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

Abstract

BackgroundAssessment of left ventricular (LV) function by tissue Doppler imaging (TDI) is not well established in horses with heart disease.ObjectivesTo describe the use of pulsed‐wave (PW) TDI for the assessment of LV function, establish reference intervals, investigate effects of mitral regurgitation (MR), aortic regurgitation (AR), and primary myocardial disease (MD), and provide proof of concept for the use of PW TDI in Warmblood horses with heart disease.AnimalsThirty healthy horses, 38 horses with MR, 25 with AR, 8 with MD.MethodsEchocardiograms were retrospectively analyzed. Reference intervals were calculated. PW TDI indices of healthy horses and horses with MR, AR, and MD were compared by one‐way ANOVA and Dunnett's test.ResultsA complete set of PW TDI variables could be obtained in 94 of 101 horses. Variables corresponding to isovolumic intervals were most difficult to measure. Valvular regurgitation influenced variables describing isovolumic contraction and ejection. Horses with MD had significantly shortened ETm (−118.5 [−154.1 to −82.9] ms; mean difference [95% CI of difference of means]), increased PEPm/ETm (0.11 [0.05 to 0.17]), prolonged IMPm (0.28 [0.18 to 0.37]), increased S 1 (8.9 [5.2 to 12.6] cm/s), and decreased E 1 (−2.6 [−4.7 to −0.5] cm/s), E m (−14.2 [−19.9 to −8.5] cm/s), and E m/A m ratio (−1.6 [−2.6 to −0.6]).Conclusions and Clinical ImportancePulsed‐wave TDI might be useful for detection of LV dysfunction in horses with primary MD. The clinical value of TDI in horses with MR and AR remains uncertain.

Assessment of systolic and diastolic function in clinically healthy horses using ambulatory acoustic cardiography

“…Conversely, LVST, lasting from the start of isovolumic contraction (S1) to the end of ejection (which is timely related to the second heart sound, S2) should be longer than LVET, which lasts from begin to end of ventricular ejection (aortic valve opening to closure) . This is concurrent with recent studies using tissue Doppler imaging for assessment of left ventricular function in horses, in which reported PEP (127 ± 25.3 ms; 121 ± 14.1 ms) was longer than EMAT and LVET (404 ± 18.9 ms; 421 ± 24.7 ms) was shorter than LVST reported in this study, respectively . Both EMAT and LVST are shorter in people compared to horses , which can be explained by different body mass and cardiac size.…”

“…In a recent study, it was shown that systolic time intervals can be altered in horses with mitral and aortic insufficiency, but their clinical value could not be well documented and remains uncertain at this time . Similarly, S3 can be heard in healthy horses and in horses with heart disease, but lacking accurate methods for quantification of the strength of S3, its diagnostic and prognostic value in horses with heart disease is not well established .…”

Detection of subclinical left ventricular dysfunction by tissue Doppler imaging in horses with aortic regurgitation

“…Koenig et al . investigated the use of pulsed wave TDI to measure LV function in healthy horses and horses with different cardiac diseases . In that study, results from horses with AR were inconclusive.…”

Diagnostic value of noninvasive pulse pressure measurements in Warmblood horses with aortic regurgitation

“…The finding of increased MWT d and RWT d in horses with mild AR indicates that some concentric remodeling occurs in this population of horses, whereas the decreased RWT d seen in the horses with severe AR indicates that the chamber enlargement is becoming disproportionate to wall thickness. The fact that indices of LV systolic function are not different among the AR severity subgroups highlights the difficulty in using these variables to judge the severity of AR, as has been described in 2 recent studies evaluating other methodologies to identify subtle changes in myocardial function …”

“…Because indices of LV size were included in the AR severity scoring system used to classify AR severity, it is logical that these indices would be different among the AR severity subgroups. The extent of LV enlargement in the AR severity subgroups was similar to that recently reported in other studies assessing the severity of AR using echocardiographic measurements . However, it is also clear that horses with severe AR show signs of LA enlargement indicating the hemodynamic relevance of severe AR resulting in increased preload of both the LV and LA.…”