Canine dilated cardiomyopathy (Yr 4) Flashcards

1
Q

what is a cardiomyopathy?

A

disorder in which the heart muscle in structurally and functionally abnormal

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2
Q

what is the most common primary cardiomyopathy?

A

dilated cardiomyopathy (DCM)

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3
Q

what dogs present with DCM?

A

adult large breed dogs (dobermans)

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4
Q

what is the prognosis for DCM?

A

guarded (CHF or sudden death)

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5
Q

what is the overall effect of DCM?

A

impaired systolic function
dilated cardiac chambers (thin walls)

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6
Q

what is the aetiology of DCM?

A

idiopathic
secondary (DCM like phenotypes)
genetics (mutations)

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7
Q

what is the gross pathology of DCM?

A

dilation of all four heart chambers (with the left ventricle being the worst effected) - football
thin walls
mitral/tricuspid annulus stretch

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8
Q

why can DCM cause mitral regurgitation?

A

dilation of the heart chambers causes stretch of mitral/tricuspid annulus (valve pulled apart)

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9
Q

what type of hypertrophy occurs in DCM?

A

eccentric

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10
Q

what are the histopathological findings on DCM?

A

atrophied fibres - thin myocytes, degeneration, fibrosis

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11
Q

what part of the heart is diseased in DCM?

A

walls

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12
Q

what is the first thing that happens in DCM?

A

poor systolic function

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13
Q

what is the pathogenesis of DCM?

A

impaired systolic function
reduced cardiac output
sympathetic nervous system and RAAS activated
increased HR/contractility and myocardial hypertrophy
increased myocardial oxygen demand and wall stress to maintain cardiac output
myocardial cell death and fibrosis
this further impairs systolic function

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14
Q

what are the effects of the systemic nervous system activation due to reduced cardiac output in DCM?

A

tachycardia
positive inotrope
vasoconstriction (increases afterload)
these three increase oxygen demand of heart and lead to cell death

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15
Q

what are the effects of the RAAS activation due to reduced cardiac output in DCM?

A

retention of sodium and fluid
increased circulatory volume which increases hydrostatic pressure
vasoconstriction

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16
Q

what are the similarities between DCM and MDVD?

A

enlargement of left ventricle (and right)
enlarged left atrium
mitral regurgitation

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17
Q

what are the differences between MDVD and DCM?

A

mild mitral regurgitation in DCM (severe in MDVD)
DCM has reduced systolic function but MDVD has normal/hyperdynamic systolic function
DCM the left ventricle enlarges more than the atrium (opposite in MDVD)

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18
Q

what breeds are predisposed to DCM?

A

dobermans
(Great Danes, Irish wolfhound, spaniels)

19
Q

what is often the first presentation of DCM in dobermans?

A

sudden death

20
Q

what can predispose cocker spaniels to DCM?

A

taurine deficiency

21
Q

what breed get DCM as a juvenile?

A

Portuguese water dogs

22
Q

what breeds are predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC)?

A

boxers
(English bulldogs)

23
Q

what is the gross pathology seen with ARVC?

A

right ventricular dilation (and wall thinning)

24
Q

what are the three possible presentations of ARVC?

A

asymptomatic with VPCs
symptomatic with VPCs
ventricular dilation, myocardial dysfunction, arrhythmias (structural change)

25
Q

what age do dogs get ARVC?

A

adult onset (inherited)

26
Q

what breeds are predisposed to atrial cardiomyopathy?

A

English springer spaniel
labradors

27
Q

what is the gross pathology of atrial cardiomyopathy?

A

dilated left atrium and thin atrial walls

28
Q

what rhythm can be seen with dogs that have atrial cardiomyopathy?

A

atrial standstill

29
Q

what is the treatment for atrial cardiomyopathy?

A

pacemaker

30
Q

what breeds of dog are predisposed to hypertrophic cardiomyopathy?

A

terriers, pointers, retrievers
(rare in dogs, usually seen in cats)

31
Q

what are some secondary cardiomyopathy that present like DCM (DCM-like phenotype)?

A

myocarditis
tachycardia induced cardiomyopathy
taurine deficiency

32
Q

what is the typical presentation of a DCM dog?

A

large adult breeds (doberman)
quiet soft, left apical systolic heart murmur
arrhythmia
dyspnoea, tachypnoea, crackles (CHF)

33
Q

how does the murmur associated with DCM differ to MDVD?

A

DCM is a quiet left apical systolic murmur
MDVD is a loud left apical systolic murmur

34
Q

is collapse and sudden death more common in DCM or MDVD?

A

DCM

35
Q

what clinical pathology can be done for DCM cases?

A

troponin - cardiomyocte damage
NT-proBNP - wall stretch

36
Q

why might DCM cases have hypotension?

A

forward failure due to systolic dysfunction (not contracting as well)

37
Q

what arrhythmias can be seen tih DCM?

A

atrial fibrillation
VPCs
SVPCs
ventricular tachycardia

38
Q

if a dog with DCM has sinus arrhythmia are they in congestive heart failure?

A

no

39
Q

how do DCM hearts present on radiographs?

A

very large (footballs or very tall)

40
Q

how does DCM appear on echocardiography?

A

enlarged left ventricle and atrium
dilated left ventricle (bullet shape)
round left ventricle
reduced systolic function
mild mitral regurgitation

41
Q

what therapy is used for preclinical DCM?

A

pimobendan (prolongs onset of CHF)

42
Q

what treatment is used when DCM cases go into CHF?

A

furosemide
pimobendan
ACE-inhibitor
spironolactone

43
Q

if a preclinical DCM case is on pimobendan and then goes into CHF, what therapy will they go onto?

A

furosemide (normal CHF drugs)

44
Q
A