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)