Demographic and Methodological Heterogeneity in Electrocardiogram Signals From Guinea Pigs

Abstract

Electrocardiograms (ECG) are universally used to measure the electrical activity of the heart; however, variations in recording techniques and/or subject demographics can affect ECG interpretation. In this study, we investigated variables that are likely to influence ECG metric measurements in cardiovascular research, including recording technique, use of anesthesia, and animal model characteristics. Awake limb lead ECG recordings were collected in vivo from adult guinea pigs using a platform ECG system, while recordings in anesthetized animals were performed using both a platform and needle ECG system. We report significant heterogeneities in ECG metric values that are attributed to methodological differences (e.g., ECG lead configuration, ECG recording platform, presence or absence of anesthesia) that persist even within the same cohort of animals. Further, we report that variability in animal demographics is preserved in vivo ECG recordings—with animal age serving as a significant contributor, while sex-specific influences were less pronounced. Methodological approaches and subject demographics should be fully considered when interpreting ECG values in animal models, comparing datasets between studies, or developing artificial intelligence algorithms that utilize an ECG database.

Electroanatomical Adaptations in the Guinea Pig Heart from Neonatal to Adulthood

“…Both human 5,34 and guinea pig 24,25 studies have reported an age-dependent effect on ECG parameters. Although, to date, preclinical studies have largely been limited to adults – with no comparison between pediatric and adult guinea pigs.…”

“…ECG recordings were performed as previously described 24,25 . Briefly, animals were anesthetized with 2–3% isoflurane for 10 minutes.…”

“…In vivo ECG ECG recordings were performed as previously described 24,25 27 ), and Tpeak -Tend) were calculated.…”

Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals

“…Nontelemetric approaches have been developed for ECG recordings in conscious, unrestrained animals using a footpad-based system in which animals are placed on a platform containing footpad electrodes that facilitate the acquisition of ECG signals via the paws ( 211 , 216 , 217 ). These systems can be used with a number of animal models (e.g., mice, rats, guinea pigs) as long as the platform is large enough and the footpad electrodes can be properly spaced to accommodate animals of different sizes.…”

“…However, the variable signal-to-noise ratio associated with conscious recordings can limit analysis to heart rate or HRV measurements, as these parameters are only dependent on the detection of prominent R waves. ECG recordings with superior signal quality can be recorded in anesthetized animals using either a footpad or subcutaneous needle electrodes ( 90 , 216 ). For the latter, electrodes are typically positioned for lead I (right and left forelimb) and/or lead II (right forelimb, left hindlimb).…”