Cardiovascular Pathology II

Question 1

What is a cardiomyopathy?

Answer 1

Generalised term for diseases of the heart muscle where the walls of the heart chambers have become thickened or stiff

Question 2

What is primary mycardial disease?

Answer 2

• Typically idiopathic (infectious)
• The disease is intrinsic to the myocardial fibre

Question 3

What is secondary myocardial disease?

Answer 3

• Usually the result of a known external insult
• Potentially metabolic cause (toxic, infectious neoplastic)
• The disease is not intrinsic to the myocardial fibre

Question 4

What are the five types of primary cardiomyopathy types?

Answer 4

1. Dilated
2. Hypertrophic
3. Restrictive
4. Arrhythmogenic right ventricular
5. unclassified

Question 5

What predisposes a dilated primary cardiomyopathy?

Answer 5

• Large breed dosg e.g doberman pinschers, portugese water dogs, irish wolfhounds

Question 6

What effect does a dilated primary cardiomyopathy have on the cardiac cycle?

Answer 6

• Causes systolic dilation- lowered inotropy with increased ventricular ESV

Question 7

What is the gross pathology of a dilated primary cardiomyopathy?

Answer 7

• Dilation of atria and ventricles, increased annulus circumference
• Eccentric hypertrophy of ventricles

Question 8

What breeds are most predisposed to a hypertrophic primary cardiomyopathy?

Answer 8

• Most common in cats
• Maine Coos/ Ragdolls, any cat with cardiac myosin binding protein C
  *

Question 9

What effect does Hypertrophic primary cardiomyopathy have on the cardiac cycle?

Answer 9

• Diastolic dysfunction- impaired lusitropy (ventriclar compliance and filling)

Question 10

What is a saddle thrombus?

Answer 10

• Thromboembolus at the aortic trifurcation

Question 11

What is a saddle thrombus the sequelae for?

Answer 11

• hypertrophic cardiacmyopathy

Question 12

How does a thromboembolus in the aortic trifurcation occur?

Answer 12

Thrombus forms in the left atrium
thrombus dislodges and passes through the aorta
lodges in the aortic trifurcation
causes distal limb ischemia

Question 13

What predisposes a restrictive primary cardiomyopathy?

Answer 13

• It’s relatively infrequent
• potential sequelae of endomyocarditis

Question 14

What effect does a restrictive primary cardiomyopathy have on the cardiac cycle?

Answer 14

• Diastolic dysfunction
• restricted ventricular filling

due to increased stiffness of the ventricular myocardium

Question 15

What is the gross pathology of a restrictive primary cardiomyopathy?

Answer 15

• Endomyocardial fibrosis
• excessive moderator bands
• Atria typically dilate with normal ventricular size

Question 16

What are the genetic/ breed predispositions of an Arrhythmogenic right ventricular cardiomyopathy?

Answer 16

• Middle aged boxers, rarely cats
• striatin gene mutation

Question 17

What effect does an Arrhythmogenic right ventricular cardiomyopathy have on the cardiac cycle?

Answer 17

• Ventricular arrythmia, typically left bundle branch block morphology

Question 18

How does hyperthyroidism in cats lead to thyrotoxic heart disease?

Answer 18

• Excessive circulating thyroid hormones
• increased production of myocardial proteins -> hypertrophy, enhanced contractility
• increased calcium recycling. upregulation of receptors, enhanced depolarisation

Question 19

What is Brain-Heart Syndrome?

Answer 19

• Multifocal myocardial necrosis associated with neurological disease of diverse origin

Question 20

When does multifocal myocardial necrosis occur?

Answer 20

• occurs in dogs with gastric torsion, acute necrotising pancreatitis, septic peritonitis

Question 21

What is the nutritional cause of myocardial necrosis?

Answer 21

Vitamin E/ Selenium deficiency

Question 22

How does vitamin E deficiciency cause myocardial necrosis?

Answer 22

• Decreased free-radical scavenging
• free-radical damage to myocyte cell membranes
• myocyte necrosis and mineralisation
• death via ventricular arrythmia

Question 23

What does vitamin E dediciency cause in lambs, calves, foals and camelids

Answer 23

White lamb disease

Question 24

What does vitamin E deficiency cause in Piglets?

Answer 24

Mulberry heart disease

Question 25

What essential amino acid in cats can cause myocardial necrosis?

Answer 25

Taurine
cause taurine-deficiency myocardial failure

Question 26

What stain do we use for taurine-deficiency myocardial failure?

Answer 26

Masson’s Trichrome stain;

Question 27

What plants can cause myocardial necrosis?

Answer 27

Cardiac glycosides e.g foxglove, milkweed, lily of the valley

Question 28

What pharmaceuticals can cause myocardial necrosis?

Answer 28

• Digoxin
• Ionophores
• Chemotherapeutics

Question 29

What beetle may cause myocardial necrosis?

Answer 29

• Blister beetles
• Cantharidin is the toxic principle, it also causes ulcerative gastroenteritis

Question 30

What is the mechanism of action for Digoxin?

Answer 30

Reversibly inhibits Na+/K+ ATPase pump → ↑ intracellular
Na+ and Ca2+ → ↑ inotropy (contractility) but can also
lead to cardiomyocyte necrosis

increased intracellular calcium increases contractility

Question 31

What is the mechanism of action of Ionophore toxins?

Answer 31

• forms reversible complexes with cations and facilitates ionic transport across biological membranes

Question 32

What are the 5 different types of myocarditis?

Answer 32

• Necrotising
• suppurative
• Pyogranulomatous
• Lymphoplasmacytic
• Eosinophillic

Question 33

What problems in dogs predispose to multifocal myocardial necrosis?

Answer 33

• gastric torsion
• acute necrotisisng pancreatitis
• septic peritonitis

Question 34

What is the myocardial response to injury?

Answer 34

• Extensive or minor fibrosis depedning on the extent of the injury?