2.2: Cardiac pathology

Question 1

What are some possible malformations that could cause systemic to pulmonary (left to right) shunting?

Answer 1

• Ventricular septal defect (VSD)
• Patent ductus arteriosus (PDA)

Question 2

What are some possible malformations of the semilunar or atrioventricular valves?

Answer 2

• Pulmonic stenosis
• Tetrallogy of Fallot
• Dysplasia of the right atrioventricular valve

Question 3

What is the most common cardiovascular lesion in dogs?

Answer 3

Myoxmatous valvular degeneration

a.k.a. Degenerative valvular disease, sometimes “endocardosis”

Question 4

Hypertrophic cardiomyopathy presents as a systolic or diastolic disorder?

Answer 4

Diastolic

The heart is struggling to fill because the lumen is drastically narrow

Question 5

True/false: HCM in cats can be inherited.

Answer 5

True

Inherited as an autosomal dominant trait in Maine Coon and Ragdoll cats

Question 6

Describe why a VSD does not present an issue for the foetus, but causes a shunt after birth.

Answer 6

• In the foetus, left and right ventricular pressures are equal, so there is no deleterious effect.
• After birth, pulmonary vascular resistance usually drops. This means that with a VSD, there is a left to right shunt.

Question 7

A patent ductus arteriosus means there is a communication between which two structures in the heart?

Answer 7

PDA = communication between pulmonary artery and aorta

Question 8

What effect does a PDA have on the heart?

Answer 8

• There is increased afterload and consequent concentric hypertrophy of the right ventricle.
• The increase in blood volume returning from the pulmonary circuit means there is **eccentric hypertrophy of the left atrium and ventricle. **