Noninvasive method for electrocardiogram recording in conscious rats: feasibility for heart rate variability analysis

Abstract

Heart rate variability (HRV) analysis consists in a well-established tool for the assessment of cardiac autonomic control, both in humans and in animal models. Conventional methods for HRV analysis in rats rely on conscious state electrocardiogram (ECG) recording based on prior invasive surgical procedures for electrodes/transmitters implants. The aim of the present study was to test a noninvasive and inexpensive method for ECG recording in conscious rats, assessing its feasibility for HRV analysis. A custom-made elastic cotton jacket was developed to fit the rat's mean thoracic circumference, with two pieces of platinum electrodes attached on its inner surface, allowing ECG to be recorded noninvasively in conscious, restrained rats (n=6). Time-and frequency-domain HRV analyses were conducted, under basal and autonomic blockade conditions. High-quality ECG signals were obtained, being feasible for HRV analysis. As expected, mean RR interval was significantly decreased in the presence of atropine (p<0.05) and increased in the presence of propranolol (p<0.001). Also, reinforcing the reliability of the method, low-and high-frequency HRV spectral powers were significantly decreased in the presence of propranolol (p<0.05) and atropine (p<0.001), respectively. In summary, the present work describes a novel, inexpensive and noninvasive method for surface ECG recording in conscious rats.

Computerized electrocardiography in healthy conscious guinea pigs (Cavia porcellus)

“…Anesthetized guinea pig model is effective in early cardiovascular studies to evaluate the effects of drug candidate molecules, but anesthesia has a number of effects on the cardiovascular system and may cause disturbances on the ECG, especially in the QT interval (Hamlin et al 2003, Morissette et al 2013. So, the development and application of a noninvasive method for aquisition of ECG tracings in awake animals may present a consistent alternative approach for long-term studies (Pereira-Júnior et al 2010).…”

Monitoring vital signs over multiplexed radio by near-field coherent sensing

“…Methods based on body electrodes, such as electrocardiograms, require direct skin contact, and for some people, chest hair may need to be removed to improve the signal quality. For animal tests in rats, pigs and monkeys, hair removal or needle electrodes is almost always required, which complicates the preparation steps and adds to animal discomfort 14,15 . Commercial optical absorption methods, such as photoplethysmography, rely on the reflection or transmission of infrared light, which limits sensing depth and leads to loss of waveform detail and timing accuracy 16 .…”

A Tail-Worn Sensor-Equipped Heart Rate Measurement Apparatus for Ischemic Stroke Prevention

“…This is done by means of the intensity of the reflected IR signals from the tail of a rat. The PPG sensors can be placed anywhere due to the fact that there are plenty of micro blood vessels and four major vessels over the tail, meaning that the ECG sensor alignment problem suffered in a conventional body worn device can be completely resolved [23]. As illustrated in Figure 1, a PPG array circuit, composed of three independent extraction circuits, is employed herein to measure PPG signals at various locations followed by corresponding INA333 instrumental amplifiers.…”

“…Up to now, physiological signals are measured in an invasive and a noninvasive manner. In the former case, sensors must be embedded into animals by surgery in advance, which cannot be performed on tiny mice [19][20][21][22], resulting in an increase in the experiment complexity, and rats have the risk of infection as a consequence [23]. Even though invasive measurement apparatus were designed to monitor the physiological conditions of rats in either anesthetized or conscious state with a low physical confinement feature [22], a major disadvantage is the battery capacity limit of a battery powered wireless transmission module, that is, a long-term monitoring is non-feasible.…”

“…Consequently, non-invasive physiological measurements were conducted in two ways. In the first way, measurements were performed on restrained and conscious rats [24][25], while, in the second way, body-worn sensors were employed to eliminate the above-stated physical restraint [23]. However, it is rather difficult to place a sensor precisely onto a specific spot of a A Tail-Worn Sensor-Equipped Heart Rate Measurement Apparatus for Ischemic Stroke Prevention…”