Instantaneous end diastolic stiffness (IEDS): a simple, load independent measurement of left ventricular diastolic...

The end-diastolic pressure-volume relation is a load-independent measurement of diastolic function. However, its clinical utility is limited because of its complexity. Instantaneous end-diastolic stiffness (IEDS) is a simple to perform, single-point, measurement of ventricular stiffness. We have validated it against the end-diastolic pressure-area relation (EDPAR) in patients undergoing cardiac surgery. EDPARs were analyzed before and after cardiopulmonary bypass in 29 patients and compared with IEDS. Data was collected in an additional 69 patients in order to estimate the range of values of IEDS. End-diastolic area (EDA) measured by transesophageal echocardiography (TEE) was substituted for end-diastolic volume, and pulmonary capillary wedge pressure (PWCP) was substituted for end-diastolic pressure. IEDS = 100 x (log10 PWCP)/EDA. Comparison of the methods was done by ordinary least products regression analysis. Agreement between EDPAR and IEDS was identified by the absence of fixed and proportional bias. The maximal range of corresponding values identified by 95% confidence intervals was within +/- 16% of the mean indicating satisfactory agreement. The geometric mean and 95% confidence intervals (CI) for IEDS were 8. 7 mmHg/dm2 (8.1 to 9.4) and for IEDS indexed to body surface area were 17.2 mmHg/dm(2)/m2 (16.0 to 18.6). IEDS is a load independent index of left ventricular stiffness.