RAPID ESTIMATION OF LEFT-VENTRICULAR CONTRACTILITY FROM END-SYSTOLIC RELATIONS BY ECHOCARDIOGRAPHIC AUTOMATED BORDER DETECTION AND FEMORAL ARTERIAL-PRESSURE

Background: Automated echocardiographic measures of left ventricular ( LV) cavity area are closely correlated with changes in volume and can be coupled with LV pressure to construct pressure-area loops in real t ime. The objective was to rapidly estimate LV contractility from the e nd-systolic relations of cavity area (as a surrogate for LV volume) an d femoral arterial pressure (as a surrogate for LV pressure) in patien ts undergoing cardiac surgery. Methods: Studies were attempted on 18 c onsecutive patients with recordings of LV pressure, LV area, and femor al arterial pressure on a computer workstation interfaced with the ult rasound system. End-systolic pressure-area relations (in terms of pres sure-area elastance [E'(es)]) from pressure-area loops during inferior vena caval occlusions were determined before and immediately after ca rdiopulmonary bypass using both LV and arterial pressure by semiautoma ted and automated iterative linear regression methods. Results: Data s ets were available for 13 patients before and 8 patients after bypass (21 studies in 14 patients). E'(es) by arterial pressure was closely c orrelated with E'(es) by LV pressure: r = 0.96, standard error of the estimate = 2 mmHg/cm(2), y = 1.01 X -0.7 by the semiautomated method a nd r = 0.94, standard error of the estimate = 3 mmHg/cm(2), y = 1.02 X -0.5 by the automated method. Analysis of semiautomated and automated estimates of E'(es) from arterial pressure and E'(es) using LV pressu re by the Bland-Altman method showed no systematic measurement bias an d calculated limits of agreement of 8 and 9 mmHg/cm(2), respectively. Similar decreases in E'(es) by arterial and LV pressure occurred from before to after bypass in 7 patients with paired data sets: 32 +/- 12 to 15 +/- 6 mmHg/cm(2) and 32 +/- 15 to 15 +/- 7 mmHg/cm(2), respectiv ely (P < 0.05 for both). Conclusions: On-line femoral arterial pressur e and LV area data by echocardiographic automated border detection may be used to rapidly calculate E'(es) as a means to estimate LV contrac tility in selected patients.