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Echocardiography
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ECHOCARDIOGRAPHY
P a u l McClellan, D V M
In recent years there has been a surge of interest in the athletic physiology of the horse. The hope is that the knowledge gained will improve athletic performance; reduce injury rate and severity, and identify potential champions earlier and more accurately. One area where great advaoces are being made is in our knowledge of cardivascular conditioning in the horse. New methods such as performance profiling, telemetry EKGs and echocardiography are allowing us to learn more about the unique physiologic aspects of the equine heart. We can also investigate, in detail, the subtle abnormalities, imperfections, and diseases that cause the heart to fuoction at less than an optimal rate thus making it the limiting factor in performance. Electrocardiography is used in assessing the heart rate and electrical conduction properties of the heart. Echocardiography is a new technique using diagnostic ultrasound to observe heart structure in vivo. With this technique we can visualize the size, movement and relationship of all the valves and chambers of the heart. This technique is useful in such diseases as congenital heart defects, scarred valves secondary to endocarditis and pericarditis. Some conduction abnormalities can also be seen with ultrasound but these findings should be supported with the EKG. Some conduction problems, such as atrial fibrillation or conduction blockade, can become signifcant during exercise. What is the prevalence of cardiac disease in the racehorse? At the present time the rate of incidence of heart disease is unknown. One recent report estimated that 30% of horses racing may have some compromise of cardiac function. The point is, that cardiac disease is more prevalent than once thought and it does affect Volume 5, Number S
n
\~Long s '~/ scanplaxiane AO = Aorta L V = L e f t Ventricle R V = Right Ventricle. L A - L e f t Atrium RA
Right A t r i u m
Figure 1. This long axis view of the equine heart entails the normal architecture of the tricuspid valve. This is the common area affected by an infectious endocarditis. When viewing the right side of the heart, normal valve movement and normal texture and contraction of the cardiac muscle can all be evaluated.
345
Figure 2. These scans of the right heart are from a horse that had been racing poorly due to an active case of vegetative endocarditis. A supravalvular lesion of the tricuspid valve was
seen along with an extreme example of what has been described as particulate showering.
performance. When such clinical signs as chronic low grade fever, weight loss, and exercise intolerance, go unexplained then a cardiac exam may be indicated. As more hearts are scanned, the effects of cardiac disease on
the racehorse will be more completely understood. This will enable more specific drugs or surgical therapies to be devised. Just recently a pacemaker was successfully implanted in a horse's heart for the first time.
Send your address change six weeks prior to moving. 346
EQUINE VETERINARY SCIENCE
ECHOCARDIOGRAPHY
P a u l McClellan, D V M
In recent years there has been a surge of interest in the athletic physiology of the horse. The hope is that the knowledge gained will improve athletic performance; reduce injury rate and severity, and identify potential champions earlier and more accurately. One area where great advaoces are being made is in our knowledge of cardivascular conditioning in the horse. New methods such as performance profiling, telemetry EKGs and echocardiography are allowing us to learn more about the unique physiologic aspects of the equine heart. We can also investigate, in detail, the subtle abnormalities, imperfections, and diseases that cause the heart to fuoction at less than an optimal rate thus making it the limiting factor in performance. Electrocardiography is used in assessing the heart rate and electrical conduction properties of the heart. Echocardiography is a new technique using diagnostic ultrasound to observe heart structure in vivo. With this technique we can visualize the size, movement and relationship of all the valves and chambers of the heart. This technique is useful in such diseases as congenital heart defects, scarred valves secondary to endocarditis and pericarditis. Some conduction abnormalities can also be seen with ultrasound but these findings should be supported with the EKG. Some conduction problems, such as atrial fibrillation or conduction blockade, can become signifcant during exercise. What is the prevalence of cardiac disease in the racehorse? At the present time the rate of incidence of heart disease is unknown. One recent report estimated that 30% of horses racing may have some compromise of cardiac function. The point is, that cardiac disease is more prevalent than once thought and it does affect Volume 5, Number S
n
\~Long s '~/ scanplaxiane AO = Aorta L V = L e f t Ventricle R V = Right Ventricle. L A - L e f t Atrium RA
Right A t r i u m
Figure 1. This long axis view of the equine heart entails the normal architecture of the tricuspid valve. This is the common area affected by an infectious endocarditis. When viewing the right side of the heart, normal valve movement and normal texture and contraction of the cardiac muscle can all be evaluated.
345
Figure 2. These scans of the right heart are from a horse that had been racing poorly due to an active case of vegetative endocarditis. A supravalvular lesion of the tricuspid valve was
seen along with an extreme example of what has been described as particulate showering.
performance. When such clinical signs as chronic low grade fever, weight loss, and exercise intolerance, go unexplained then a cardiac exam may be indicated. As more hearts are scanned, the effects of cardiac disease on
the racehorse will be more completely understood. This will enable more specific drugs or surgical therapies to be devised. Just recently a pacemaker was successfully implanted in a horse's heart for the first time.
Send your address change six weeks prior to moving. 346
EQUINE VETERINARY SCIENCE