Use of Implantable Loop Recorders to Monitor for Cardiac Disease in Captive Gorillas (Gorilla gorilla gorilla)
Cardiac disease is the leading cause of death in captive male western lowland gorillas (Gorilla gorilla), accounting for nearly 45.7% of deaths in this population.2 Implantable loop recorders (ILRs) are valuable for monitoring cardiac disease in humans and have been used in chimpanzees.1 They provide a continuous electrocardiogram (ECG) trace, detect cardiac arrhythmias, and measure daytime and nighttime heart rate (DHR, NHR) and heart rate variability (HRV). In this study, Reveal XT ILRs were placed in three male gorillas, 13–15 years of age; implants were interrogated biweekly, and data was analyzed for a two-year period. One gorilla had an average DHR of 65 bpm, an average NHR of 49 bpm, and HRV of 207. This individual was being treated with lisinopril and carvedilol during the study period and had four episodes of early-morning bradycardia (HR <30 bpm). The remaining two gorillas had average DHR of 74±1.0 bpm and average NHR of 65±1.0 bpm, with HRV of 99 and 108. One of these received the same medications during the study period, and the other had regular episodes of supraventricular tachycardia, with rates around 188 bpm. There are three male gorillas from other institutions that have had ILRs for variable periods. Two of these, ages 10 and 13 y, had lower average DHR (40, 54 bpm) and NHR (47, 51 bpm) and higher heart rate variability (223, 139). A 27-year-old male had an average DHR of 39 bpm and NHR of 33 with HRV of 284.
The authors thank the Great Ape Heart Project for their support of the comprehensive study of heart disease in great apes. In addition, the authors also thank the Primate Staff at the Detroit Zoo, for their commitment to training great apes for these and other veterinary procedures. Thanks also go to the veterinary team at the Detroit Zoo.
1. Lammey ML, Jackson R, Ely JJ, Lee DR, Sleeper MM. Use of an implantable loop recorder in the investigation of arrhythmias in adult captive chimpanzees (Pan troglodytes). Comp Med. 2011;61:71–75.
2. Meehan T. Personal communication.