Prospective study of hemodynamic disorders mesured by echocardiography and associated with endotoxemia in horses

Endotoxemia is the first mortality cause in intensive care horses. In human, hemodynamic disturbances have been showed to be associated with septic shock whereas in horses, this facet of endotoxemia has not yet been studied. The aim of the study was to assess the impact of endotoxin shock on equine cardiac function. Fifty horses admitted in clinic with signs of endotoxic shock and 17 healthy control horses were submitted to a doppler echocardiographic exam. The endotoxemic horses were classified in 4 groups according to their shock score based on clinical evaluation (heart rate (HR) and respiratory rate), non invasive systolic blood pressure, and blood tests (Packed cell volume and lactates). Score 1, 2, 3 and 4 groups included 11, 17, 12 and 10 horses, respectively. Left ventricular (LV) echocardiographic and Doppler parameters were compared between the 5 groups using a multivariable ANOVA analysis. The LV internal diameter, ejection time, ejection time corrected for HR and mean velocity of circumferential fiber shortening corrected for HR, the aortic velocity time integral and deceleration time, and the stroke volume were significantly lower, whereas the HR and the peak velocity of the late diastolic filling of the mitral Doppler flow and its velocity time integral were significantly higher in grade 2 to 4 endotoxemic horses than in control horses. Because of the tachycardia compensating the lower stroke volume in endotoxemic horses, the cardiac output was not significantly different between groups. Despite the fact that the increase in HR, the fall in preload and a probable decrease in afterload doubtless played a role in the observed changes, the results of this study suggest an impaired systolic and diastolic LV function in horses with moderate to severe endotoxemia. Doppler echocardiographic monitoring of the cardiovascular function could thus be of interest in equine intensive care.