STRUCTURAL BASIS OF VENTRICULAR STIFFNESS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 44  (1) , 49-54
Abstract
The morphologic component of ventricular stiffness was not clearly delineated. This stiffness factor varies over wide ranges with the degree of distension being very low at low volumes and very high at high volumes. It is constant in rats and hamsters from 30 days of age to 17 mo., varying no more than 20%, with increases in mass of 4 fold. These parameters alone suggest a complex structure or structures. The ventricular stiffness factor of rats is about twice that of hamsters at all ages. This naturally occurring variation in stiffness of normal hearts from the 2 species provides an excellent model to examine for morphologic differences that might explain the variation in stiffness of the 2 ventricles. Hearts from each species from 1-7 mo. of age were examined by light microscopy and scanning and transmission electron microscopy. There is a major difference between the 2 species in the amount of collagen in the form of 120 to 150 nm diameter bundles that form a weave around groups of myocytes. This system is far more extensive in rats than hamsters and is the only morphologic difference that can easily explain the divergence in stiffness between the 2 species.