Feline Cardiomyopathies: Part 1 Flashcards by Rebecca Williamson

T/F: functional (nonpathologic) murmurs are more common in cats

true: 40-60% of cats have murmurs without structural cardiac disease (stress related murmurs!)

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T/F: all cats with CV disease will have abnormalities on cardiac auscultation

false- many will have no abnormalities on cardiac auscultation

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do cats cough secondary to CV disease?

they can, but rarely
dogs often cough from CV disease

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what are the first clinical signs of CV disease in cats?

cats hide clinical signs very well, so often the first clinical sign is when they are in heart failure
- difficulty breathing
- vomiting
- hyporexia
- hiding

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how do cats manifest left sided CHF differently than dogs?

dogs: typically as pulmonary edema only
cats: can manifest as pulmonary edema, pleural effusion, and pericardial effusion because their pleural veins drain differently

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T/F: cats can develop cardiogenic arterial thromboemboli as common as dogs

false- they do develop them but dogs do not develop them for the most part

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T/F: congenital heart disease in cats is not common

true

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T/F: like dogs, cats often get clinically significant acquired degenerative valve disease

FALSE- they do not get clinically significant acquired degenerative valve disease

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feline cardiology general points

congenital heart disease is less common
cats do NOT get clinically significant acquired degenerative heart disease
cats get cardiomyopathies (especially HCM) adult onset
cats get stressed! can precipitate CHF
pilling cats super stressful and challenging

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how are murmurs described in cats?

cranial and caudal and parasternal
as they age, their heart lays pretty flat along sternum

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what are some differential diagnoses for a grade 3/6 caudal parasternal murmur in a cat? (3 broad categories)

congenital heart disease (rare, but this is a young cat): VSD, mitral valve dysplasia
acquired heart disease: cardiomyopathy, etc
functional/physiologic murmur (nonpathologic): common in stressed cats

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T/F: calming/sedation is not helpful to differentiate pathologic and non pathologic murmurs in cats

true- may help murmur go away but cannot prove that is caused by one or the other

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what breeds are predisposed to cardiac disease (cats)

maine coon, ragdoll

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how can you recognize subclinical cardiac disease in asymptomatic cats?

predisposed breed
clinical signs +/-
any additional abnormal heart sounds other than systolic murmur: gallop/arrhythmia/premature beats, etc
if you can feel the murmur: >4 murmur = pathologic murmur

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what species gets summation gallop sounds?

cats

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what are summation gallops?

cats : extra heart sound in diastole
gallops are low-pitched, diastolic heart sounds, abnormal in small animals
often difficult to tell type of gallop because cats hearts are so fast: these are summation gallops (cannot tell if S3 or S4)

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summation gallops are strong indicators of

pathologic heart disease in cats

what is the “classic conundrum” when listening to a murmur in cats

cardiomyopathy (primary vs secondary) vs functional murmur

how can you rule out causes of a functional murmur or secondary CM in cats?

anemia: increases blood flow turbulence
systemic hypertension: comorbid disease: increases afterload which leads to concentric hypertrophy. esp older cats
hyperthyroidism: T4 increases HR and thus turbulent blood flor
Biomarker Nt-proBNP

what are cardiac biomarkers?

natriuretic peptides: ANP vs BNP: species specific
cardiac troponin I: serum: not species specific

what are the natriuretic peptides

ANP, BNP, NT-pro BNP
plasma/pleural efusion
these are neurohormones related to the ventricle that are secreted to help alleviate stretch
they stimulate vasodilation and renal natriuresis: telling the kidneys to make urine and waste Na+
Na+ leaves and water follows, this is decreasing preload
species specific

what is cardiac troponin I- serum

cardiac biomarker in cats
marker of ongoing cardiomyocyte damage/injury, ischemia, cell death, myocarditis, etec
indicator of muscle cell damage/death
not species specific

T/F: the cardiac biomarkers will not tell you what the cause of the cardiomyocyte stress or injury is

true

NT-proBNP in asymptomatic cats?

> 100pnol/L increase likelihood of clinically significant heart disease. need an echo, esp if cat is not azotemic
-<100: can be confident that cat does NOT HAVE significant cardiac disease

NT-proBNP in cats

- quantitative send out: ideal if not in rush (asymptomatic cats) - SNAP plasma test: ideal in symptomatic cats

SNAP NT-proBNP plasma test in cats

- cutoff: > or < 100 pmol/L. less than 100: normal. over 100: abnormal - many false positives in symptomatic cats - normal/negative value MOST HELPFUL in symptomatic cats: helps rule out cardiac disease

what is the idea diagnostic test to determine the cuase of the murmur if you ascultated a grade V/VI right sided parasternal systolic murmur in a 4 month old cat with lethargy and exercise intolerance?

echocardiogram: history tells us that odds are high of true heart disease

what is the most common/important cardiomyopathy in cats?

hypertrophic cardiomyopathy, but cats can get many different types

restrictive cardiomyopathy in cats

fibrosis/scar tissue in heart: can line endocardium or infiltrate myocardium - main pathophysiology: impaired fill = diastolic dysfunction. type 3 collagen is not very compliant and really thick - usually wall thickness normal - uncommon and challenging to diagnose

DCM in cats

- identical pathogenesis in dogs - disease of SYSTOLIC dysfunction - really bad by the time you diagnose it, horrible prognosis - see chamber dilation like in dogs - often idiopathic but rule out taurine deficiency: low taurine can cause DCM in cats

what can be a cause of DCM in cats?

taurine deficiency: necessary for cardia cfunction

ARVC in cats

- somewhat different than dogs : can see obvious dilation/dysfunction in ultrasound of the RV in cats - ascites/right sided CHF= abdominal distension - very rare - usually in heart failure by the time they see us

atrial enlargement ? what is it useful for?

super important prognostic findings on an echocardiogram: the bigger the atria = the worse the heart disease can see bi-atrial enlargement in cat: nonspecific CM

nonspecific CM in cats

- left or bi-atrial enlargement with: - normal wall thickness - seemingly normal systole function - RV not overly dilated - often unable to assess diastolic function

definition of HCM

diffuse or regional/isolated LV wall thickness with nondilated LV chamber (but can be more than LV) walls ABNORMALLY THICKENED main problem: ventricle doesn't fill normally = diastolic function is the issue

echo diagnosis of HCM phenotype

- size of cat's heart is an egg. tiny. diagnose based on wall thickeness measurements: difference of 1 mm is huge - > 6 mm - do end diastolic wall thickness measurements - mild HCM can be hard to diagnose! need to do more - severe hypertrophy easy

HCM phenotype

- echo diagnosis - primary vs secondary HCM = clinical diagnosis

what are causes of secondary HCM?

- systemic hypertension - hyperthyroidism - infiltrative disease (lymphoma, myocarditis) - acromegaly (rare) - aortic stenosis - pseudohypertrophy: ** can be caused by hypovolemia/dehydration! if you have a cat that hasn't drank in a while, will present with an HCM phenotype

what is primary HCM?

literally means you don't know the cause: genetic/idiopathic HCM = diagnosis of exclusion

primary HCM in cats known genetic mutations

Maine Coon: myosin binding protein C3-A31P Ragdoll: myosin binding protein C3-R820W both autosomal dominant with incomplete penetrance

which of the following is a cause of a hypertrophic cardiomyopathy phenotype in cats? a. pulmonary hypertension b. hyperthyroidism c. taurine deficiency d. focal junctional tachycardia

b. hyperthyroidism taurine causes DCM