Use of heart blood flow analysis in clinical practice

Abstract

Often in the treatment of patients echocardiograms are performed to analyse cardiac function. As part of the calculation the shear and normal stress on the endocardial surface of the left ventricle can be calculated. This was undertaken for five elderly women patients undergoing stress testing. It was found that when the stress was plotted as a function of strain rate the expected variation would be a linear increase in stress. In some patients there was initially a sharp increase in stress with strain rate then an abrupt change in the stress at the apex or at the mitral valve annulus. With further increase in strain rate the rate of increase in stress decreased. This would suggest that there was some defect in the wall structure. The variation of ventricular volume with strain rate can be obtained. In this case the volume should decrease initially and as the strain rate increases the volume change becomes less. In two of the five patients the expected initial rise in stress did not occur. This suggests a lack of strength of the ventricle. As expected these were not the same patients where the abrupt increase in stress occurred. Such information may be helpful to a clinician in reaching a diagnosis.