Due to its acute clinical presentation and economic relevance, colic plays an important role in equine medicine. In order to improve treatment and clinical outcome, it is essential to evaluate cardiovascular function quickly in an emergency situation. In this study, the noninvasive assessment of myocardial impairment during acute colic by tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2D-ST) was evaluated. 36 horses presented with colic to the Equine Clinic of the FU Berlin were included. All patients were examined during acute colic on admission (day 1, U1) and right before discharge (day 3 for medically managed colic or day 7 for surgically managed colic, U2). The horses were separated into 3 groups by using a scoring system for severity of disease. Besides a complete clinical examination, blood tests (complete blood count, venous blood gas analysis), including cardiac troponin I, and echocardiography in right parasternal short axis view were performed. 2DE, M- mode, pulsed waved TDI, color TDI and 2D-ST were used. For all measurements, three cardiac cycles were recorded. Further analysis was performed offline with the Echopac software. For 3 regions (interventricular septum = IVS, right ventricular wall = RV, left ventricular wall = LV) maximum myocardial velocities S, E and A were determined, as well as time intervals ET, Ed, IVCT. By use of the 2D-ST software, the myocardium was divided into 6 segments, for each radial and circumferential strain (Sr, Sc) and strain rate during systole, early diastole and late diastole (SrS, SrE, SrA, ScS, ScE, ScA) were determined. In general, all measurements were feasible, even in an emergency situation. Blood tests showed significantly higher levels for hematocrit and lactate in group 3 (severe colic) compared to group 1 (mild colic). By using cTnI, myocarditis could be ruled out; however, no significant differences were found between groups. The myocardial velocities (Sm, Em, Am), obtained by PW-TDI, showed significant reductions between groups, especially in LV, but also Am in RV and IVS. In particular, maximum myocardial velocities Sm (systole), Em (early diastole) and Am (late diastole) in the LVS but also Am in the RVW and the IVS were significantly decreased in horses with severe colic (group 3) compared to horses with mild colic (group 1). In comparison, the measurements determined by colorTDI showed a trend for reduction in higher severity of colic during U1, but not significantly. The low levels in correlation with the severity of colic and the cardiovascular situation in part confirm the results of previous studies. Strain and strain rate through speckle tracking showed significant reduction of Sr in two myocardial segments (ant, antsept) between group 1 and group 3, depending on severity of the disease. Many individual levels were higher in group 1 than in group 2 or group 3 during U1; however these differences were not significant. When comparing the different days of examination, circumferential strain in the lateral segment (Sc lat) in group 2 was reduced significantly during discharge in comparison with acute colic. The results of the present study indicate that TDI and strain imaging obtained by 2D-ST is feasible even in an emergency situation. The results provide information about quantitative global and regional systolic and diastolic myocardial function, which facilitates adjustment of therapy and prognosis. Further studies with higher number of participants are essential to establish the techniques for clinical use in colic.
