Test 1: lecture 9 mitral valve Flashcards
cavilers have what heart issue
mitral valve disease
mitral valve disease makes up —% of canine cardiac disease
75-80%
more common in small dogs
Cavalier King Charles Spaniel
no sex predilection
the chordea tendinea are made of
fibrosa layer of mitral valve
dense collagen fibers
layers of the mitral valve
what happens to valve with myxomatous mitral valve
fibrosa layer becomes smaller/degrades
spongiosa layer thickens
endothelial layer forms nodules
most dogs with mild MVD will —
never have clinical signs
not have CHF (they will be fine)
mitral valve disease
nodular valve
jet lesion in atria
ruptured chordea tendinea
what cell causes damage to mitral valve
valvular interstitial cell
will get turned on and degrade fibrosa layer and cause nodules in endothelial layer
activated by stress, age and injury
convert to myofibroblast phenotype (remodel ECM to MVD)
how does MVD effect kidney
lower stroke volume= lower renal perfusion
kidney will increase RAAS and cause increased LV volume
this leads to LV eccentric hypertrophy (thin walls big volume)
which leads to increased pulmonary venous pressure and CHF
what causes MVD
we dont really know
BUT NOT INFECTIOUS
what kind of murmur will MVD cause
left sided systolic apical
can be soft- thrilling
false positive murmur
loud murmur but mild disease
false negative murmur
soft murmur with severe disease
how to predict how bad MVD is
clinical signs: exercise intolerance, fainting, dyspnea
EKG: errhythmias
XRays- large heart= bad, CHF or pulomonary venous distension
Echo: volume overload, thickened and prolapse valve
EKG changed for mitral valve disease
wide P wave: Left atrial enlargment
Tall R waves: LV enlargment
wide QRS: LV enlargment
APC or VPCs can occur
Afib can happen with severe atrial enlargement
xray of dogs with MVD will show
big heart
LA,LV enlargement
pulmonary venous distension
perihilar interstital/alveolar (CHF/edema)
echo of MVD will show
thickened valve leaflets
prolapse
ruptured chordae tenineae
regurg into the left atrium (jet lesion)
4 stages of MVD
A: no disease, but at risk
B: MVD but no clinical signs
B1: no heart enlargement
B2: heart enlargement
C: MVD, CHF and on meds
D: MVD advanced disease, refractory clinical signs
Stage A MVD
no disease but at risk based on breed
Stage B MVD
MVD present, but no clinical signs
Stage B1 MVD
MVD with no clinical signs and no cardiac enlargement
Stage B2 MVD
MVD with no clinical signs but + cardiac enlargement
Stage C MVD
MVD present, CHF, on meds
Stage D MVD
MVD present, advanced disease, refractory clinical signs
how to treat stage B2 MVD
pimobendan
(ACEI)
can slow down disease, keeps them asymptomatic longer
differential for MVD: cough and murmur
primary respiratory disease: COPD, Asthma, allergic bronchitis, collapsing trachea
Xray will have NO heart enlargment
how to treat acute CHF therapy for MVD
FOND
furosemide (preload)
oxygen
nitro (pre/afterload)
dobutamine (inotropy)
how to treat chronic CHF therapy for MVD
FASP
furosemide (preload)
ACT inhibitor (decreases RAAS)
pimobendan
spironolactone
enalapril will do — with MVD
will not delay onset of heart failure in stage B MVD
primobendan given to stage B2 MVD will do
give 15 extra months with no CHF symptoms
MVD complications
left atrial tear from jet lesion (leads to pericardial effusion)
ruptured chordae tendinae
arrhythmias (Afib, APC, VPC)
