Fig. 4.

Pressure-diameter relationship (PDR) for the myocardium enclosing order 5–7 vessels, in the gap case, with mechanical model curves (mechanical in inset, Appendix B) and sigmoidal models (sigmoid in inset) from Eq. 6. The R² values for the sigmoidal fit to the mechanical model were 0.997, 0.996, and 0.996 for the gap case and 0.996, 0.997, and 0.997 for the no-gap case (not shown) for orders 5, 6, and 7, respectively. An excessively wide pressure range of −500 to +500 mmHg was used simply to demonstrate the sigmoidal shape of the myocardial PDR.