Standard Electrocardiographic Data of Young Japanese Monkeys (Macaca fusucata)

The electrocardiogram of nonhuman primates is similar to that of humans because of similar intrathoracic heart position and structure. Despite the frequent use of nonhuman primates in biologic studies, few electrocardiographic studies of Japanese monkeys (Macaca fusucata) have been reported, and no reference data are available for this species. We obtained limb-lead electrocardiograms from indoor-bred and housed ketamine-sedated Japanese macaques (48 male; 56 female; mean age, 44.3 mo; mean body weight, 4.84 kg) in the dorsal recumbency. The following quantitative data was obtained: heart rate, P wave amplitude and width, R wave amplitude, QRS duration, PR interval, QT interval, T wave height, and mean electrical axis. Corrected QT intervals were calculated by using the Bazett and Fridericia formulae. Measurements were evaluated according to sex and age. The duration of the QRS complex showed moderate correlation with age in male monkeys. All parameters, except heart rate, were similar to previous reports from Japanese, cynomolgus, and other macaques. P waves, R waves and mean electrical axis did not differ significantly between humans and Japanese macaques, but the wave amplitude in macaques was half that in humans. Our electrocardiographic measurements can serve as normal reference data for sedated, young Japanese monkeys.