Discovery of os cordis in the cardiac skeleton of chimpanzees (Pan troglodytes)

Abstract

Cardiovascular diseases, especially idiopathic myocardial fibrosis, is one of the most significant causes of morbidity and mortality in captive great apes. This study compared the structure and morphology of 16 hearts from chimpanzees (Pan troglodytes) which were either healthy or affected by myocardial fibrosis using X-ray microtomography. In four hearts, a single, hyperdense structure was detected within the right fibrous trigone of the cardiac skeleton. High resolution scans and histopathology revealed trabecular bones in two cases, hyaline cartilage in another case and a focus of mineralised fibro-cartilaginous metaplasia with endochondral ossification in the last case. Four other animals presented with multiple foci of ectopic calcification within the walls of the great vessels. All hearts affected by marked myocardial fibrosis presented with bone or cartilage formation, and increased collagen levels in tissues adjacent to the bone/cartilage, while unaffected hearts did not present with os cordis or cartilago cordis. The presence of an os cordis has been described in some ruminants, camelids, and otters, but never in great apes. This novel research indicates that an os cordis and cartilago cordis is present in some chimpanzees, particularly those affected by myocardial fibrosis, and could influence the risk of cardiac arrhythmias and sudden death.

Ventricular Septation and Outflow Tract Development in Crocodilians Result in Two Aortas with Bicuspid Semilunar Valves

“…In adult otters [45] and various ungulates such as buffalo [46], white rhinoceros [47] and sheep [48], a "heart bone" is present in the fibrous trigone between left AV canal and aorta. A subgroup of diseased chimpanzees with myocardial fibrosis presented with trabecular bone or hyaline cartilage in the right fibrous trigone [49]. In (sub)adult alligators, a cartilage crown is present, nearly completely encircling the roots of both aortas [50,51], but penetrating not as deep into the ventricle as described by us.…”

Ventricular Septation and Outflow Tract Development in Crocodilians Result in Two Aortas With Bicuspid Semilunar Valves

“…In adult otters [46] and various ungulates such as buffalo [47], white rhinoceros [48] and sheep [49], a 'heart bone' is present in the fibrous trigone between left AV canal and aorta. A + subgroup of diseased chimpanzees with myocardial fibrosis presented with trabecular bone or hyaline cartilage in the right fibrous trigone [50]. In (sub)adult alligators a cartilage crown is present nearly completely encircling the roots of both aortas [20,51]), but penetrating not as deep into the ventricle as described by us.…”

Anatomical features of ossa cordis in the Steller sea lion

“…In the present study, pathological changes were not observed in the ossa cordis/cartilage cordis. Previous reports on the ossa cordis in chimpanzees revealed that its formation was related to pathological changes [ 14 ]. In this case, an increased collagen level was observed, which was adjacent to the ossa cordis/cartilage cordis.…”

“…[ 3 ] proposed new functions of the cartilaginous foci in Syrian hamster hearts as pivots resisting the mechanical tensions of cardiac motion. However, it was reported that heart disease may also be associated with the development of ossa cordis, as observed for idiopathic myocardial fibrosis in chimpanzees [ 14 ]. Marine mammals include nonlanding species (i.e., cetaceans) and landing species (i.e., pinnipeds), and their cardiac workloads may be different.…”