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ATRIAL SEPTAL DEFECTS
Note for Pet Owners:
This information is provided by
Provet for educational purposes only.
You should seek the advice of
your veterinarian if your pet is ill as only he or she can correctly advise
on the diagnosis and recommend the treatment that is most appropriate for
your pet.
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Description
The two atrial chambers of the heart are separated by a musculo-fibrous wall called a septum. When part or all of this septum tissue is missing it is called a defect.
This type of defect needs to be differentiated from other abnormal connections across the septum, such as patent foramen ovale, which results from the failure of a normal foetal opening to close.
Atrial septal defects can occur in conjunction with other abnormalities such as valve defects.
Cause
The cause is thought to be a genetically inherited defect.
Breed Occurrence
Atrial septal defects are uncommon in dogs, but a genetic predisposition is
suspected when it does occur particularly in Boxers, Old English Sheepdogs and
Samoyeds.
Signs
If the defect is small the animal may show no signs at all. There is usually no murmur with small defects because the blood flow velocity through the defect is low. Such cases usually live a normal lifespan.
Animals with large defects develop signs of heart failure before they are 1 year old and, if the defect is severe, rarely survive beyond 4 years of age. Signs include :
Feinting/collapse (syncope)
with abnormal lung sounds if pulmonary congestion is presentAbnormal heart sounds (murmur) may be heard when the heart is examined with a stethoscope (called auscultation)
Complications
Diagnosis
Auscultation - may be no murmur, but with large defects there may be a murmur similar to that heard in pulmonic stenosis. Lung sounds may be heard - crackles, rales or wheezes.
X-rays - Often normal. Occasionally right side enlargement of the heart
ECG - Usually no abnormalities.
Echocardiography shunt flow through the defect can be visualised on Doppler echocardiography. Sometimes intravenous contrast needs to be administered to identify the defect clearly.
Cardiac catheterisation with a contrast study is the most reliable method of diagnosis.
Treatment
Most animals with atrial septal defects are not diagnosed, and even when they
are they do not need treatment. Depending upon the size and location of the
defect, surgical repair may be possible in animals with severe defects. Open
heart surgery is becoming increasingly common in dogs. Intermediate cases may be
treated medically for congestive heart failure by controlling salt intake and
the use of diuretics.
Prognosis
Good for most cases. Poor for very severe cases unless repaired surgically.
Long term problems
Updated January 2016
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