Non-invasive measurement of volume-time curves in patients with mitral regurgitation and in healthy volunteers, using a new operator-independent screening tool

Abstract

Left ventricular volume-time curves (VTCs) provide hemodynamic data, and may help clinical decision making. The generation of VTCs using echocardiography, however, is time-consuming and prone to inter-operator variability. In this study, we used a new non-invasive, operator-independent technique, the hemodynamic cardiac profiler (HCP), to generate VTCs. The HCP, which uses a low-intensity, patient-safe, high-frequency applied AC current, and 12 standard ECG electrodes attached on the thorax in a pre-defined pattern, was applied to five young healthy volunteers, five older healthy volunteers, and five patients with severe mitral regurgitation. From the VTCs generated by the HCP, the presence or absence of an isovolumetric contraction phase (ICP) was assessed, as well as the left ventricular ejection time (LVET), time of the pre-ejection period (tPEP), and ratio of the volumes of the early (E) and late (A) diastolic filling (E V/A V ratio), and compared to 2D transthoracic echocardiography (2D TTE) at rest. The reproducibility by two different operators showed good results (RMS = 5.2%). For intra-patient measurement RMS was 2.8%. Both LVET and the E V/A V ratio showed a strong significant correlation between HCP and 2D TTE derived parameters (p < 0.05). For tPEP, the correlation was still weak (p = 0.32). In all five patients with mitral regurgitation, the ICP was absent in the VTC from the HCP, whereas it was present in the 10 healthy volunteers, which is in accordance with pathophysiology. We conclude that the HCP seems to be a method for reproducible VTC generation, and may become a useful early screening tool for cardiac dysfunction in the future.