Endocardial Fibroelastosis of Large Mammals
Normal hearts of a mouse, rat, man, sea lion, hippopotamus, elephant, and blue whale were shown to have different numbers of myocardial fibers, 107 to 1013, based on calculations involving their myocardial fiber diameters and nuclear density counts. These two parameters did not vary greatly in the different species. However, their heart weights ranged from 10-1 to 105 g. The larger mammals have endocardial fibroelastosis of their hearts and very thick aortas. These anatomic findings were explained by employing principles of hydrostatics and proposing that elastic tissue is required to help withstand the high mural tension resulting from the long radii and the hydrostatic pressures in the heart chambers and aortic lumen.
- Accepted October 13, 1964.
- © 1965 American Heart Association, Inc.