| Summary: | Objective: Non invasive methods have been proposed to assess end systolic left ventricular (LV) elastance (Ees), but clinical application remains complex. The aim of the present study was to 1) estimate Ees according to modeling of LV pressure-volume (P-V) curve during ejection and validate our method with existing published LV P-V loop data 2) test clinical applicability to detect a difference in Ees between normotensive and hypertensive subjects.
Methods: Based on P-V curve and a linear relationship between LV elastance and time during ejection, we fitted the systolic pressure curve (non linear least square method). We then computed slope and intercept of time varying elastance, and calculated Ees as LV elastance at the end of ejection. As a validation, 22 P-V loops obtained from previous invasive studies were digitized and analyzed with our method. To test clinical applicability, P-V curve was obtained from 32 normotensive and 33 hypertensive subjects, using carotid tonometry and real-time 3D echocardiography.
Results: A strong univariate relationship (r2=0.92, p<0.005) and good limits of agreement were found between previous invasive measurement of Ees and our new proposed Ejection P-V Curve method. In hypertensives, when compared to normotensives, the increase in arterial elastance (Ea, 1.83±0.80 vs 1.45±0.41 mmHg/mL, p<0.001) was compensated by an increase in Ees (2.65±1.07 vs 1.88±0.54 mmHg/mL, p<0.001) without change in Ea/Ees (0.76±0.19 vs 0.85±0.23, p=0.09).
Conclusions: Ees can be estimated non invasively from modeling of P-V curve during ejection. This approach was found sensitive enough to detect an expected difference in LV contractility in hypertensive patients.
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