mechanisms of exercise-related adverse remodeling both in healthy people and in patients with cardiovascular diseases remain largely unknown.
In animals, especially in mice, several suitable models have been developed to mimic a broad range of cardiovascular diseases13,14. Also, various exercise models and training protocols have been established in mice15,16,17, including motorized treadmill training, voluntary wheel running (VWR), and swimming17,18. Evaluation of cardiac electrophysiology by ECG monitoring classically depends on a direct conducting connection between the animal and some sort of detection device. Thus, either animals need to be anesthetized, e.g., to obtain ECG recordings using sharp electrodes19, or animals need to be immobilized by a restrainer 20, or data quality is reduced due to motion artifacts, e.g., when using paw-electrodes21 or conductive platforms22 allowing only basic analysis. Thus, none of the above-mentioned approaches are compatible with training protocols and consequently prevent studies on exercise-related mechanisms leading to adverse remodeling in mice. Implantable telemetry devices can overcome these hurdles and are nowadays the most powerful tool and gold standard to evaluate murine electrophysiology in vivo in conscious and moving animals23,24. Current telemetry hardware solutions have been developed to monitor mice in their cages25,26,&#160;and commonly require a receiver to be placed underneath the cage for data acquisition, thus making real-time monitoring outside these circumstances challenging. Here we provide an approach to investigate the effects of exercise on cardiac electrophysiology and arrhythmogenesis by real-time ECG recording during treadmill training in mice using implanted telemetry devices. All parameters obtained were analyzed as previously described by Tomsits et al.23.

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			<td>Data Exchange Matrix 2.0 (MX2)</td>
			<td>Data Science International</td>
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			<td>Manages communication between PhysioTel and PhysioTel HD telemetry implants and the acquisition computer.</td>
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			<td>Fine Science Tools</td>
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			<td>Includes treadmill unit, touchscreen control unit, a sponge , and cables</td>
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			<td>Hugo Sachs Elektronik</td>
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			<td>Modified Bain circuit</td>
			<td>Hugo Sachs Elektronik</td>
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			<td>Includes an anesthesia mask for mice</td>
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			<td>Modular connectors</td>
			<td>Data Science International</td>
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			<td>Connecting cables between Reciever, Signal Interface and Matrix 2.0 (MX2)</td>
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			<td>Novafil s 5-0</td>
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			<td>Octal BioAmp</td>
			<td>ADInstruments</td>
			<td>FE238-0239</td>
			<td>Amplifier for recording Surface ECG</td>
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			<td>Octenisept</td>
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			<td>Linde</td>
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			<td>Includes a pressure regulator</td>
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			<td>PhysioTel ETA-F10 transmitter</td>
			<td>Data Science International</td>
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			<td>PhysioTel receiver RPC-1</td>
			<td>Data Science International</td>
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			<td>Signal reciever</td>
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			<td>Ponemah 6.42</td>
			<td>Data Science International</td>
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			<td>ECG Analysis Software</td>
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			<td>Powerlab</td>
			<td>ADInstruments</td>
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			<td>Suface ECG Acquisition hardware device. Includes ECG electrode leads</td>
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			<td>Prism 8.0.1</td>
			<td>Graph Pad</td>
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			<td>Radio Device (Sony AF/AM)</td>
			<td>Sony</td>
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			<td>Signal Interface</td>
			<td>Data Science International</td>
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			<td>Acquires and synchronizes digital signals with telemetry data in Ponemah v6.x.</td>
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real-time electrocardiogram monitoring during treadmill training in mice

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. However, in certain cardiac diseases such as inherited arrhythmia syndromes, e.g., arrhythmogenic cardiomyopathy (ACM) or myocarditis, physical exercise may have negative effects on the heart leading to a proarrhythmogenic substrate production. Currently, the underlying molecular mechanisms of exercise-related proarrhythmogenic remodeling are largely unknown, thus it remains unclear which frequency, duration, and intensity of exercise can be considered safe in the context of disease(s).
The proposed method allows to study proarrhythmic/antiarrhythmic effects of physical exercise by combining treadmill training with real-time monitoring of the ECG. Implantable telemetry devices are used to continuously record the ECG of freely moving mice over a period of up to 3 months both at rest and during treadmill training. Data acquisition software with its analysis modules is used to analyze basic ECG parameters such as heart rate, P wave duration, PR interval, QRS interval, or QT duration at rest, during and after training. Furthermore, heart rate variability (HRV) parameters and occurrence of arrhythmias are evaluated. In brief, this manuscript describes a step-by-step approach to experimentally explore exercise induced effects on cardiac electrophysiology, including potential proarrhythmogenic remodeling in mouse models.

Depending on individual research objectives, subsequent analysis of obtained telemetry data will differ widely. Here, we demonstrate feasibility of the method by obtaining good quality data recorded during training periods and provide exemplary results of ECGs and heart rate variability analyses before, during, and after training. Data are presented as mean &#177; standard error of mean (SEM), all statistical analyses were conducted with a suitable statistical software (see Table of Materials). Statistic...

Watch this Scientific Journal Video about Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice at JoVE.com

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

Electrocardiogram (ECG) is the key variable to understanding cardiac electrophysiology. Physical exercise has beneficial effects but may also be harmful in the context of cardiovascular diseases. This manuscript provides a method of recording real-time ECG during exercise, which can serve to investigate its effects on cardiac electrophysiology in mice.

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. ...

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