Lecture 14 - Cardio 5

Question 1

What is a cardiomyopathy?

Answer 1

Well defined clinico-pathologic entities that are either genetic abnormalities of myocardial contracture or are responsive to substances such as taurine

Question 2

What are some features of cardiomyopathy?

Answer 2

Features include cardiomegaly (dilation or hypertrophy), mural thrombosis (left ventricle) and fibrosis

Question 3

How is a diagnosis of cardiomyopathy made?

Answer 3

Diagnosis is based on absence of significant congenital or acquired valvular or vascular abnormality. Presence of dilation or hypertrophy of one or both ventricles (possibly all four) and accompanied in some cases by diffuse fibrosis

Question 4

What is the name of the condition that is shown below?

Answer 4

Hypertrophic cardiomyopathy (HCM)

Question 5

Breifly describe the condition that is shown below and state what other clinical findings may be found post-mortem:

Answer 5

Dilated cardiomyopathy - decreased markedly in prevalence since discovery of taurine-deficiency myocardial failure in cats. Omn post mortem all chambers of the heart are enlarged and the ventricles are dilated and flabby with thinned walls

Question 6

What is the name of the condition that is shown below and what was a likely preceding factor?

Answer 6

Restrictive cardiomyopathy is a result of impaired diastolic ventricular filling due to severe endomyocardial fibrosis. Endomyocarditis was likely a preceding factor in this case

Question 7

Hypertrophic cardiomyoparthy is very rare in dogs. How does hypertrophic cardiomyopathy normally present?

Answer 7

In young dogs it normally presents as sudden and unexpected anaesthetic deaths or sudden death in otherwise healthy young dogs

Question 8

What is the most likely cause of cardiomyopathy in dogs and what is the prognosis of it?

Answer 8

Most causes of dilated cardiomyopathy in dogs have a genetic basis. The long term prognosis of this condition is very poor as it is a progressive condition

Question 9

What is the name of the condition that is shown in the condition below?

Answer 9

Dilated cardiomyopathy - dogs

Question 10

What is the name of the conditon shown below? Comment on the prevalence of it:

Answer 10

Cardiac neoplasia - primary cardiac neoplasia in all domestic species is quite rare. The exception = haemangiosarcoma in RA of dogs

Question 11

What are three examples of congenital cardiac diseases that would result in systemic to pulmonary (left to right) shunting?

Answer 11

1. Patent ductus arteriosus
2. Atrial septal defects
3. Ventricular septal defects

Question 14

What are some congenital cardiac diseases that can result in malformation of semilunar or atrioventricular valves?

Answer 14

1. Pulmonary stenosis
2. Sub-aortic stenosis

Question 15

What is a patent ductus arteriosis?

Answer 15

Develops from the sixth left brachial arch of the fetus and diverts a major portion of blood from the aorta to the pulmonary artery

Question 16

What is an atrial septal defect?

Answer 16

It is failure of the closure of the foramen ovale - an interatrial shunt allowing blood to bypass the lungs of the fetus

Question 17

Describe the sequelae of events that arises from an atrial septal defect:

Answer 17

1. Excessive flow from the left to the right atrium - resultant voluem overload on right ventricle and subsequent elevated central venous pressure
2. Results in right ventricular hypertrophy
3. Developement of pulmonary hypertension

Question 18

What is a ventricular septal defect and what are the consequences of it ?

Answer 18

A ventricular septal defect failure is lack of complete developement of intraventricular septum allowing the shunting of blood between them. This results in the left ventricle being enlarged and accompanied by mild sub-endocardial fibrosis following chronic dilation.

Question 19

Briefly describe the sequelae of events invovled in ventricular septal defects:

Answer 19

1. VSD has no deleterious effects on the fetus because left and right ventricular pressures are equal
2. The left ventricular ouptut is maintained by an increase in end-diastolic volume and augmenation of contractility by Frank-Starling mechanism (right ventricular pressure then = left ventricular pressure so the right ventricle now has a greater systolic and diastolic load –> pulmonary hypertension. Both ventricles then undergo hypertrophy the left being more obviously eccentric in nature)
3. The pulmonary hypertension has the potential to lead to shunt reversal (right –> left, that results in cyanosis and death)

Question 20

What changes occur in an animal with pulmonic stenosis?

Answer 20

post-stenotic dilation of the pulmonary artery

Question 21

What is the gross appearance of aortic and sub-aortic stenosis?

Answer 21

The gross appearance of sub-valvular lesions is a small number of fibrous plaques on the endocardial surface of the left ventricular outflow tract. The aortic valves are also frequently involved are are thickened

Question 22

What are the sequelae to aortic and sub-aortic stenosis?

Answer 22

Increased afterload on the LV and turbulent post stenotic flow –> compensatory concentric hypertrophy of the ventricle and post stenotic dilation of the aorta. Intimal proliferation of collagen and deposition of glycosamines in intramural arteries is common with increased risk of mutlifocal myocardial necrosis and fibrosis

Question 23

What is arteriosclerosis?

Answer 23

Arteriosclerosis is hardening of the arteries. Chronic arterial change consists of hardening, loss of elasticity and luminal narrowing

Question 24

What are some causes of arterial mineralisation?

Answer 24

The causes of arterial medial calcification include:

• Vitamin D toxicosis - calcinogenic plant toxicosis
• Renal insufficiency
• Severe debilitation - as seen in cattle with Johne’s disease

Question 25

What is an aneurysm?

Answer 25

An aneurysm = localised dilation of any vessel (infrequent in domestic animals other than turkeys)

Question 26

What is a dissecting aneurysm?

Answer 26

When blood enters the wall of an artery through an intimal tear - it dissects between medial layers and creates a cavity within the arterial wall.

Question 27

What are some examples of emboli other than thromboemboli?

Answer 27

Air embolism = right ventricle may cause fatal blockage of circulation

Foreign bodies = pellets or bullets may be embolic and occlude larger vessels

Larval and adult parasites = may cause emboli in the system

Fibrocartilagenous embolism = resutls in necrotising myelopathy in dogs, pigs and humans

Question 28

What is lymphangiectasis?

Answer 28

Results from obstruction and leads to the accumulation of excess interstitual fluid in the drainage area.

Question 29

What are the important sampling blocks for histopathology?

Answer 29

Block 1 - AV node

Block 2 - tissue slice no thicker than 1 cm including the interventricular septum and paillary muscle of the left ventricle

Block 3 - right ventricular wall including endocardium, myocardium and pericardium