An integrated model of LV muscle mechanics, coronary flow, and fluid and mass transport.

An integrated left ventricular (LV) model that accounts for the three-phase (fiber-blood-interstitium) myocardial structure and composition is used to study the interactions among myocardial mechanics, coronary flow, and fluid and mass transport. Effects of ventricular load, coronary perfusion pressure, and fluid and mass transport on ventricular performance and coronary dynamics are studied here. In agreement with experimental observations, the analysis shows that 1) coronary flow impediment is not significantly affected by changes in the afterload and preload at constant coronary perfusion pressures, 2) an increase in coronary perfusion pressure increases the intramyocardial pressure (IMP) as well as the mean flow and oscillatory flow amplitude, 3) contractility has a direct effect on IMP and coronary flow impediment, and 4) changes in blood osmolarity and lymphatic outflow, which may cause myocardial edema, affect both ventricular mechanics and coronary flow. Clearly, accounting for fluid and mass transport allows to study the interactions among coronary flow, ventricular and myocardial mechanics, and intramyocardial fluid shifts.