Myocardial oxygenation in isolated hearts predicted by an anatomically realistic microvascular transport model

Departments of 1 Bioengineering, 2 Pediatrics, 3 Anesthesiology, and 4 Physiology and Biophysics, University of Washington, Seattle 98194; and 5 Children's Hospital and Regional Medical Center, Seattle, Washington 98105 Submitted 24 April 2003 ; accepted in final form 14 July 2003 An anatomically realistic model for oxygen transport in cardiac tissue is introduced for analyzing data measured from isolated perfused guinea pig hearts. The model is constructed to match the microvascular anatomy of cardiac tissue based on available morphometric data. Transport in the three-dimensional system (divided into distinct microvascular, interstitial, and parenchymal spaces) is simulated. The model is used to interpret experimental data on mean cardiac tissue myoglobin saturation and to reveal differences in tissue oxygenation between buffer-perfused and red blood cell-perfused isolated hearts. Interpretation of measured mean myoglobin saturation is strongly dependent on the oxygen content of the perfusate (e.g., red blood cell-containing vs. cell-free perfusate). Model calculations match experimental values of mean tissue myoglobin saturation, measured mean myoglobin, and venous oxygen tension and can be used to predict distributions of intracellular oxygen tension. Calculations reveal that 20% of the tissue is hypoxic with an oxygen tension of