Concomitant changes in regional myocardial deformation and intraventricular pressure gradients in normal and sedated...

The intraventricular pressure gradient (IVPG) measured by color M-mode echocardiography (CMME) and two-dimensional speckle tracking echocardiography (2D-STE) have emerged as novel imaging techniques for heart function evaluation. Various experimental and clinical studies have been conducted on animals, but reports on ruminant species are limited.

This study aimed to determine the concomitant changes in IVPG and 2D-STE in goats before and after sedation and highlight the relationship between the parameters obtained from the two imaging techniques.

Ten male goats were included and the full conventional echocardiographic protocol, including 2D, M-mode, spectral Doppler, tissue Doppler imaging (TDI), 2D-STE, and CMME were performed before and after sedation with xylazine (50 ug /kg BW/IM). The analysis of 2D-STE at the apical and mid-levels of the left ventricle and the IVPG were assessed using special software.

The results showed good quality data obtained for the evaluation of heart functions through conventional echocardiography, CMME, and 2D-STE. Xylazine administration significantly reduces mitral inflow and TDI velocities as well as the total IVPG and basal IVPG. (P < 0.05). Sedation also significantly disturbed the contractility of the segmental myocardium at the mid and apical levels. The radial and circumferential strains and strain rates, in addition to the synchrony time index, were reduced accordingly (p < 0.05).

This study utilizes two novel imaging techniques to assess changes observed in cardiac function in goats after sedation. Xylazine, an α2-agonist, induces loading alterations that disproportionately affect wall mechanics, reducing circumferential and radial shortening as well as IVPG parameters. Our findings confirm that CMME and 2D-STE are sensitive tools to detect subtle, region-specific alterations in the IVPG and myocardial function, respectively, in ruminants, complementing conventional echocardiographic indices. This may have important implications for both clinical monitoring and experimental designs where α₂-adrenergic agonists are employed.