Chordae Tendineae Architecture in the Papillary Muscle Insertion

Chordae tendineae architecture and their junction with papillary muscle were studied with scanning electron microscopy, comparing human and swine hearts.Papillary muscles with the corresponding chordae tendineae were obtained from human and pig ( Sus scrofa) hearts after exposition of the left ventricle cavity, fixed with 4% formaldehyde.The specimens were sectioned in small samples and divided in four groups, a control one and the others submitted to digestion in a solution of 2.5% sodium hypochlorite in saline solution during 5, 10 and 15 minutes respectively.The specimens were washed and fixed in 1% osmium tetroxide in cacodylate buffer, kept in 1% tannic acid for 30 minutes, dehydrated and critical point dried, mounted and sputtered with gold.The specimens were examined and documented in a JEOL 5200 scanning electron microscope.The human and swine chordae tendineae have similar architecture: both are covered by the endothelium which was in continuity with the papillary muscles, the inner layers are composed by longitudinal and oblique collagen bundles intermingled with elastic fibers.Differences between swine and human hearts were found in the chordae tendineaepapillary muscle junction.In the human heart the collagen bundles showed a more organized arrangement, forming a meshwork with the fibers disposed in approximately orthogonal angles, whereas in the swine heart the fibers were randomly disposed.