Congenital Cardiac Disease

Question 1

1. 3 most common canine cardiac congenital defects.
2. Most common feline cardiac congenital defects.
3. Other canine cardiac congenital defects.
4. Other feline congenital cardiac defects.

Answer 1

1. • Subaortic stenosis.
     - Pulmonic stenosis.
     - PDA.
2. • Ventricular septal defect.
     - Mitral or tricuspid valve dysplasia.
3. • Mitral or tricuspid valve dysplasia.
     - VSD.
     - Tetralogy of Fallot.
4. • PDA.
     - Tetralogy of Fallot.

Question 2

Presentation of a congenital cardiac defect.

Answer 2

• Incidental finding.
• Heart murmur detected at vac.
• Exercise intolerance, weakness.
• Syncopal episodes / sudden death.
• Cyanosis (R to L shunting).
• Heart failure.

Question 3

1. Where would a pulmonic/aortic stenosis be heard on auscultation?
2. Where would a mitral valve murmur be heard on auscultation?
3. Where would you hear a PDA (continuous) on auscultation?
4. Where is a VSD most likely to be heard on auscultation?
5. Where would you hear a tricuspid valve murmur on auscultation?

Answer 3

1. Left heart base.
2. Left heart apex.
3. Cranial and dorsal on the left.
4. Right heart base.
5. Right heart apex.

Question 4

1. Physiological murmur in puppy/kitten characteristics.
2. Relationship between audibility of murmur and the severity of it.
   – exception to this.

Answer 4

1. No murmur >6 months of age.
   No high grade murmur.
   No diastolic or continuous murmur.
2. Louder murmur = more severe.
   – VSD.

Question 5

1. Aortic stenosis breed predispositions.
2. Types of aortic stenosis.
3. Until what age does the stenosis grow?

Answer 5

1. Boxer, Newfoundland, Gold Retrievers, Rottweiler, GSD.
2. Sub-valvular, valvular, supravalvular.
3. ~18 months old.

Question 6

Presentation of aortic stenosis.

Answer 6

• L sided systolic murmur at the heart base.
• Asymptomatic, exercise intolerance.
• Syncope on excitement/exercise.
• Ventricular arrhythmia. sudden death.
• L sided CHF.

Question 7

Aortic stenosis pathophysiology.

Answer 7

Stenosis&raquo_space; increased left ventricular pressure&raquo_space; L ventricular concentric hypertrophy&raquo_space; post stenotic dilatation&raquo_space; eventual L sided heart failure.

Question 8

Why does syncope occur w/ aortic stenosis?

Answer 8

Fixed obstruction limits CO during exercise (vasodilation – further drop in BP).
Increased LV pressure:
- mechanoreceptor stimulation.
- inappropriate bradycardia and vasodilation.
Inadequate myocardial blood supply - arrhythmias.

Question 9

Dx tests for aortic stenosis.

Answer 9

• Echocardiography.
• ECG – arrhythmias.
• Thoracic radiographs – CHF.
• Lung ultrasound.

Question 10

Determining the severity of aortic stenosis.

Answer 10

• Echocardiography.
• Flow velocity measurement (normal <2m/s).
• Pressure gradient (4 x velocity^2):
  – mild <40mmHg.
  – moderate 40-80mmHg.
  – severe >80mmHg.

Question 11

Aortic stenosis treatment.

Answer 11

Beta blocker (atenolol).
- if clinical signs, ventricular hypertrophy, ventricular arrhythmia.
- reduces HR so increases efficiency.
- prolongs diastole for better myocardial perfusion.
- anti-arrhythmic drug.
If CHF develops:
- Furosemide.
- ACE-inhibitor.
- Spironolactone.
- Pimobendan contraindicated.
– fixed outflow tract obstruction.

Question 12

1. Pulmonic stenosis breed dispositions.
2. Types.

Answer 12

1. Small breed dogs – French bulldog, English bulldog, cocker, Labrador).
2. Sub-valvular, valvular, supravalvular (but mainly valvular).
   Type A = leaflets normal but are stuck together.
   Type B = leaflets thickened.
   Can also be down to pulmonary h=artery hypoplasia.

Question 13

1. Pulmonic stenosis progression?
2. Pulmonic stenosis pathophysiology.

Answer 13

1. No progressions.
2. Outflow tract obstruction&raquo_space; pressure overload&raquo_space; R ventricular hypertrophy (+/- dilatation)&raquo_space; post stenotic dilatation&raquo_space; R sided heart failure.

Question 14

1. Presentation of patient w/ pulmonic stenosis.
2. Dx tests for pulmonic stenosis.

Answer 14

1. L sided systolic heart base murmur.
   Asymptomatic, exercise intolerance.
   Syncope on excitement/exercise.
   R sided CHF.
   Tricuspid dysplasia/regurgitation.
2. Echocardiography.
   ECG – arrhythmia.
   Thoracic radiographs.

Question 15

Pulmonic stenosis Tx.

Answer 15

Beta blocker (atenolol).
- if clinical signs. ventricular hypertrophy.
Balloon valvuloplasty.
- valvular pulmonic stenosis (severe).
– stent if do not respond well to this.
If CHF develops:
- Furosemide.
- ACE inhibitors.
- Spironolactone.
- NO pimobendan.

Question 16

Px of pulmonic stenosis.

Answer 16

If successful balloon valvuloplasty.
- normal life expectancy.
Worse Px:
- severe stenosis.
- clinical signs.
- younger age.
- pulmonary artery hypoplasia.
- R-CHF.

Question 17

1. PDA breed disposition.
2. PDA presentation.

Answer 17

1. Chihuahua, collie, maltese, poodle, pomeranian, english springer spaniel, GSD, Newfoundland, Labrador.
2. Asymptomatic.
   L-CHF.
   Continuous heart murmur.
   Frequently palpable thrill (grade 5-6/6).

Question 18

1. Why is the ductus arteriosus present in the first place?
2. When would the ductus arteriosus normally close?
3. Normal process of DA closure.
4. But w/ PDA?

Answer 18

1. Part of foetal circulation.
   - Diverts RV output to systemic circulation so it bypassing the non-functional, deflated foetal lungs.
2. By 7-10d after birth.
3. Initial closure by vasoconstriction in respond to first breath. Then replaced by fibrous tissue. Becomes ligamentum arteriosum.
4. A lot of smooth muscle replaced with elastic fibres.

Question 19

PDA heart characteristics.

Answer 19

L sided dilatation.
Increased LV SV, rapid run off of blood into pulmonary.
Reduced myocardial contractility when ventricle v enlarged and myocardium failing.
L sided CHF.

Question 20

PDA Dx tests.

Answer 20

Echocardiography.
- volume overload left side, myocardial function.
- PDA size and shape – funnel v tube.
- flow through PDA.
Thoracic radiographs.
- over-circulation.
- 3 ‘knuckles’ – enlarged aortic arch, enlarged pulmonary artery, enlarged left auricle.

Question 21

PDA Tx.

Answer 21

Closure of PDA asap. Normal QQoL.
Interventional device closure.
- Amplatz Canine Duct Occluder.
- Coils.
Surgical closure.

Question 22

1. Typical location of VSD in dogs and cats.
2. Usual direction of flow through the VSD?
3. Murmur of VSD.

Answer 22

1. Just below aortic valve.
2. L to R - pressure gradient.
3. Loud right sided systolic sternal murmur of grade 5/6.
   Smaller VSDs louder, larger VSDs quieter.

Question 23

Tetralogy of Fallot.

Answer 23

Pulmonic stenosis, RV hypertrophy (secondary to PS, VSD, overriding aorta.
Aorta larger than pulmonic artery and takes blood from both left and right.
Pulmonic stenosis may cause higher pressure in the RV so may cause R to L shunt through the VSD – exacerbated w/ exercise –> cyanosis.