[The pressure-dimension curve and midwall stress. Use of a combined hemodynamic-echocardiographic method and correlation with contrast ventriculography].
An invasive (left ventricular pressure recording) and a noninvasive technique (M-mode echocardiography) were combined during the hemodynamic study of 15 patients with various degrees of left ventricular impairment, in order to provide left ventricular function parameters independent from contrast studies. Left ventricular pressure, dimension and wall thickness changes were continuously digitized on a computer system, which was able to derive the ventricular pressure-dimension loop and to calculate the midwall equatorial stress at end-diastole and peak-systole. The parameters derived from the loop (diastolic work, net systolic work, cycle efficiency) and midwall meridional and circumferential stresses were compared with the results of contrast ventriculography and with the wall hypertrophy index. Diastolic work appeared to be correlated with the systo-diastolic volume change; systolic work correlated with the ejection fraction; the cycle efficiency was inversely correlated with both end-diastolic and end-systolic volumes and directly correlated with the hypertrophy index. Midwall stress, both end-diastolic and peak-systolic, was strongly and positively correlated with ventricular volumes, while it decreased with increasing hypertrophy. Systolic stress increased with decreasing ejection fraction. The combined echo-pressure technique, through the evaluation of the pressure-dimension loop and the calculation of wall stress, can generate data of left ventricular function that allow a more complete assessment of left ventricular impairment.