ECHOCARDIOGRAPHY IN HORSES WITH AND WITHOUT HEART MURMURS IN AORTIC REGURGITATION

The hearts of 250 horses were examined clinically and echocardiographi cally with conventional M-mode and B-mode techniques as well as with p ulsed and in parts with colour Doppler techniques. Of these horses 45 showed aortic regurgitation that was detected by dopplerechocardiograp hy. In 29 of these horses a discernible diastolic murmur was localized over the aortic valve. In the remaining 16 horses no murmur over this valve could be found by auscultation. Of the horses with a murmur 12 showed a widening of the echo of che semilunar cusp. In 11 horses an o stium of regurgitation was detected. The inner diameter of the left ve ntricle and the aortic root was significantly larger in horses display ing a murmur compared to chose without. Differences in presystolic clo sure of the mitral valve, diastolic flutter of the anterior cusp of th e mitral valve, and the shortening fraction (FS%) between horses with and without cardiac murmur were statistically obvious but not signific ant. Horses with cardiac murmur showed a significantly higher intensit y of the Doppler signal compared to horses without murmur. The average maximal flow of the regurgitationjet in horses with diastolic cardiac murmur (V-max = 2,1 +/- 0,3 m/sec) were statistically significant hig her than in horses without diastolic heart murmur (V-max = 1,1 +/- 0.3 m/s). Coloured Dopplerechocardiography in horses with murmur showed r egurgitationjets of clearly larger extent compared to horses without d iastoiic murmur. Statistically the loudness of a cardiac murmur could nor be related to the degree of disease or to flow speed and now inten sities found Dopplerechocardiographically. In the future a distinction should be made between physiological and pathological aortic insuffic iency in horses as well as in other species. In addition to clinical d iagnostics conventional as well as pulsed and colour coded Dopplerecho cardiography is suggested for the evaluation of the hemodynamic releva ncy of aortic regurgitation.