Page 9 - The Mathematic Model - concentric rings
Now a brief word on the properties of concentric rings. This image demonstrates the fact that if you have two concentric rings which maintain the same distance apart when the inner contracts, then the outer can keep pace with the inner with a lesser degree of shortening.
Follow the red arrows in this image. On the left, an inner ring of 5.8cm diameter, whose circumference shortens by 15%, is matched by an outer ring 4mm distant (i.e. a diameter of 6.6cm). On the right, when the inner ring has shortened its circumference by 15%, the outer has only had to shorten by 13% to keep pace.
In life, if these rings were the mid-wall and outer rings of the left ventricle, the gap between the two would increase as the wall thickens, and the outer would have to contract even less. The models will try to quantify this.