311 A new color Doppler-based echocardiographic technique for evaluation of intraventricular flow dynamics: first application to normal subjects, athletes, and patients

Abstract

Aims A new echocardiographic, color Doppler-based technique, named HyperDoppler, has been recently introduced for non-invasive evaluation of intracardiac flow dynamics. The aim of this study was to verify the feasibility and reproducibility of this technique and its capability to differentiate geometrical and energy measures of vortex flow within the left ventricle (LV) in normal subjects, athletes and patients with heart failure. Methods and results Two Italian cardiology centres enrolled each one 100 unselected, consecutive patients presenting at the echocardiography laboratory for a clinical examination, regardless of the indication to echocardiography. In these patients, the feasibility, repeatability, reproducibility, and inter-centre reproducibility of the HyperDoppler technique were tested using the intraclass correlation coefficient (ICC) and Bland–Altman analysis. In addition, 50 normal subjects, 30 professional athletes, and 50 patients with stabilized chronic heart failure and LV ejection fraction <40% were enrolled. Images were acquired using a MyLab X8 echo-scanner and analysed to provide the following vortex flow measures: vortex area, normalized with the LV area; vortex intensity (i.e. the integral of the vorticity inside the vortex), normalized with the total vorticity; vortex depth (the distance of its centre from the LV base) and length along the base-apex direction, both normalized with the LV length; and the total kinetic energy dissipation (KED). Feasibility of HyperDoppler was very high (94.5%). According to the ICC values, at Centre 1 repeatability and reproducibility of vortex flow measures in unselected patients were good for vortex area (0.82, 0.85), length (0.83, 0.82) and depth (0.87, 0.84) and excellent for vortex intensity (0.92, 0.90) and KED (0.98, 0.98). Results of the Bland–Altman analysis showed no bias nor consistent under/overestimations of flow measures, with 95% of points always lying within the limits of agreement for each flow measure. Centre 2 provided similar repeatability and reproducibility evaluations for all the vortex measures, thus supporting a good-to-excellent inter-centre reproducibility. Athletes had greater vortex area, intensity, and KED compared to healthy subjects while they had smaller vortex length and depth and greater KED compared to patients with heart failure and reduced LV ejection fraction. In comparison with healthy subjects, heart failure patients showed greater vortex area, length, depth, and intensity but smaller KED. Combining vortex flow measures, the LV flow profile of healthy individuals, athletes, and heart failure patients could be differentiated. Conclusions HyperDoppler is a new ultrasound technique which is feasible, reliable, and practical for assessment of LV flow dynamics. It can quantitate several measures of the LV vortex and may distinguish normal subjects and patients. Future studies are needed to clarify how to implement this technique in cardiology clinical practice.