Feline Heart Disease Flashcards
What aged cats primarily present with congenital and acquired heart disease?
CONGENITAL - younger patients
ACQUIRED - 3 months to 19 years
What are the 5 most common types of primary feline heart diseases?
heart based:
- HCM/HOCM (~58%!)
- restrictive cardiomyopathy - RCM
- DCM
- ARVC
- unclassified cardiomyopathy
What are the 7 most common causes of secondary feline heart disease?
- hyperthyroidism
- acromegaly - increased GH causes the myocardium to thicken
- HW disease
- systemic hypertension
- dietary
- anemia - increased oxygen demand and heart must work harder (remodeling!)
- dehydration (pseudo-hypertrophy)
What are the 2 most common congenital causes of feline heart disease?
- VSD
- valve malformations
DCM vs. HCM vs. RCM:
RCM = muscle replaced by fibrous CT and cannot relax properly to allow for complete filling of the ventricles
What breeds are most commonly affected by HCM? How do they most commonly present?
- Maine Coon
- Ragdoll
- Sphynx
- British Shorthair
- Bengal
- Persian
- several with known genetic mutations, males > females
14-34% are overtly healthy!
What 3 cardiac pathologies are associated with HCM?
- myofiber disarray
- intramural arteriosclerosis
- fibrosis/CT abnormalities
What is the ultimate result in hearts with HCM? What are 3 signs of this?
left ventricular hypertrophy
- systolic murmur at sternum - regurgitation not common, caused by the anterior movement of the mitral valve, which increases the velocity of blood entering the LV
- gallop rhythm
- left/biventricular CHF —> pulmonary edema, pleural effusion
What results from severe cases of HCM? What causes this? What 3 things can this lead to?
diastolic failure —> unable to completely relax to allow for ventricular filling
systolic anterior movement of the mitral valve (HOCM) causes outflow obstruction (thickened septum, and mitral/papillary muscles)
- arterial thromboembolism - enlarged LA and auricle causes turbulent blood flow
- atrial fibrillation
- sudden death
What are the 4 morphological characteristics of primary muscle disease causing HCM?
- ventricular (concentric) hypertrophy
- no dilation
- decreased compliance = diastolic failure
- LV outflow obstruction
What are 3 possible variations of hypertrophy seen in HCM? What does this contribute to?
- diffuse septal thickening
- localized basal thickening
- focal outflow thickening
obstructs aortic outflow
What is the pathophysiology od HCM?
diastolic failure due to concentrically thickened LV —> poor ventricular filling causes poor myocardial oxygenation
+ HR must increase to maintain CO
HCM pathophysiology:
What are 3 signs of HCM on echocardiography?
- higher LA and PV pressures = LA dilation
- smoke in LA due to increased turbulence (thrombus formation!)
- SAM/dynamic outflow obstruction
HCM, LA dilation:
What are the 4 causes of thromboembolism as a result of HCM?
- dilated LA and left auricular appendage = turbulent flow
- endocardial injury
- stasis in LAA
- hypercoagulability
(saddle thrombus if it leaves the left side of the heart!!)
What are clinical signs of thromboembolism in cats with HCM?
- extreme pain
- paralysis/paresis
- respiratory distress from pain and CHF
- no femoral pulse
- hypothermia
- purple and cold pads/nails
- gastrocnemius spasm
- anorexia, vomiting
- hyperkalemia, increased CK and NT-proBNP
What is the most common cause of heart murmurs heard in cats with HCM?
systolic anterior motion of the mitral valve (SAM)
- septal mitral valve leaflet or chordal structures are pulled into LV outflow tract during systole
- leaflet is caught in flow, producing a dynamic subaortic stenosis that increases the velocity of blood
- when the leaflet is pulled toward the interventricular septum, a gap in the mitral valve is produced = mitral regurgittion
HCM, echo:
- large LA
- mitral valve pulled toward septum
What is the clinical significance of SAM?
- can cause intermittent murmurs - mitral regurgitation and LA dilation
- may affect therapeutic recommendations
- causes aubaortic stenosis
- initiates/progresses hypertrophy
- possibly higher risk for sudden death or progression to clinical signs
How do most cats auscultate with HCM?
- 50% have murmurs +/- gallop S3
- crackles/edema with edema, may have quiet lungs with high RR and effort
How is respiratory effort affected by HCM?
> 30 bpm at rest at home and >36 bpm in exam room —> respiratory distress due to pleural effusion/edema
HCM, ECG:
- VPCs
- ventricular tachycardia
- increased R wave amplitude
How does HCM appear on radiographs?
DV —> Valentine heart due to LA dilation and cardiomegaly
HCM, radiographs:
enlarged LA and pulmonary veins
HCM, radiographs:
pleural effusion progression following a tap
How is HCM definitively diagnosed?
echocardiograph —> thick left ventricle, loss of normal “mushroom sign”
HCM, echo:
heart suspended in pleural fluid
HCM, echo:
LA enlargemennt
- should be close to the size of the aorta
HCM thrombus, echo:
smoke in LA!
What does the normal size of the heart in cats depend on?
expected values based on weight
How do NT-proBNP tests compare for diagnosing HCM?
- in-house/point of care SNAP = way to rule out distress caused by cardiac vs respiratory, cats showing clinical signs!
- send out = screening, determines risk
What are the 5 stages of HCM?
- A = normal echo, predisposed breed
- B1 = subclinical, low risk
- B2 = subclinical, higher risk
- C = clinical with current/previous CHF or ATE
- D = clinical with refractory CHF
How are owners educated about stage A HCM? Is treatment indicated?
cat is seemingly healthy, but will need some form of yearly follow-up
NO
WHat are some diagnostics used to screen cats in Stage A HCM?
- auscultation
- RR at rest and at home
- chest rfads
- echo
- NT-proBNP
What is stage B1 HCM? What is required for diagnosis? What screening is recommended?
evidence of LV hypertrophy, but no significant LA enlargement —> subclinical, low-risk
ECHO
screen annually with auscultation, RR at rest at home, chest rads, echo, and NT-proBNP —> no treatment needed
What is stage B2 HCM? Is treatment recommended? What if there is HOCM?
moderate to severe LV hypertrophy with LA enlargement —> subclinical, high risk for developing failure, ATE, or SAM
YES —> Clopidogrel (+/- Aspirin) and arrhytmia treatments
Atenolol —> still has good systolic function, can increase CO and afterload to decrease SAM
What new drug may be available for better treatment of stage B2 and above HCM?
Rapamycin —> may be able to reverse hypertrophy
What monitoring is recommended for stage B2 HCM?
- RR at rest as home
- minimize stress from exams with medication
- monitor for development of CHF and ATE
- q 6-12 months - chest rads, ECG, echo, NT-proBNP
What 4 effects do beta-blockers have in the treatment of HOCM?
- decreases LV outflow tract obstruction
- decreases HR to improve filling
- decreases wall tress and myocardial oxygen demand
- anti-arrhythmic
What is stage C HCM? How do patients present?
moderate to severe LA enlargement and LVH, but patients are now clinical and at HIGH RISK for developing ATE and recurrent CHF
- lethargy, hyporexia/anorexia
- tachypnea, dyspnea
- syncope
- paralysis/paresis
- hypothermia
- murmur
What 7 aspects of stage C HCM are treatable? How?
- DECREASE PRELOAD - diuretics to resolve edema/effusion
- INCREASE INOTROPY - Pimobendan
- DECREASE AFTERLOAD - Benazepril, Spironolactone
- OPTIMIZE HR - control arrhythmias
- BLUNT RAAS - Benazepril, Spironolactone
- THROMBOSIS - Clopidogrel +/- Aspirin, factor Xa inhibitor, LMWH
- ANXIETY - Gabapentin, Buprenorphine
(no evidence that any therapy beyond diuretics imrpove survival)
What 7 treatments/diagnostics are recommended in cats with acute CHF with HCM? What is avoided?
- OXYGEN
- anxiolytic
- tap chest
- FUROSEMIDE IV
- baseline bloods (PCV/TS, renal values, Na, K, BUN, CREA)
- Pimobendan
- Clopidogrel (consider Rivaroxaban with LA dilation or present clot)
FLUIDS
Cat, CHF:
- pulmonary edema
- pleural effusion
Cat, CHF:
pleural effusion
What should be monitored in cats with acute CHF and HCM? What is the goal?
- temp
- RR
- BW
- BP
- urine output
- renal values and electrolytes
get stabilizes and home ASAP —> return in 3-7 days for re-evaluation (log at home resting RR and ensure its consistently <30 BPM at rest) + recheck q 2-4 months
What 3 medications are recommended to go home after acute cases of CHF from HCM? What is added once cat is stabilized?
- Furosemide
- Pimobendan
- Clopidogrel
Benazepril + Spironolactone
What 5 treatments are recommended in cats with stage C HCM? What monitoring is recommended?
- Furosemide - taper to lowest dose possible to maintain RR < 30
- Pimobendan
- Clopidogrel
- low salt diet
- Benazepril and Spironolactone once renal values are normalized
rechecks q 2-4 months - renal values, electrolytes, RR and effort, weight
What is stage D HCM? What 5btreatments are recommended?
refractory CHF in cats with HCM
- Furosemide - taper to lowest dose possible to maintain RR < 30
- Pimobendan - increase to TID and higher doses
- Clopidogrel
- low salt diet
- Benazepril and Spironolactone once renal values are normalized
What monitoring is recommended for stage D HCM?
rechecks q 2-4 months - renal values, electrolytes, RR and effort, weight
When is thromboembolytic treatment in cases of HCM contraindicated?
- early stages A and B1
- ATE has already developed
What 2 cardiac changes do restrictive cardiomyopathy result in? What does this cause?
- diffuse LV endocardial fibrosis (scarring)
- myocardial fibrosis
normal sized LV, larger LA +/- RA = diastolic dysfunction
What are 3 causes of restrictive cardiomyopathy?
- amyloidosis
- storage disease
- inflammatory disease with severe reparative fibrosis
What are 5 signs of restrictive cardiomyopathy?
- systolic or gallop rhythm
- left/biventricular CHF
- ventricular arrhythmias
- ATE
- sudden death
RCM, echo:
- biatrial enlargement
- normal LV wall thickness
Why is feline DCM much less common now?
cat foods supplement the necessary levels of taurine
What is the normal morphological characteristics of feline DCM? What does this cause?
dilation of 2 or 4 chambers —> ventricles/left side > atria/right side —> eccentricl hypertrophy
systolic dysfunction of one or both ventricles (poor fractional shortening)
What breeds are predisposed to developing feline DCM? What are the primary causes of resulting systolic dysfunction?
Burmese, Siamese, Abyssinian
- chronic volume overload
- ischemic heart disease
- myocarditis
What 2 laboratory tests should be performed in cases of cats with systolic dysfunction?
- whole blood taurine levels
- troponin I - detects ischemic myocardial disease nad myocarditis
DCM, echo:
- eccentric hypertrophy
- increased end-diastolic LV diameter and end-systolic LV diameter = poor fractional shortening
What are the 4 morphologic characteristics of feline arrhythmogenic right ventricular cardiomyopathy (ARVC)?
- RA and RV dilation
- RV systolic dysfunction
- normal to mildly reduced LV systolic function
- arrhythmias - ventricular > supraventricular
What gross changes are seen in the heart with feline ARVC?
severe loss of RA and RV muscle, causing thinning and dilation of the walls
Echo HCM vs. DCM vs. HOCM vs. RCM:
- HCM = small lumen, concentric hypertrophy
- DCM = large lumen, eccentric hypertrophy, poor contractility
- HOCM = thickened septum or valve leaflets blocks aortic outflow
- RCM = enlarged RA and LA, normal ventricles
HCM/HOCM vs. DCM vs. RCM vs. ARVC:
What history is especially important to get in cats with heart failure?
FULL dietary history
- taurine deficiency associated with “boutique” or grain-free diets
- peas, lentils
- toxins
- tell owners to only purchase WSAVA approved diets
