The influence of age and sex upon cardiac structure and function in wild-born captive chimpanzees (Pan troglodytes)

Objective – To comprehensively characterise cardiac structure and function, from infancy to adulthood, in male and female wild-born sanctuary living chimpanzees (Pan troglodytes). Animals – 290 chimpanzees, 149 females and 141 males. Procedures – Structural and functional cardiac data from 290 chimpanzees were collected using echocardiography between October 2013 and May 2017 in three African chimpanzee sanctuaries. A comprehensive characterisation of the normal cardiac phenotype is presented for both sexes across four age groups; infants, juveniles, sub-adults and adults. Age group and sex differences were explored via multiple one-way independent Kruskal-Wallis tests. Results – Sub-adult and adult male chimpanzees had larger cardiac wall dimensions and volumes than their female counterparts. Both males and females demonstrate an age-related decline in left ventricular diastolic and systolic function, yet these reductions were noted earlier in males than females. Right ventricular diastolic function was not different with age; in contrast, systolic function was lower in adult chimpanzees compared to young and juvenile animals as measured by right ventricular fractional area change. Conclusions and Clinical Relevance – Echocardiography is widely used for the assessment of cardiac structure and function in chimpanzees, yet, the normal cardiac phenotype, until now, has not been appropriately defined. This study provides comprehensive echocardiographic data from a large population of wild-born sanctuary captive chimpanzees, whereby reference intervals will aid clinicians caring for this endangered species.