Canine dilated cardiomyopathy (Yr 4) Flashcards
what is a cardiomyopathy?
disorder in which the heart muscle in structurally and functionally abnormal
what is the most common primary cardiomyopathy?
dilated cardiomyopathy (DCM)
what dogs present with DCM?
adult large breed dogs (dobermans)
what is the prognosis for DCM?
guarded (CHF or sudden death)
what is the overall effect of DCM?
impaired systolic function
dilated cardiac chambers (thin walls)
what is the aetiology of DCM?
idiopathic
secondary (DCM like phenotypes)
genetics (mutations)
what is the gross pathology of DCM?
dilation of all four heart chambers (with the left ventricle being the worst effected) - football
thin walls
mitral/tricuspid annulus stretch
why can DCM cause mitral regurgitation?
dilation of the heart chambers causes stretch of mitral/tricuspid annulus (valve pulled apart)
what type of hypertrophy occurs in DCM?
eccentric
what are the histopathological findings on DCM?
atrophied fibres - thin myocytes, degeneration, fibrosis
what part of the heart is diseased in DCM?
walls
what is the first thing that happens in DCM?
poor systolic function
what is the pathogenesis of DCM?
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
what are the effects of the systemic nervous system activation due to reduced cardiac output in DCM?
tachycardia
positive inotrope
vasoconstriction (increases afterload)
these three increase oxygen demand of heart and lead to cell death
what are the effects of the RAAS activation due to reduced cardiac output in DCM?
retention of sodium and fluid
increased circulatory volume which increases hydrostatic pressure
vasoconstriction
what are the similarities between DCM and MDVD?
enlargement of left ventricle (and right)
enlarged left atrium
mitral regurgitation
what are the differences between MDVD and DCM?
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)
what breeds are predisposed to DCM?
dobermans
(Great Danes, Irish wolfhound, spaniels)
what is often the first presentation of DCM in dobermans?
sudden death
what can predispose cocker spaniels to DCM?
taurine deficiency
what breed get DCM as a juvenile?
Portuguese water dogs
what breeds are predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC)?
boxers
(English bulldogs)
what is the gross pathology seen with ARVC?
right ventricular dilation (and wall thinning)
what are the three possible presentations of ARVC?
asymptomatic with VPCs
symptomatic with VPCs
ventricular dilation, myocardial dysfunction, arrhythmias (structural change)
what age do dogs get ARVC?
adult onset (inherited)
what breeds are predisposed to atrial cardiomyopathy?
English springer spaniel
labradors
what is the gross pathology of atrial cardiomyopathy?
dilated left atrium and thin atrial walls
what rhythm can be seen with dogs that have atrial cardiomyopathy?
atrial standstill
what is the treatment for atrial cardiomyopathy?
pacemaker
what breeds of dog are predisposed to hypertrophic cardiomyopathy?
terriers, pointers, retrievers
(rare in dogs, usually seen in cats)
what are some secondary cardiomyopathy that present like DCM (DCM-like phenotype)?
myocarditis
tachycardia induced cardiomyopathy
taurine deficiency
what is the typical presentation of a DCM dog?
large adult breeds (doberman)
quiet soft, left apical systolic heart murmur
arrhythmia
dyspnoea, tachypnoea, crackles (CHF)
how does the murmur associated with DCM differ to MDVD?
DCM is a quiet left apical systolic murmur
MDVD is a loud left apical systolic murmur
is collapse and sudden death more common in DCM or MDVD?
DCM
what clinical pathology can be done for DCM cases?
troponin - cardiomyocte damage
NT-proBNP - wall stretch
why might DCM cases have hypotension?
forward failure due to systolic dysfunction (not contracting as well)
what arrhythmias can be seen tih DCM?
atrial fibrillation
VPCs
SVPCs
ventricular tachycardia
if a dog with DCM has sinus arrhythmia are they in congestive heart failure?
no
how do DCM hearts present on radiographs?
very large (footballs or very tall)
how does DCM appear on echocardiography?
enlarged left ventricle and atrium
dilated left ventricle (bullet shape)
round left ventricle
reduced systolic function
mild mitral regurgitation
what therapy is used for preclinical DCM?
pimobendan (prolongs onset of CHF)
what treatment is used when DCM cases go into CHF?
furosemide
pimobendan
ACE-inhibitor
spironolactone
if a preclinical DCM case is on pimobendan and then goes into CHF, what therapy will they go onto?
furosemide (normal CHF drugs)
