Flow-volume loops derived from three-dimensional echocardiography: a novel approach to the assessment of left ventricular hemodynamics

BACKGROUND: This study explores the feasibility of non-invasive evaluation of left ventricular (LV) flow-volume dynamics using 3-dimensional (3D) echocardiography, and the capacity of such an approach to identify altered LV hemodynamic states caused by valvular abnormalities. METHODS: Thirty-one patients with moderate-severe aortic (AS) and mitral (MS) stenoses (21 and 10 patients, respectively) and 10 healthy volunteers underwent 3D echocardiography with full volume acquisition using Philips Sonos 7500 equipment. The digital 3D data were post- processed using TomTec software. LV flow-volume loops were subsequently constructed for each subject by plotting instantaneous LV volume data sampled throughout the cardiac cycle vs. their first derivative representing LV flow. After correction for body surface area, an average flow-volume loop was calculated for each subject group. RESULTS: Flow-volume loops were obtainable in all subjects, except 3 patients with AS. The flow-volume diagrams displayed clear differences in the form and position of the loops between normal individuals and the respective patient groups. In patients with AS, an "obstructive" pattern was observed, with lower flow values during early systole and larger end-systolic volume. On the other hand, patients with MS displayed a "restrictive" flow-volume pattern, with reduced diastolic filling and smaller end-diastolic volume. CONCLUSION: Non-invasive evaluation of LV flow-volume dynamics using 3D-echocardiographic data is technically possible and the approach has a capacity to identify certain specific types of alteration of LV flow-volume pattern caused by valvular abnormalities, thus reflecting underlying hemodynamic states specific for these abnormalities.