Acquired Heart Diseases Flashcards
what is MMVD
degeneration and thickening of the mitral valve leading to incompetency (regurgitation), left atrial enlargement, volume overload, and CHF
is pulmonary venous hypertension the same as pulmonary hypertension (arterial)
NO - venous hypertension should resolve when L-CHF is treated
can become clinically significant and require treatment
what factor determines if MMVD patients require treatment
LA enlargement
what are common outcomes of MMVD
- L-CHF (possibly biventricular)
- pulmonary hypertension
- LA rupture
- atrial fibrillation
pimobendan
inodilator - positive inotrope + peripheral vasodilation
increases inotropy by increasing Ca sensitivity in cardiomyocytes NOT increasing overall amount of Ca
enalapril/benazepril
ACE inhibitors
inhibits RAAS activation to slow volume overload to the left heart
furosemide
diuretic
promotes excretion of excess fluid volume (pulmonary edema)
spironolactone
aldosterone inhibitor
inhibits RAAS activation to slow volume overload
sildenafil
PDE inhibitor
dilates pulmonary vasculature to reduce pulmonary hypertension
RARELY used for MMVD - venous hypertension often resolves with CHF management
risky bc dilation of pulmonary vessels will increase volume to L heart
MMVD prognosis
~15 mo from stage B2 to development of CHF
~12 months after onset of CHF
what is dilated cardiomyopathy
heart muscle disease with characteristic ventricular dilation leading to systolic dysfunction
primarily affects the LV
pathology of DCM
severe dilation of LV + LA +/- RV
myofiber degeneration and necrosis with minimal to no inflammation
is the mitral valve abnormal in DCM
NO - normal mitral valve at the start of disease, stretch from LV dilation causes regurgitation
how is the occult phase of DCM diagnosed
occult phase is often long and difficult to diagnose
requires Holter monitoring, NT-proBNP, C-TNI, or PDK4 genetic testing
outcomes of DCM
- exercise intolerance
- syncope
- L-CHF (cough, resp effort)
- sudden death
is the murmur from MMVD or DCM louder
MMVD
DCM is quieter because it is not a primary mitral valve problem
prognosis of DCM
occult: months to years with pimobendan
DCM w/ CHF: 9-12 months with treatment
what is canine ARVC
heart muscle disease with characteristic right ventricular tachyarrhythmias + fibro-fatty infiltration of the right ventricle (+ left if progressed)
leads to syncope and death
what does incomplete penetrance of the mutation mean
not all boxers with the mutation are affected with clinical ARVC
what does variable expressivity of the mutation mean
boxers with the mutation are affected with variable severity
homozygous: earlier onset, accelerated disease course, increased risk of sudden death
outcomes of ARVC
- RV arrhythmias
- collapse or syncope
- sudden death
what are the three forms of ARVC
- asymptomatic
- collapse and syncope
- structural changes
asymptomatic ARVC
no clinical signs but meets diagnostic criteria on holter monitor
collapse/syncope ARVC
clinical signs + meets diagnostic criteria on holter monitor
structural changes of ARVC
DCM-like changes on echocardiogram (LV, LA dilation)
if NOT a boxer - structural changes occur on the R side
sotalol
beta blocker
anti-arrhythmic drug - prevents ventricular arrhythmias
mexiletine
anti-arrhythmic often prescribed alongside sotalol alone
prognosis for ARVC
good if heterozygous
poor if homozygous or type III disease
cause of death is usually sudden death
what is hypertrophic cardiomyopathy
heart muscle disease with characteristic left ventricular wall thickening leading to diastolic dysfunction
what is HOCM
hypertrophic obstructive cardiomyopathy
subset of HCM that progresses to the point where the thick ventricle wall blocks the left ventricular outflow tract
what are other cardiomyopathies in cats
- RCM (restrictive): diastolic dysfunction despite normal wall thickness
- UCM (unclassified/non-specific)
- DCM - associated with taurine deficiency
what are acquired heart diseases in cats
secondary changes to the heart in response to systemic disease
- systemic hypertension
- hyperthyroid associated CM
- endocarditis
**mmvd is NOT in cats, endocarditis is RARE
what diagnostics should always be performed in cats found to have LV hypertrophy
blood pressure
free T4
are heart murmurs a reliable indicator of heart disease in cats
NO
- 50% of cats with murmurs do NOT have cardiac disease
- 50% of cats wit1h heart disease do NOT have murmurs
can be prioritized in older cats
are gallop sounds reliable indicators of heart disease in cats
yes - highly sensitive
always investigate if S4 gallop is heard
when are thoracic radiographs beneficial to use in suspect heart disease cats
symptomatic cats
can ID cardiomegaly (specific for heart failure)
can NOT see concentric hypertrophy on radiographs
at what value is a quantitative NT ProBNP test positive for heart disease
> 99
good for disease detection in occult stage cats
at what value is a SNAP NT-ProBNP test positive for heart disease
> 200
good for differentiating cardiac disease from respiratory disease in emergency settings
is ECG beneficial for diagnosing occult HCM
specific but not sensitive
only indicated if cat has arrhythmias or pulse deficits
- abnormal complexes are highly specific for heart disease
what ventricular or IVS wall thickness is diagnostic for HCM
> 6 mm
clopidogrel
platelet inhibitor
used in EVERY cat with HCM due to high risk of arterial thromboembolism from LA dilation
atenolol
beta blocker
used for SYMPTOMATIC (collapse) but NOT YET CHF cats
- most commonly HOCM w/ severe outflow tract obstructions
do NOT use with evidence of chamber enlargement
5 functions of atenolol
- anti arrhythmic
- negative inotropy - decreases myocardial O2 demand
- negative chronotrophy - decreases HR to increase time in diastole
- negative lusitropy - relaxes the heart
- antifibrotic
why can HCM in cats present similarly to respiratory disease
HCM can progress to L-CHF –> in cats, can cause pleural and pericardial effusion
thoracic radiograph findings in cats w/ HCM + CHF
- cardiomegaly
- pulmonary edema
- pleural effusion
always tap the chest and treat with furosemide before and after radiographs
b lines
interstitial lung disease - indicative of pulmonary edema
does pericardial effusion associated with CHF need to be tapped
no - will resolve with HCM and CHF treatment
management of acute respiratory distress in cats
- sedate - butorphanol
- O2 supplementation
- furosemide
- albuterol
- diagnostics - thoracocentesis, thoracic radiographs, echo
- at home management once stabilized
treatment for HCM w/ CHF
- furosemide
- ACE inhibitors
- clopidogrel
- pimobendan
- STOP use of B-blockers
