Relationship between chamber mechanical properties and mean pressure-mean flow diagram of the left ventricle

We undertook a theoretical analysis of the source resistance of the left ventricle represented in a mean pressure-mean flow \(\left( {\bar P - \bar Q} \right)\) diagram, using the chamber properties established in terms of the pressure-volume relationship. This analysis showed that \(\bar P - \bar Q\) pairs of points should lie above the linear function proposed by Elzinga and Westerhof. A third-order polynomial function would theoretically explain better than a linear relation or a parabolic fit the curved shape of experimentally obtained \(\bar P - \bar Q\) relationships. The analysis resolves the discrepancy between Elzinga and Westerhof's theoretical concept of linear source resistance and the actual nonlinear \(\bar P - \bar Q\) relationship.