Congenital heart defects

Question 1

What are the main defects dogs get?

Answer 1

Common- Subaortic stenosis, PDA, Pulmonic stenosis
Uncommon - VSD, mitral or tricuspid dysplasia
Rare - Atrial spetal defect, ToF

Question 2

How can you manage subaortic stenosis?

Answer 2

Beta-blockers (eg, atenolol at 1 to 2 mg/kg twice daily or propranolol at 1 to 2 mg/kg three times daily) to decrease the likelihood of sudden death, but no trials exist to prove the efficacy of this therapy. Avoid these drugs, or use very cautiously, in animals with congestive heart failure
No Sx has been found effective yet

Question 3

What is subaortic stenosis most commonly seen in?

Answer 3

boxers and golden retrievers, but also in bulldogs, bull terriers, Newfoundlands and rottweilers

Question 4

What type of murmur is commonly noted with subaortic stenosis?

Answer 4

loudest over the left base although, very occasionally, it may be loudest on the right side. Mild cases have a brief murmur (grade 1 to 3) while severely affected dogs show a prolonged (pansystolic) murmur (grade 4 or more).

Question 5

What breeds is a PDA common in, and what does the murmur sound like?

Answer 5

Border collies, Cavalier King Charles and cocker spaniels, and German shepherd dogs. It is generally very easily detected as it causes a continuous murmur that is usually loud (grade 4 or more) over the left base of the heart

Question 6

What is the prognosis for PDAs?

Answer 6

PDA often leads to rapidly progressive left-sided cardiomegaly and left heart failure. If untreat-ed, about 65 per cent of affected animals will die within one year following the onset of congestive heart failure

Question 7

What are the treatment options for PDA?

Answer 7

normally surgical correction
In small dogs - direct surgical ligation
In bigger dogs - Amplatz device or similar

Question 8

How do you monitor the time for surgery in PDA puppies?

Answer 8

Frequent (three- or four-weekly) monitoring of left heart size using either radiology or echocardiography is essential in young puppies diagnosed with PDA. Repair may need to be undertaken at a very young age (possibly eight to 10 weeks) in severe cases, if clinical signs develop or if radiographic/echocardio-graphic changes are severe or rapidly progressive.

Question 9

What are the classic radiographic changes associated with a PDA?

Answer 9

‘bulges’ corresponding to the aorta, pulmonary artery and enlarged left atrium - not always seen though!

Question 10

Which breeds are predisposed to pulmonic stenosis?

Answer 10

boxers, Cavalier King Charles and cocker spaniels, labradors, and West Highland white and Yorkshire terrier

Question 11

What kind of murmur is heard in pulmonic stenosis?

Answer 11

systolic murmur over the left base of the heart, similar to that of aortic stenosis, is apparent on auscultation. Stenosis usu-ally occurs at the level of the pulmonary valves and can lead to progressive right ventricular hypertrophy on rads

Question 12

What are the indications for balloon valvuloplasty of pulmonic stenosis?

Answer 12

Marked symptomatic or asymptomatic right ventricular hypertrophy

Symptomatic pulmonic stenosis with mild to moderate degrees of right ventricular hypertrophy

Concurrent presence of significant tricuspid dysplasia where moderate to marked right atrial dilation is present. Such cases are likely to develop right heart failure. Intervention is likely to be beneficial, but should be performed before signs of right heart failure manifest. Once heart failure has ensued, the prognosis seems poor even after intervention

Question 13

What are potential clinical signs of pulmonic stenosis?

Answer 13

Sudden death without prior symptoms can occasionally occur in these dogs. More commonly, there will be signs of syncope or progressive exercise intolerance. Some severe cases can present with signs of ascites and distended jugular veins due to the onset of right heart failure. This is particularly prevalent in dogs with concurrent tricuspid valve incompetence.

Question 14

What are the common breeds found to have VSDs?

Answer 14

Border collies, springer spaniels and West Highland white terriers

Question 15

What is the standard murmur with a VSD?

Answer 15

a harsh murmur is noted low down on the right thorax. This is due to blood escaping across the defect from the high pressure left ventricle and striking the right ventricular wall. The defect may be small, moderate or large. Small defects are likely to produce a louder murmur than larger defects (ie, the murmur intensity is inversely related to the size of the ventricular septal defect).

Question 16

What may you see on rads with VSD

Answer 16

left-sided cardiomegaly, pul-monary overcirculation and even pulmonary oedema

Question 17

What, in order of occurence, occurs in cats?

Answer 17

Ventricular septal defect
Mitral or tricuspid valve dysplasia
Atrial septal defect
Endocardial cushion defect (atrioventricular septal defect)
Aortic  stenosis
Pulmonic  stenosis
Tetralogy of Fallot
 Patent ductus arteriosus

Question 18

Outline tricuspid dysplasia

Answer 18

most often diagnosed in labradors and is more commonly overlooked than other congenital defects, as the systolic right-sided murmur is usually not intense. Progressive right atrial enlargement and right heart failure can occur in severe cases. However, survival times are frequently much longer than those for severe mitral dysplasia

Question 19

outline ToF

Answer 19

Although rare, tetralogy of Fallot is a severe abnormality that leads to exercise intolerance and cyanosis, often in the first year of life. Keeshonds are predisposed to this condi-tion. Cyanosis may be present only on exertion in some dogs. Progressive polycythaemia will develop over time and, hence, regular haematocrit assessment is advisable

Question 20

Outline management of atrial septal defects

Answer 20

rarely necessary
Standard therapy for heart failure should be administered in cases of right heart failure
Surgical repair is not currently available

Question 21

Outline management of tetralogy of fallot

Answer 21

Beta-blockers (eg, atenolol at 1 to 2 mg/kg twice daily or propranolol at 1 to 2 mg/kg three times daily) appear to improve pulmonary flow during exercise and, therefore, may ameliorate hypoxaemia
Periodic phlebotomy should be carried out to maintain a haematocrit of less than 65 per cent
Hydroxycarbamide (medical phlebotomy) should be administered as described for ventricular septal defects, again to maintain the haematocrit below 65 per cent. This drug is unlicensed for veterinary use
Effective surgical treatment is not currently available. However, some experienced surgeons do undertake palliative surgery to improve systemic oxygenation with pulmonary circulatory anastomoses (eg, Blalock-Taussig shunt)Management of congenital defects in cats
Cats with PDA, which show substantial or pro-gressive left-sided cardiomegaly or heart failure, can be managed using:– Thoracotomy and duct ligation– Catheter-based closure with coils via a femoral vessel approach, as for dogs Cats with severe pulmonic stenosis, which are symptomatic, can be treated using balloon dilation via a jugular approach Standard therapy for heart failure can be insti-tuted for other conditions that lead to left or right heart failure Beta-blockers (eg, atenolol at 1 to 2 mg/kg twice daily or propranolol at 1 to 2 mg/kg three times daily) should be administered to cats with severe aortic stenosis (or severe pulmonic stenosis where balloon dilation is not chosen). Avoid these drugs, or use cautiously, if the cat is suffering from con-gestive heart failureCongenital defects in cats Ventricular septal defect Mitral or tricuspid valve dysplasia Atrial septal defect Endocardial cushion defect (atrioventricular septal defect) Aortic stenosis Pulmonic stenosis Tetralogy of Fallot Patent ductus arteriosusThe defects are

Question 22

How can you treat cats with congenital issues

Answer 22

Cats with PDA, which show substantial or pro-gressive left-sided cardiomegaly or heart failure, can be managed using:– Thoracotomy and duct ligation– Catheter-based closure with coils via a femoral vessel approach, as for dogs
Cats with severe pulmonic stenosis, which are symptomatic, can be treated using balloon dilation via a jugular approach
Standard therapy for heart failure can be insti-tuted for other conditions that lead to left or right heart failure
Beta-blockers (eg, atenolol at 1 to 2 mg/kg twice daily or propranolol at 1 to 2 mg/kg three times daily) should be administered to cats with severe aortic stenosis (or severe pulmonic stenosis where balloon dilation is not chosen). Avoid these drugs, or use cautiously, if the cat is suffering from congestive heart failure