Myxomatous Mitral Valve Disease (Borgarelli) Flashcards
Define MMVD
a progressive degernative diease of the mitral valve leaflets + chordae tendinae
due to altered synthesis or remodeling by type IV collagen
MMVD vs Endocarditis
MMVD: a degenerative process of valve
Endocarditis: an inflammatory process of valve
Pathophysiology of MMVD
thickend leaflet edges and thickened + weakened chordae tendinae -> eventual rupture of chordae tendinae and prolapse of leaflets -> mitral valve regurg -> LA dilation -> pulmonary edema
What happens if compensated MMVD does not get surgically repaired?
systole will be negatively affected (decr. contractility => decr. CO)
Signlament for MMVD
small-breed dogs, typically geriatric (cavalier king charles spaniel, dachsunds, toy poodles)
PE findings for MMVD
systolic murmur on left apex, usually radiating toward base and to the right -> confirm on echo
Stage B1 vs B2 of MMVD
Both: dogs with MMVD with no hx of clinical signs
B1: no rads or echo evidence of LH enlargment
B2: YES rads or echo evidence of LH enlargement
When should furosemide be started for MMVD patients?
Stage C - dogs with MMVD and past or current clinical signs of CHF
When may patients benefit from pimobendan +/- spironolactone +/- ACE-I, and also require echo or thx rads for evaluation?
Stage B2
Pimobendan: positive inotrope that increases calcium bonding in myofilaments
Enalapril and Benazepril: ACE-I
Spironolactone: potassium-sparing (increases K retention, increases excess sodium renal excretion (too much sodium in bloodstream = increased capillary oncotic pressure -> water gets pulled into bloodstream -> hypertension)
What is the most common complaint of dogs with MMVD?
Cough due to a concomitant RESPIRATORY dz (and NOT b/c of HF!)
concomitant resp. dz or enlarged LA compressing 1º bronchus
Where are cough receptors located and why does this prove that a cough is of a PRIMARY RESP dz in MMVD dogs?
Cough receptors are located in the primary bronchi, and NOT in the lower bronchioles.
(Pulmonary edema in CHF of MMVD affects the lower bronchioles and only produces shortness of breath)
What grade murmur of MMVD?
> 3/6 (either 4 or 5)
Dog presents for grade 4-5/6 heart murmur, tachypnea (>36 breahts/min), dyspnea, exercise intolerance, and a cough. You treat it with furosemide and the tachypnea/dyspnea resolve after a 24-48h. What is your diagnosis?
Dog in Stage C MMVD that was in heart failure.
Why is afterload decreased in MMVD?
B/c blood in left ventricle has an extra route to leave the ventricle (mitral valve/regurg)
