Toward a new method of analyzing cardiac performance

Aside from the traditional diagnostic tools used to assess cardiac performance, such as blood pressure and cardiac output, cardiac source parameters can also be used as an indication of overall cardiac health. The cardiac source parameters under investigation are myocardial visco-elastic properties. The objective of this study is to model the left ventricle using electrical circuits, then use these models to estimate the cardiac source parameters. Two electrical models of the left ventricle have been developed, using a resistor (R) to model viscous losses, a capacitor (C) to represent inverse elastance, and a time-varying pressure source, which models the left ventricular pressure during an isovolumic beat. One model uses a single resistor and the other uses the two elements (R and C) in parallel. The differential equations describing these models have been derived, and a minimization procedure was used to adjust values of R and C in the differential equations until a good agreement between experimental and calculated left ventricular pressure was reached. Preliminary results indicate that the model including a parallel combination of R and C provides a better fit between experimental and calculated pressures. It is hoped that these parameters may one day provide clinicians with yet another diagnostic tool to help discover the source of cardiac disorders.