Use of two-dimensional speckle tracking echocardiography to assess left ventricular systolic function in dogs with systemic inflammatory response syndrome

SIRS is a clinical syndrome caused by systemic inflammation of infectious or non-infectious origin. SIRS is characterized by an endogenous cascade of interleukins and others inflammatory mediators such as TNF-α IL-6 and IL-1 which are responsible to the myocardial depression during systemic inflammation. Conventional echocardiographic indices of LV systolic function such as Fractional Shortening (FS%) and Ejection Fraction (EF%) are not sensitive enough to detect mild or early systolic dysfunction in dogs suffering from SIRS. Speckle-Tracking Echocardiography (STE) is a new echocardiographic technique that allows an objective and quantitative evaluation of global and regional myocardial function through the analysis of the motion of speckles that are created by the interaction of ultrasonic beams and the myocardium during the 2D exam. In the present study we tested the hypothesis that 2D-STE may detect LV systolic dysfunction, not diagnosed by conventional echocardiography, in dogs with SIRS. 17 dogs with evidence of SIRS and 17 healthy dogs as a control group were included in this prospective study. At the time of Veterinary Teaching Hospital admission each dog was submitted to standard 2D, M-mode, Doppler and 2D Speckle Tracking echocardiography to assess systolic function. Furthermore, blood samples were obtained for the measurements of cTnI and CRP serum levels. To assess the intraobserver within-day and between-day variability of the 2D-STE acquisition and measurements we performed a study of variability on 5 healthy dogs belonging to the control group. The results showed that the 2D-STE had low intraobserver variability and that the LV Global Longitudinal Peak Strain of endomyocardial layer (ENDO GLPS) and the STE-derived Ejection Fraction (EF%) were lower in the SIRS group than in the control group. On the contrary, standard 2D and M-Mode indices of systolic function such as EF%, FS% weren’t significantly different between the two groups. We didn’t find significant correlation between CRP serum levels and 2D-STE variables and between cTnI and ENDO GLPS. Our study demonstrated that 2D-STE was more sensitive than standard echocardiography in detecting early or mild to moderate myocardial dysfunction, not detected by conventional echocardiography, in a population of dogs with SIRS.