Lecture 29

Question 1

adverse effects of: necrosis, inflammation, neoplasia, or myocardial degeneration on cardiac funtion(2)

Answer 1

reparative fibrosis if animal survives

depression of myocardial contractility and/or arrhythmia->cardiogenic shock or CHF

Question 2

most common cause of cardiac arrhythmia/dysrhythmia

Answer 2

occur secondary to myocardial damgae

Question 3

potential causes of hydropic or fatty degeneration of cardiac myofibers

Answer 3

systemic diseases, severe anemias, toxemias

Question 4

brown atrophy

Answer 4

sever intra cellular accumulation of lipofuscin pigment

aged animals, especiallly high producing dairy cattle

Question 5

2 main forms of tissue mineralization

Answer 5

dystrophic-in necrotic tissue (eg Johnes disease)

metastatic- in live tissue, high [ ] of Ca or phosphate in circulation (eg Vit D toxicity)

Question 6

when is capacity for division of cardiac myofibers lost

Answer 6

decreased in late fetal life and lost in early neonatal period

Question 7

where are foci of myocardial necrosis most likely to be found in heart

Answer 7

left ventricle- subendocardial myocardium of IC septum and in the papillary muscles

Question 8

how long must patient survive for lesions of necrosis of cardiac myofibers to be grossly obvious? What gross lesions are seen

Answer 8

4-12 hours- areas of subtle pallor

18-24 hours- necrotic zone pale, thin film of fibrin and hemorrhage

Question 9

how are foci of myocardial necrosis repaired

Answer 9

necrotic tissue replaced by fibrosis at 7 days->gross cream white pallor

Question 10

agents responsible for myocardial necrosis(5)

Answer 10

ischemia/hypoxia
excess catecholamines
nutritional deficiency (vit e)
drugs/chemical toxins
plants

Question 11

how long can cardiac myofibers tolerate hypoxic conditions

Answer 11

20-30 minutes->irreversible damage

Question 12

Why is myocardial infarction so common in humans

Answer 12

atherosclerosis (plaque build up) and systemic hypertension

Question 13

examples of causes of myocardial hypoxic/ischemic injury

Answer 13

anemia
hypovolemic shock
thrombosis or coronary artery

Question 14

5 plants that can cause myocardial necrosis

Answer 14

foxglove
capetulip
shaggy pea
african succulents
nerium oleander

Question 15

etiopathogenesis of white muscle disease

which species

Answer 15

lipoperoxidation of striated myofiber membranes->cytoplasmic influx of Ca->ATP consumption to move Ca away from contractile myosin/actin and into SR->mitochondrial damage and Ca induced hypercontraction with segmental degeneration and dystrophic mineralization
in lambs and calves

Question 16

Gross lesion expected with white muscle disease

Answer 16

muscle appears pale, flabby and wet, poor rigor mortis, chalky white grit from mineralization

Question 17

cardiac lesion of mulberry heart disease in pigs(2)

Answer 17

multifocal to diffuse hemorrhage in epicardium, myocardium and subendocardium
patchy myocardial pallor due to multifocal necrosis

Question 18

some potential causes of myocarditis

Answer 18

parvo, distemper (virus)
actinbacillus equuli, blackleg (bacteria)
protozoa (toxoplasma gondii)
helminths (cestode)

Question 19

cardiomyopathy

Answer 19

idiopathic myocardial disease

diagnosed by exclusion of other possible causes

Question 20

gross characteristics of hypertrophic cardiomyopathy?
major effect on function?
which species?

Answer 20

cardiomegaly with prominent concentric hypertrophy of LV and IV septum
myocardial contractility inc or normal, but filling is dec
common in cats

Question 21

gross characteristics of DCM?
major effect on function?
species?

Answer 21

dec contractility, inc EDV, and dec ventricular ejection
all chambers dilated but LA and LV obvious
common in dogs

Question 22

effect of restrictive cardiomyopathy on function?
species?
What is physically responsible?

Answer 22

marked LA enlargement due to impaired LV filling
cats
stiffness, dec ventricular compliance and impaired diastolic filling of LV

Question 23

common consequence of cardiomyopathy in cats?

clinical signs?

Answer 23

thromboembolism->LA->distal aortic trifurcation(saddle)

sudden onset of uni or bilateral paralysis with absence of femoral pulse

Question 24

neoplasms that can involve heart in dogs? most common?

Answer 24

hemangiosarcoma
lymphoma(most common)-multinodular white cream nodules or diffuse pallor
mast cell tumor

Question 25

tumors that commonly involve heart in ruminants

Answer 25

peripheral nerve sheath tumor