Abstract
Abstract Background Cardiac shear wave elastography (SWE) allows for the non-invasive assessment of myocardial stiffness via the detection of shear waves (SW) travelling through the heart after e.g. mitral valve closure (MVC). The propagation speed of these waves is directly related to myocardial stiffness. Myocardial operational stiffness depends on the intrinsic properties of the myocardium as well as the loading conditions of the heart. Therefore, changing loading conditions, for example volume unloading under diuretics, could influence SW speed. Purpose To evaluate the effect of volume unloading on shear wave speed in patients with decompensated heart failure before and after intravenous diuretics. Methods Eleven patients with decompensated heart failure were included. SWE was performed in the first hours after they presented at the emergency room and a few days later before discharge of the hospital. In between, all patients had received intravenous diuretics. For SWE, tissue doppler imaging of the LV parasternal long axis view was acquired at a high frame rate (1048±97 fps) using a research ultrasound scanner. SWs after mitral valve closure were visualized in M-modes of the septum, colour coded for tissue acceleration (fig A). The slope of the shear waves in the M-mode represents their propagation speed. SW speeds were measured in a semi-automatic manner. Results Patient characteristics are described in table 1. There was a significant decrease in weight (80.6±17.6kg vs 76.7±15.9kg, p<0.001) and tricuspid regurgitant velocity (3.4±0.5m/s vs 2.8±0.7m/s) before discharge, indicating a decrease in volume overload. Ejection fraction, global longitudinal strain and E/e’ did not significantly change between admittance and discharge. E/A ratio is not described, as most patients had atrial fibrillation. SW speed was significantly higher in the decompensated state upon admission than right before discharge (7.3±1.8m/s vs 5.4±1.4m/s, p<0.001; Fig B). A borderline correlation was observed between the difference in shear wave speed and weight loss between admission and discharge (r=0.53; p=0.09; Fig C). Although this was not significant, likely due to the limited size of the study population, it seems that SW speed decreases with decreasing volume overload. Furthermore, a borderline correlation was seen between shear wave speed and pro-BNP at admittance (r=0.60; p=0.085; Fig D), possibly indicating that there is a link between increased shear wave speed and increased filling pressures. Conclusion SW speed at mitral valve closure significantly decreased with decreasing volume overload in patients with decompensated heart failure. We hypothesize, that unloading the LV causes a leftward shift on the end-diastolic pressure-volume-relation and with this a decrease in in end-diastolic myocardial stiffness. SWE might become an interesting tool to non-invasively evaluate diastolic properties of the LV. Table 1 Figure 1
Published Version
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