Quantitative Analysis of Stress Echocardiograms in Healthy Horses with 2-Dimensional (2D) Echocardiography, Anatomical M-Mode, Tissue Doppler Imaging, and 2D Speckle Tracking

Abstract

Background: Stress echocardiography is used to diagnose myocardial dysfunction in horses, but current methods are not well standardized. The influence of heart rate (HR) on measurements is largely unknown.Objectives: To investigate the use of 2-dimensional echocardiography (2DE), anatomical M-mode (AMM), tissue Doppler imaging (TDI), and 2D speckle tracking (2DST) at rest and after exercise for quantification of regional and global left-ventricular (LV) function.Animals: Five athletic Warmblood horses; 11.6 AE 3.6 years; 529 AE 48 kg. Methods: Prospective study. Three separate echocardiographic examinations were performed before (baseline) and over 5 minutes after treadmill exercise with 2DE (1st, short-axis view; 2nd, long-axis view) and pulsed-wave TDI (3rd examination). Offline analyses were performed at baseline and after exercise at HR 120, 110, 100, 90, and 80 minute À1 . Global and segmental measurements were compared by analysis of variance.Results: Quantitative analyses of stress echocardiograms were feasible in all horses. None of the AMM indices changed significantly after exercise. Stroke volume and ejection fraction by 2DE and strain by 2DST decreased, whereas strain rate by 2DST increased significantly at HR 4 100 minute À1 . TDI analyses were technically difficult and provided little additional information.Conclusions and Clinical Importance: Volumetric indices by 2DE and strain and strain rate by 2DST are applicable for quantitative assessment of stress echocardiograms. In healthy horses, they are significantly altered at a HR 4 100 minute À1 and need to be evaluated in view of the instantaneous HR. Further investigations are needed to define the clinical value of stress echocardiography in horses with cardiac disease.

Echocardiographic Assessment of Left Ventricular Function in Healthy Horses and in Horses with Heart Disease Using Pulsed‐Wave Tissue Doppler Imaging

“…The missing data are related to the short timing and relatively low velocity of isovolumic events and the influence of image quality, motion artifacts, and other individual patient factors, leading to a low signal‐to‐noise ratio. In previous studies evaluating the use of PW TDI and color‐coded TDI measurements in horses, variables characterizing the isovolumic periods showed low‐to‐moderate variability and, in agreement with this study, they could not be measured in all horses and in all recorded cycles 14, 18. These findings highlight the importance of optimizing image quality and of capturing multiple sequential recordings containing several cardiac cycles to maximize the chances of obtaining diagnostic information.…”

“…This was not demonstrated in horses with MR and AR, respectively. The decrease in E m cannot be explained by higher heart rate, as E m has previously been shown to increase with tachycardia 18. As stated above, none of the horses with myocardial disease were clinically volume‐depleted at the time of echocardiography, suggesting that the results can also not be explained by a decrease in venous return and preload.…”

“…In adult horses, true apical views cannot be obtained and adequate alignment of the Doppler beam with longitudinal mitral annular motion cannot be achieved. Therefore, TDI recordings for the assessment of LV function are usually limited to radial wall motion of the LV free wall at the chordal level that can be reliably assessed by standard short‐axis views, allowing optimal alignment with wall motion 14, 15, 16, 18. In dogs and cats, both longitudinal motion and radial motion have been studied and both were considered diagnostically valuable 9, 39.…”

“…All echocardiographic recordings had been obtained by a single observer (CCS) according to previously described imaging standards14, 18, 19 and had been stored as still images or cine loops in digital raw data format 3…”

Strain and strain rate by two-dimensional speckle tracking echocardiography in a maned wolf

“…In veterinary medicine there have been studies that reported the use of 2D-STE in domestic animals (Chetboul et al 2007, Schefer et al 2010, Decloedt et al 2011, Grifϐiths et al 2011, Takano et al 2011, Wess et al 2011. In dogs it was demonstrated that 2D-STE is a feasible and useful tool to assess myocardial function (Chetboul et al 2007, Wess et al 2011, as it is able to detect early alterations (Takano et al 2011).…”