Cardio 3 Flashcards

1
Q

You are performing a necropsy on a horse that died acutely of heart failure. You note large areas of pallor and mottling in the ventricular myocardium. Which toxin is most likely responsible for this? And how would the horse have gained access?

A

An ionophore such as monensin should be high in your differential list. Ionophores are extremely toxic to horses, even at low doses. Horses typically gain access through access to ruminant feed (grain bin or feeding trough raids), through horse feed accidentally mixed with ruminant feed, or through horse feed contaminated with ionophores in a mill producing poultry, cattle, and horse feeds.

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2
Q

You are performing a necropsy on a dog and notice roughened, firm, gritty plaques on the ventricular and atrial endocardium and along the tunica intima of great vessels. What are some of your potential diagnoses?

A

This is endocardial mineralization. In dogs the potential diagnoses include: (1) excess vitamin D from rodenticide toxicity; (2) metastatic calcification caused by hypercalcemia of malignancy.

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3
Q

Which types or breeds of dog are predisposed to myxomatous valvular degeneration (endocardiosis)?

A

Small and medium breeds, especially cavalier King Charles spaniels

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4
Q

Canine myxomatous valvular degeneration (endocardiosis) could be expected to have associated atrial dilation. True or false? Please explain / justify your answer.

A

True. Affected valves are incompetent (leaky), resulting in a jet of blood passing backwards from the ventricle into the atrium with each heart beat. This causes eccentric dilation of the atrium through volume overload.

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5
Q

Canine myxomatous valvular degeneration (endocardiosis) could be expected to have associated ventricular jet lesions. True or false? Please explain / justify your answer.

A

False. Affected valves are incompetent (leaky), resulting in a jet of blood passing backwards from the ventricle into the atrium with each heart beat. This causes turbulence of blood within the ATRIUM (not ventricle) and trauma to the ATRIAL endocardium. Chronically this results in endocardial proliferation and fibrosis, manifesting as streaks, wrinkles and roughening or “jet lesions.” These are found in the atrium, not the ventricle.

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6
Q

Which domestic animal species is most predisposed to development of myxomatous valvular degeneration (endocardiosis)?

A

Dogs

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7
Q

Deficiency of which substance is the most common cause of nutritional myocardial necrosis in calves and lambs? And what is the lay term for this disease?

A

Vitamin E or selenium. “White muscle disease.”

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8
Q

What gross cardiac lesion may be produced by all three of the following conditions: (1) septicemias, especially those with endotoxins; (2) electrocution and anoxia; (3) agonal change at death?

A

Endocardial and epicardial hemorrhage. Remember that the endocardial and epicardial hemorrhage caused as an agonal change at death is a non-significant lesion, which should be ignored.

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9
Q

Explain the difference between endocardiosis and endocarditis.

A

Endocardiosis is caused by degeneration of collagen in atrioventricular valves. In endocardiosis: the cusps of the atrioventricular valves are shortened, nodular, and SMOOTH.
Endocarditis is caused by bacterial colonization of valve cusps, predisposed to by bacteremias and turbulent blood flow. In endocarditis affected valve cusps have large, friable, grey-yellow masses or “vegetations” that, chronically, may become wart-like. Their ROUGH surfaces are distinct from the smooth surfaces of valves with endocardiosis.

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10
Q

Explain the pathogenesis whereby a subcutaneous abscess in a cow may lead to severe heart disease.

A

Abscess -> invasion into tissues -> bacteria released to circulation -> bacteremia -> formation of bacterial vegetations on heart valves or (less commonly) showering of myocardium via coronary arteries -> heart disease

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11
Q

What are three reasons why cardiac endocardial and epicardial hemorrhage could be present at necropsy?

A

(1) Septicemias, especially those with endotoxins; this is a true lesion; (2) Electrocution or anoxia; this is a true lesion; (3) Agonal change at death; this is a non-significant lesion, which should be ignored

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12
Q

Dilated cardiomyopathy is the most common cause of congestive heart failure in dogs. True or false?

A

False. Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in dogs.

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13
Q

Explain the key gross difference between the cause of valvular endocardiosis versus the cause of valvular endocarditis.

A

Endocardiosis is caused by degeneration of collagen in atrioventricular valves.
Endocarditis is caused by bacterial colonization of valve cusps, predisposed to by bacteremias and turbulent blood flow.

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14
Q

What are three possible broad causes of endocardial mineralization?

A

(1) Excess vitamin D intake: calcinogenic plants in grazing animals or rodenticide toxicity in dogs; (2) Granulomatous disease: Johne’s disease in ruminants; (3) Hypercalcemia of malignancy (i.e., metastatic calcification)

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15
Q

What is another name for an aortic body tumor?

A

A chemodectoma. The aortic body is one of several small clusters of peripheral chemoreceptors, baroreceptors, and supporting cells located along the aortic arch.

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16
Q

Canine myxomatous valvular degeneration (endocardiosis) leads to which type of cardiac hypertrophy: concentric or eccentric? And why?

A

Eccentric hypertrophy. This type of hypertrophy results from VOLUME overload, as is seen when valves are incompetent and allow blood to move backwards as well as forwards.

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17
Q

Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in cattle. True or false?

A

False. Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in DOGS.

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18
Q

What s the term for a MALIGNANT tumor arising from the cells of the myocardium?

A

Cardiac rhabdomyosarcoma (Note that the term rhabdomyosarcoma means a malignant tumor of ANY striated muscle. It is not particular to the heart, and could also apply to any skeletal muscle in the body. Hence the “cardiac” part of cardiac rhabdomyosarcoma.)

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19
Q

Which heart valves (atrioventricular, pulmonic, or aortic) are most commonly affected by myxomatous valvular degeneration (endocardiosis)?

A

Atrioventricular valves. Left AV (mitral) valve [66% of cases] > Right AV (tricuspid) valve [33% of case]&raquo_space;> Aortic or pulmonic valves [rare]

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20
Q

In which domestic animal species is heart failure caused by ruptured chordae tendineae most common?

A

Horses

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21
Q

Describe the characteristic gross appearance of cardiac lesions caused by Clostridium chauvoei in cattle.

A

Severe necrohemorrhagic myocarditis, possibly with areas of crepitus caused by gas bubble formation.

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22
Q

What is a chemodectoma?

A

A neoplasm of the aortic body. The aortic body is one of several small clusters of peripheral chemoreceptors, baroreceptors, and supporting cells located along the aortic arch.

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23
Q

Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in dogs. True or false?

A

True. Small and medium breeds, especially cavalier King Charles spaniels, are predisposed.

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24
Q

What s the term for a BENIGN tumor arising from the cells of the myocardium?

A

Cardiac rhabdomyoma (Note that the term rhabdomyoma means a benign tumor of ANY striated muscle. It is not particular to the heart, and could also apply to any skeletal muscle in the body. Hence the “cardiac” part of cardiac rhabdomyoma.)

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25
Q

You are performing a necropsy on a dog and notice roughened, firm, fibrous “streaks” on the left atrial endocardium. What is the most likely diagnosis for this and what is the pathogenesis?

A

These are “jet lesions”, where an incompetent (leaking) left AV valve has resulted in a jet of blood passing backwards from the left ventricle into the left atrium with each heart beat. This causes turbulence of blood within the left atrium and trauma to the endocardium. Chronically this results in endocardial proliferation and fibrosis, manifesting as streaks, wrinkles and roughening.

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26
Q

You are performing a necropsy on a dog and notice roughened, firm, fibrous “streaks” on the right atrial endocardium. What is the most likely diagnosis for this and what is the pathogenesis?

A

These are “jet lesions”, where an incompetent (leaking) right AV valve has resulted in a jet of blood passing backwards from the right ventricle into the right atrium with each heart beat. This causes turbulence of blood within the right atrium and trauma to the endocardium. Chronically this results in endocardial proliferation and fibrosis, manifesting as streaks, wrinkles and roughening.

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27
Q

Which parvoviral syndrome is more common in young dogs aged ~6-20 weeks: (a) profuse hemorrhagic diarrhea or (b) sudden unexpected death from heart failure?

A

(a) Profuse hemorrhagic diarrhea (i.e., parvoviral hemorrhagic enteritis). Canine parvovirus infects rapidly dividing cells, which in dogs of this age are primarily the epithelial lining cells of the small intestine (enterocytes). By this age cardiac myocytes are no longer dividing and so are resistant to CPV infection.

28
Q

Canine myxomatous valvular degeneration (endocardiosis) could be expected to have associated atrial jet lesions. True or false? Please explain / justify your answer.

A

True. Affected valves are incompetent (leaky), resulting in a jet of blood passing backwards from the ventricle into the atrium with each heart beat. This causes turbulence of blood within the atrium and trauma to the endocardium. Chronically this results in endocardial proliferation and fibrosis, manifesting as streaks, wrinkles and roughening or “jet lesions.”

29
Q

What are the two most common metastatic tumors of the canine heart?

A

Hemangiosarcoma and lymphoma

30
Q

Describe the cardiac lesions in a young puppy that died unexpectedly from heart failure caused by canine parvoviral myocarditis.

A

The heart is pale and flaccid and the ventricular myocardium contains extensive coalescing areas of pallor.

31
Q

Describe the gross appearance of a canine heart valve affected by myxomatous valvular degeneration (endocardiosis).

A

The cusps of the atrioventricular valves are shortened, nodular, and smooth. The smoothness distinguishes this disease from the roughed valves seen in endocarditis.

32
Q

A chemodectoma is a neoplasm of the aortic body. What, and where, is the “aortic body”?

A

The aortic body is one of several small clusters of peripheral chemoreceptors, baroreceptors, and supporting cells located along the aortic arch.

33
Q

Describe the characteristic gross appearance of cardiac lesions of histophilosis in cattle.

A

Dry, pale areas of necrosis in the ventricular myocardium. Lesions are often found in the longitudinally sectioned ventricular papillary muscle. This is a characteristic location in the heart for histophilosis lesions. [Remember the “boxing glove” cut.]

34
Q

Which bacterial species (also causing thrombotic meningoencephalitis) commonly causes myocarditis in cattle?

A

Histophilus somni

35
Q

Where are two good locations to look for the lesions of “white muscle disease” in neonatal calves and lambs? And why?

A

The heart and tongue. These are the hardest working muscles in a neonate and so are the first to show degenerative myonecrosis caused by vitamin E or selenium deficiency.

36
Q

Explain the pathogenesis whereby a dental cleaning procedure in a cat may lead to severe heart disease.

A

Dental procedure -> gingival trauma -> gingival bacteria released to circulation -> bacteremia -> formation of bacterial vegetations on heart valves or (less commonly) showering of myocardium via coronary arteries -> heart disease

37
Q

Sometimes during necropsy examination of the heart the chordae tendineae are inadvertently cut by 4th year rotation students (never by pathologists). Why would you not misdiagnose these as ruptured chordae tendineae?

A

Real ruptured chordae tendineae have swollen, rounded and sometimes hemorrhagic tips. Chordae tendineae that were cut after death have sharp (not rounded) cut surfaces, a normal diameter (no swelling) and no hemorrhage. These are the same principles that apply to determining if any organ was cut before or after death.

38
Q

You are performing a necropsy on a horse that died of heart failure. You note that (a) several of the chordae tendineae of the left AV valve are broken and have swollen and hemorrhagic tips, and (b) the endocardial and epicardial surfaces have scattered areas of hemorrhage. What is the significance of lesions (a) and (b)?

A

(a) These are ruptured chordae tendineae, which are very significant and are likely responsible for this horses heart failure and death.
(b) These are agonal hemorrhages that commonly occur as an animal dies; they are non-significant lesions, which should be ignored (after ruling out significant causes such as septicemia or electrocution).

39
Q

What is a cardiac rhabdomyosarcoma?

A

A MALIGNANT tumor arising from the striated muscle cells of the myocardium.

40
Q

Why are the lesions of “white muscle disease” in neonatal calves and lambs most commonly detected in the heart and tongue?

A

These are the hardest working muscles in a neonate and so are the first to show degenerative myonecrosis caused by vitamin E or selenium deficiency.

41
Q

Describe the characteristic gross cardiac lesions of nutritional myocardial necrosis in neonatal calves and lambs.

A

On section the ventricular myocardium has areas of pallor (fibrosis) or pallor, dryness and grittiness (dystrophic mineralization). The ventricular papillary muscles and ventricular subendocardial (i.e., “inner”) myocardium are typically the hardest hit.

42
Q

Explain the pathogenesis whereby a hepatic abscess in a cow may lead to severe heart disease.

A

Hepatic abscess -> invasion into blood vessels walls -> bacteria released to circulation -> bacteremia -> formation of bacterial vegetations on heart valves or (less commonly) showering of myocardium via coronary arteries -> heart disease

43
Q

Ionophores such as monensin are potential cardiotoxins, yet are routinely added to animal feed. Which domestic animal species is most sensitive to the cardiotoxic effects of ionophores?

A

Horses.

44
Q

In which domestic species is hemagiosarcoma the most common primary neoplasm?

A

Dog

45
Q

What is the most common primary neoplasm of the heart in dogs?

A

Hemangiosarcoma

46
Q

Canine myxomatous valvular degeneration (endocardiosis) most commonly affects the … [choose one]:
(a) aortic and pulmonic valves
(b) atrioventricular valves
(c) left-sided heart valves
(d) right-sided heart valves

A

(b) atrioventricular valves

47
Q

Bacterial vegetations on heart valves may shower the myocardium, leading to bacterial myocarditis. Outline the route taken by showered bacteria that cause this.

A

Vegetation on LEFT-sided heart valve (aortic or mitral/LAV) -> left heart chambers -> aorta -> coronary arteries -> seed myocardium -> myocarditis

48
Q

Explain the key gross difference between lesions of valvular endocardiosis and valvular endocarditis.

A

Endocardiosis: the cusps of the atrioventricular valves are shortened, nodular, and SMOOTH.
PLEASE NOTE THAT AT THIS POINT ONLY HALF THE ANSWER REQUIRED HAS BEEN PROVIDED. THE REMAINDER IS BELOW. PLEASE REMEMBER TO FINISH YOUR ANSWERS IN EXAMS.
Endocarditis: affected valve cusps have large, friable, grey-yellow masses or “vegetations” that, chronically, may become wart-like. Their ROUGH surfaces are distinct from the smooth surfaces of valves with endocardiosis.

49
Q

Which parvoviral syndrome is more common in young puppies aged <4 weeks: (a) profuse hemorrhagic diarrhea or (b) sudden unexpected death from heart failure?

A

(b) Sudden unexpected death from heart failure (i.e., parvoviral myocarditis). Canine parvovirus infects rapidly dividing cells, which in neonatal puppies up to ~ 15days old includes cardiac myocytes. After this age cardiac myocytes are no longer dividing and so are resistant to CPV infection.

50
Q

You are performing a necropsy on a young puppy that died unexpectedly from heart failure. The heart is pale and flaccid and you note several extensive coalescing areas of pallor in the ventricular myocardium. What is the most likely diagnosis?

A

Canine parvoviral myocarditis

51
Q

Which canine heart valve is most commonly affected by myxomatous valvular degeneration (endocardiosis)?

A

The left atrioventricular valve. Left AV (mitral) valve [66% of cases] > Right AV (tricuspid) valve [33% of case]&raquo_space;> Aortic or pulmonic valves [rare]

52
Q

Deficiency of which substance is the most common cause of nutritional myocardial necrosis in pigs? And what is the lay term for this disease?

A

Vitamin E or selenium. “Mulberry heart disease.”

53
Q

What is a cardiac rhabdomyoma?

A

A BENIGN tumor arising from the striated muscle cells of the myocardium.

54
Q

Vegetative valvular endocarditis most commonly affects the … [choose one]:
(a) aortic and pulmonic valves
(b) atrioventricular valves
(c) left-sided heart valves
(d) right-sided heart valves

A

(c) left-sided heart valves: mitral and aortic

55
Q

You are performing a necropsy on a cow and notice roughened, firm, gritty plaques on the ventricular and atrial endocardium and along the tunica intima of great vessels. What are some of your potential diagnoses?

A

This is endocardial mineralization. In cattle the potential diagnoses include: (1) excess vitamin D intake from grazing on calcinogenic plants such as Solanum species; (2) granulomatous disease such as Johne’s disease; (3) metastatic calcification caused by hypercalcemia of malignancy.

56
Q

Myxomatous valvular degeneration is the same as … [choose one]:
(a) Endocardiosis
(b) Endocarditis

A

(a) Endocardiosis

57
Q

What are three possible broad causes of endocardial fibrosis?

A

(1) “Jet lesions” due to turbulent blood flow caused by incompetent valves; (2) Chronic cardiac dilation, such as seen with dilated cardiomyopathy; (3) Secondary to healed endocardial ulceration, usually due to uremia.

58
Q

What is the precise predilection site for development of cardiac hemangiosarcoma in dogs?

A

The right auricle or atrium

59
Q

You are performing a necropsy on a horse and notice roughened, firm, gritty plaques on the ventricular and atrial endocardium and along the tunica intima of great vessels. What are some of your potential diagnoses?

A

This is endocardial mineralization. In horses the potential diagnoses include: (1) excess vitamin D intake from grazing on calcinogenic plants such as Solanum species; (2) metastatic calification caused by hypercalcemia of malignancy.

60
Q

Which bacterial species (more commonly causing necrohemorrhagic myositis of skeletal muscle or “blackleg”) sometimes causes myocarditis in cattle?

A

Clostridium chauvoei [please pay attention to spelling]

61
Q

Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in cats. True or false?

A

False. Myxomatous valvular degeneration (endocardiosis) is the most common cause of congestive heart failure in DOGS.

62
Q

Which virus is a relatively common cause of myocarditis in very young puppies?

A

Canine parvovirus

63
Q

Which is the most common route of infection for bacterial myocarditis: hematogenous or via lymphocytic trafficking?

A

Hematogenous

64
Q

Ionophores are potential cardiotoxins, yet are routinely added to animal feed. Why are they added to feed for (a) cattle and (b) poultry?

A

Ionophores are used as feed additives to: (a) increase feed efficiency and weight gain in cattle, and (b) control coccidiosis in poultry.

65
Q

The most common route of infection for bacterial myocarditis is via hematogenous spread. What are the two most common sources for this?

A

(1) Systemic bacteremia showering myocardium; (2)
Vegetations on heart valves, where bacterial thromboemboli shower the myocardium via the coronary arteries

66
Q

Do you think endocardiosis is the same as endocarditis?

A

No