Download Ventricular Septal Defect (VSD)

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Ventricular Septal Defect (VSD)
Submitted by Dan Van Arsdall on Thu, May 12 @ 1pm
Description:
Ventricular septal defects (VSD) are a congenital [1] anatomical defect of the heart in which
there is a communication between the left and right ventricles. This abnormal opening allows
blood to flow from one ventricle to the other, usually from the left to the right when the heart
contracts to move blood out to the body. VSDs can be found as a single defect or in
conjunction with other cardiac abnormalities. While little is known about the cause of VSDs,
they may be heritable in Limousine and Hereford cattle.
Etiology:
While the true incidence of VSD in large animals is not know, VSD is the most common form
of congenital cardiac defect found. It is suspected that VDS is a heritable trait in Limousine
and possibly Herford cattle thus cattle of these breeds with VSD should not be bred. Specific
causes of VSD are knot known.
Symptoms:
The symptoms seen depend on the size of the defect in the heart as well as the pressure
within the ventricles and pulmonary arteries. Cattle with smaller defects often do not show any
signs of illness. In the case of larger defects, cattle are prone to developing signs of rightsided heart failure. Signs of right-sided heart failure include ascities, fatigue, poor growth, and
exercise intolerance. In addition, animals with a VSD can develop congestive heart failure due
to a chronic overload in both ventricles. When blood rushes back and forth across a septal
defect it creates significant turbulence and this damages the inside of the heart, the
endocardium. Endocardial damage predisposes an animal to developing blood clots (thrombi)
and may cause structural damage to the aortic valve.
Diagnosis:
Diagnosing VSD usually begins with a physical examination. Typically, a VSD is accompanied
by a systolic heart murmur heard on both sides of the chest. The murmur is usually loudest on
the right, but this can vary. With a very large defect, a murmur is not always heard. A palpable
cardiac thrill is usually present. Other diagnostics available to help identify VSD include
radiographs and echocardiography. Thoracic radiographs may show an enlarge heart, but this
finding is not unique to VSD. Echocardiography is the diagnostic technique of choice because
it allows one to visualize the size and location of the defect as well as the direction of blood
flow through the communication between the ventricles. At necropsy, most VSDs can be
found just ventral to the aortic valve in the left ventricle and underneath the tricuspid valve
septal leaflet in the right ventricle. If the defect is large, generalized cardiomegaly might also
be present and the lungs may be congested. Finally, there may be lesions within the heart
associated with turbulent blood flow.
Prevention:
The best method of preventing VSD is to identify affected animals and remove them from the
breeding stock. Bulls with VSD are not typically accepted into breeding programs because
there is evidence that this is a heritable defect in cattle, particularly in the Limousine and
Herford.
Treatment:
There is no practical treatment for VSD in cattle. Animals diagnosed with moderate to large
VSD based on echocardiography have a poor prognosis for normal production. Animals with
only small defects may remain asymptomatic throughout life but should still be identified
because they may develop loud heart murmurs. It is inadvisable to breed any animal with a
ventricular septal defect because of the evidence that this defect is heritable in cattle.
Sources:
Smith, B.P. Large Animal Internal Medicine, 3rd Ed. Mosby-Elsevier Publishing. St. Louis,
MO. 2009. pp.448-451.
Merck Veterinary Manual Online:
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/11111.htm&word=... [2]
vsd.jpg [3]
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Links:
[1] http://calfology.com/glossary/6/letterc#term290
[2]
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/11111.htm&word=ventricular%2csepal%2cdefect
[3] http://calfology.com/sites/default/files/photo_gallery/vsd.jpg