P785Noninvasive quantification of left ventricular elastance and ventricular-arterial coupling using three-dimensional echocardiography and arterial tonometry

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Techniques previously used to assess left ventricular (LV) elastance (Ees) and ventricular-arterial coupling (CLV-A) relied on invasive measurements and data acquisition over a wide range of loading conditions. Our goals were to assess the feasibility of noninvasive assessment of Ees and CLV-A using the combination of real-time three-dimensional echocardiography (RT3DE) and arterial tonometry, to test the ability of this approach to detect changes in LV contractility and its reproducibility.Methods: We studied pharmacologically induced changes in inotropic state (10 μg/kg/min dobutamine) in normal volunteers (N=8), and compared 10 normal subjects with 10 patients with dilated cardiomyopathy (DCM; EF<35%). Full-volume RT3DE imaging of the left ventricle, calibrated carotid artery tonometry and Doppler tracings were acquired to noninvasively estimate Ees and CLV-A. Reproducibility was assessed by repeated measurements.Results: Dobutamine caused a significant increased blood pressure, heart rate, EF and Ees and a decreased CLV-A. In patients with DCM, Ees was significantly reduced and CLV-A elevated, compared to controls. Both inter- and intra-observer variability were good for all measured parameters, as reflected by intra-class correlation coefficients (ICC >0.8) and coefficients of variation (CV<20%). Calculated Ees showed significant differences between DCM patients and controls, with no overlap and good reproducibility: inter-observer ICC 0.83, CV 20%.Conclusions: This is the first study to test the feasibility of using RT3DE-derived instantaneous LV volumes in conjunction with arterial tonometry to noninvasively quantify LV elastance and LV-arterial coupling without the need to alter the loading conditions. This approach is reproducible and able to detect changes in LV contractility.

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