Demonstration of regional differences in equine ventricular myocardial velocity in normal 2-year-old Thoroughbreds with Doppler tissue imaging.
BACKGROUND
Doppler tissue imaging (DTI) is a novel noninvasive method by which myocardial velocity can be assessed directly and it allows regional, rather than global, cardiac function to be evaluated.


OBJECTIVE
That regional differences in myocardial velocities exist within the equine ventricle.


OBJECTIVE
To develop a repeatable examination technique for DTI in horses, describe DTI findings in various regions of the normal equine ventricle, compare colour (CDTI) and spectral (SDTI) techniques of DTI, and document regional differences in myocardial velocity.


METHODS
Five regions of the ventricles (right ventricular wall, interventricular septum and left, right and caudal regions of the left ventricle) were evaluated using SDTI and CDTI in 20 clinically normal Thoroughbreds age 2 years. Individual repeatability of the method was determined by examination of one 6-year-old Thoroughbred on 6 occasions.


RESULTS
Three major movements were observed in the ventricular walls in systole, early diastole and late diastole. The interventricular septum had a complex pattern of movement. The left region of the left ventricle and interventricular septum had the most rapid movement. The individual repeatability of CDTI was poor, while in systole and early diastole, but not late diastole, SDTI produced repeatable estimates of maximal myocardial velocity. The different velocity estimates obtained with SDTI and CDTI are not interchangeable. Regional differences in the peak mean and maximal myocardial velocities were found in systole and early diastole (P<0.05), but were not identified in late diastole.


CONCLUSIONS
The SDTI modality appears to produce the most repeatable data. There are regional differences in myocardial velocity within the equine ventricles for systole and early diastole.


CONCLUSIONS
DTI shows potential as a tool for studying regional myocardial movement both in clinical cases suspected of having myocardial dysfunction and in a research setting. In particular, SDTI offers potential as a direct and noninvasive means to study early diastolic function of the equine ventricles.
Sepulveda
M F
MF
Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, North Mymms, Hertfordshire AL9 7TA, UK.
Perkins
J D
JD
Bowen
I M
IM
Marr
C M
CM
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology / Q000662:veterinary*; D018618:Echocardiography, Doppler, Color / Q000379:methods / Q000662:veterinary*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006736:Horses / Q000502:physiology*; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D015588:Observer Variation; D015203:Reproducibility of Results; D016276:Ventricular Function / Q000502:physiology