Echocardiographic analysis of segmental left ventricular wall motion at rest and after exercise in horses with and without heart disease

An echocardiography was performed on 23 healthy warmblood horses and on 12 warmblood horses with cardiac diseases at rest and after treadmill or lungeing exercise. The B-mode technique was used, and the left ventricular wall motion was analyzed visually. The left ventricle was divided into 6 equally sized myocardial segments, 3 of them in the region of the interventricular septum, and the other 3 in the region of the left ventricular rear wall (“6-segment model”). The kinetic of each segment was determined using a kinetic score system. A normokinetic wall motion was defined with a kinetic index of 1. To the authorsʹ knowledge, the current study is the first to present a visual qualitative method for assessment of the healthy equine heart with regard to the myocardial left ventricular wall motion at rest and after exercise under standardized conditions. First, reference values for the left ventricular myocardial kinetics were established in healthy horses. Subsequently, horses with cardiac diseases of differing severity were examined, and the diagnostic value of the method was evaluated. In contrast with human cardiology, the healthy equine heart is characterized by several deviating wall motion patterns. The majority of the healthy horses (52%) showed a normokinetic wall motion of all 6 segments at rest and a normokinetic concentrically increased hypertrophy after exercise. In 9 healthy horses, however, the middle septal segment (at the papillary muscle level) was characterized by a hypokinesia (kinetics index = 2) at rest. In 5 of these horses, the hypokinesia was not observed after exercise. The kinetic wall motion score was 1.1 ± 0.2 at rest in the healthy horses. In the horses with cardiac disorders, the score was 1.5 ± 0.4 at rest. In all healthy horses, the middle septal segment (at the papillary muscle level) was characterized by a hypokinesia (kinetics index = 2; n = 5) or akinesia (kinetics index = 3; n = 3) at rest.