Cardio/ Resp pt.2 Flashcards
Myxomatous Mitral Valve Degeneration (MMVD)
- degenerative valvular disease leading to valve incompetency, left atrial enlargement, volume overload, and CHF
- also called mitral valve endocardiosis
MMVD (pathology)
- expansion of spongiosa valve layer w/ glycosaminoglycans and proteoglycans
- valve leaflets thicken and roll at edges
- can affect chordae tendineae
- valve may prolapse and leak; chordae may rupture
MMVD (pathophysiology)
- mitral valve regurge leads to L atrial enlargement
- volume overload
- left ventricular enlargement
- elevated LA pressure, pulmonary venous distention
- left-sided congestive herat failure
MMVD compensation
- mitral valve regurge may be compensated for
- MMVD reduces flow to kidneys and activates RAAS
- RAAS increases volume and generates volume overload and eccentric hypertrophy
- inc stretch = inc contraction and systolic function
MMVD (signalment)
- disease of old, small breed dogs
- Cavalier King Charles Spaniels (also will have younger age of onset)
MMVD (physical exam)
- systolic click (high-pitched sound caused by prolapsed MV)
- often cough/ resp distress if CHF present
- L apical systolic regurgitant murmur (severity corresponds to intensity)
MMVD (ECG)
- typical sinus rhythm
- possibly APCs, VPCs, A-fib
- pattern of chamber enlargment (P mitrale, LV enlargement)
MMVD (Chest rads)
- symptomatic dogs have rads consistent with CHF (LA large, pulm venous distension)
MMVD (Echo)
- thickened mitral valve leaflets
- mitral valve regurge
- Left atrial and ventricular distension
- hyperdynamic LV
T/F: the most reliable indication of diseases severity of MMVD is LA size
T
ABP impacts on MMVD
- systemic pressure elevation worsens MMVD
- slight reduction in systemic pressures can reduce regurgitant fraction
- use of amlodipine is a useful stretegy for managing MMVD
MMVD (therapy prior to CHF)
- Pimobendan
- Enalapril/ Benazapril
MMVD (prognosis)
- 15 months from stage B2 to CHF with pimobendan
MMVD (therapy post CHF)
- diuretics (furosemide)
- ace-inhibitors (enalapril, benaazapril)
- pimobendan
- spirinolactone
- low salt diet
- amlodipine if hypertensive
- diltiazem +/- digoxin if a-fib
DIlated Cardiomyopathy
- heart muscle disease with characteristic systolic dysfunction and ventricular dilation (eccentric hypertrophy)
- can affect both, but mainly left
DCM ( Etiology)
- familial/ genetic
- nutritional
- viral
- metabolic
–> DCM appearance is the same regardless of etiology
DCM (Signalment)
- large breed dogs
- doberman is classic
DCM (pathogenesis)
- reduced cardiac output
- RAAS activation
- Na and H2O retention, vasoconstriction, cardiac remodeling
- further reduction in heart function
- increased preload
- progression of disease, CHF
DCM (Outcomes)
once symptomatic:
- exercise intolerance
- syncope
- CHF
- sudden death
DCM (Physical Exam)
- soft left apical systolic murmur
- pulse defecits
- weak pulses (poor cardiac output)
- variable pulses (maybe a-fib)
- tachycardia, tachypnea, soft crackles (L-sided CHF)
DCM (ECG)
- typical sinus rhythm
- L-sided VPCs
- may see a-fib
- patterns of LVH (wide QRS)
- wide p waves possible w/ LA enlargement
T/F; gold standard diagnosis of DCM is echo
T:
you will see reduced fractional shortening, increased heart size, and mitral regurge
DCM (treatment pre-CHF)
- Ace-inhibition if volume overload observed (enalapril)
- pimobendan
- give taurine if nutritionally mediated DCM
DCM (treatment post-CHF)
- O2 when in resp distress
- diuretics (furosemide)
- ace-inhibitors (enalapril)
- pimo
- spironolactone
DCM (prognosis)
roughly 1 year
Canine Arrhythmogenic Right Ventricular Cardiomyopathy
- heat muscle disease with characteristic right ventricular tachyarrhythmias and fibro-fatty infiltration of the RV
- may spread to involve left heart as it progresses
- leads to syncope and sudden death
ARVC (diagnosis)
- holter monitor is the only antemortem gold standard
- -> >300VPCs of RV origin
- -> <100VPCs normal for Boxer
- -> 100-300 meh
Three forms of ARVC
- asymptomatic
- collapse and syncope due to more sever arrhythmias
- structural heart changes may lead to CHF
ARVC (etiology)
- genetic disease of the desmosome
- autosomal dominant pattern of inheritance with incomplete penetrance in the boxer
ARVC (prognostic value of genetic test)
- homozygous positive is the worst
T/F: ARVC with Mutation =/= Disease and Mutation Free =/= Disease Free
T
ARVC (Treatment)
- if symptomatic (syncopal)
- if CHF (treat as DCM)
- Sotalol, Mexiletine
ARVC (prognosis)
- generally good
- bad if positive homozygous for striatin mutation
- bad if structural heart disease observed (type 3)
T/F: most congenital heart diseases are uncommon and are managed medically more often than surgically
T