Avaliação morfológica e elétrica do coração de Bradypus variegatus Schinz, 1825 (Mammalia: Pilosa)

Abstract

Sloths of the genus Bradypus have been suffering considerably from anthropic pressure, which highlights the importance of knowing the peculiarities of these animals. Therefore, a detailed analysis of the heart of the species Bradypus variegatus was performed. To identify the macroscopic, topographic, biometric and vascular characteristics of the organ, dissections and measurements of 15 cadavers and digital chest radiographs of four healthy animals were performed. In order to clearly observe the coronary profile of B. variegatus, three specimens received an arterial injection of latex with red pigment, and in one of them, an intravenous injection, in blue, was also performed. For the microscopic description, the hearts of four specimens were used. Organs were fixed in 10% buffered formaldehyde with 0.01M sodium phosphate buffer (PBS) at pH 7.3 and subjected to paraffin embedding processing, followed by 4μm thick sagittal sections stained in hematoxylin-eosin. Electrocardiographic profiles of five sloth animals in good health were also obtained. In view of the collected results, the heart of the species in question is conical, located obliquely in the middle mediastinum, displaced to the left, presenting varied skeletonpies. The organ is covered by the pericardium and the atria are internally, predominantly smooth, while pectineal muscles are seen in the atria. The ventricles have fleshy trabeculae and papillary muscles, from which tendinous chords depart, which attach to the valves. Two coronary arteries, one right and one left, were described. According to the histopathological findings, necrosis of different cell types was seen in the hearts. Endocardiosis and inflammatory and degenerative, processes have also been described, with a lower prevalence. Based on electrocardiographic recordings, sloth animals demonstrated sinus rhythm, with heart rate between 67 and 100bpm. In general, the heart of B. variegatus does not show large discrepancies in relation to other quadrupeds.