Acquired CV Disease Cats Flashcards
What is the cause of the majority of acquired cardiac disease in cats?
Cardiomyopathy (can be complex cardiopathy)
- congenital and primary arrythmias also possible but less common
- 1* valvular disease VERY RARE
- pericardial disease much less common than dogs
What are the 4 main types of cardiomyopathy?
> hypertrophic (HCM)
dilated (DCM)
restrictive (RCM)
arrythmogenic RV (AVRC)
Potential 2* myocardial diseases in cats?
- hyperthyroid myocardial disease
- hypertensive myocardial disease
- cardiomyopathy 2* to hypersomatotropism (acromegaly)
What are the key features of HCM?
- concentric Lv hypertrophy (diastolic septum/free wall thickness >6mm)
- poor LV relaxation (stiff)
- primary diastolic dysfunction
- later stages see poor systolic function due to LV scarring
- myocyte dissaray
> narrowed coronary aa. can lead to myocardial infarction
What are the key features of RCM?
- much less common than HCM and DCM
- marked atrial dilation
- no LV hypertrophy or dilation
- stiff LV
- myocyte dissarray
What are the key features of ARVC?
- left heart normal
- severe dilation of RA, RV
- RV wall thinning
- fibrofatty replacement
What does SAM describe? What predisposes this?
- systolic anterior motion
- mitral valve leaflets flap over and cause LVOTO
> valve leaflets may be especially long
> worse with septal hypertrophy
> worse with ^ sympathetic tone
> seen with HCM
What is the cause of HCM?
> Idiopathic or genetic
- NOT 2* to hypertension, aortic stenosis or hyperthyroidism
What is seen in advanced HCM?
- left atrial dilation
- left artrial contractile dysfucntion (-> thrombus formation)
- left ventricular systolic dysfunction (-> ^ atrial pressure)
What occours with HCM?
Dynamic left ventricular outflow tract obstruction (SAM)
- causes mitral regurgitation
Which cats are most commonly seen with HCM?
- young adult males but can be seen in all ages
- maine coons, ragdolls, persians predisposed BUT majority non-pedigree
Presenting signs for HCM?
- asymptomatic
- respiratory distress (suggests heart failure)
- hind limb paralysis due to aortic thromboembolism
- sudden death
PE findings with HCM?
- +- variable intensity murmur (may be present when young but disappear when older due to LV necrosis and fibrosis replacing the hyerptrophied muscle)
-priminant apical pulse - +- gallop sounds
- +- tachypneoa and crackles
> physical exam MAY be completely NORMAL
What concurrent clinical signs make prgonsis of HCM worse?
Arrythmia
What may be seen on radiograph with HCM?
> LV hypertrophy -> long cardiac sillhouette on lateral
> pulmonary oedema or plerual effusion (CHF)
What is the one main indicator of prognosis in cats with myocardial disease?
LA enlargement
What is seen on echo with HCM?
- LV enlargement, diastolic wall thickness >6mm
- SAM causing DLVOTO and murmur
Prognosis for HCM?
- good short term if LA normal
- poor if clinical singns, LA enlargement and ATE (aortic thromboembolism)
What is DCM characterised by?
- dilation of all 4 chambers
- thinning of ventricular walls
- hypokinesis (systolic dysfunction)
What was DCM historically associated with? Is this a common problem now?
taurine deficiency - rarely seen now, most diagnosed cats have normal taurine
Clinical presentatino of DCM
- middle aged/old cats
- taurine-deficient cats if fed on dog food
- output (forward) failure (hypotension, hypothermia, BRADYCARDIA cf. dogs tachycardia)
- murmur quiet/absent but gallop may be present
- thromboembolic disease common
Echo findings with DCM?
- dilated SPHERICAL LV
- fractional shortening 14mm
Prognosis for DCM?
Grave
What are the 2 forms of restrictive cardiomyopathy?
- endomyocardial (severe endomyocardial scarring, bridging scars etc.) seen commonly in oriental breeds
- myocardial (normal LV dimensions)
> both forms have severe atrial enlargement
clinical presentation of RCM
- older cats
- dyspnoea and pleural effusion
+- low output signs (forward failure)
+- ATE - arrythmias common
echo findings of RCM?
- severe biatrial enlargement
- endomyocardial form is distinctive (scarring seen)
- myocardial form more challenging, LV may appear normal
What constititues RCM?
- severely imparied diastolic fillin
- still LV
- relatively normal left ventricular dimensions and systolic function
prognosis for RCM?
poor
What is arrythmogenic right ventricular cardiomyopathy (ARVC) characterised by?
- fibrofatty infiltration of RV
- marked right heart enlargement
- may be asymptomatic
- may be syncopal in association with arrythmias
- may have RCHF: ascites etc. (rare in cats)
echo findings with ARVC?
- severe right ventricular and right atrial dilation
- tricuspid regurgitation usually
What is Tx of feline heart disease based upon?
Stage of disease more than type of cardiomyopathy
What are the stages of cardiac disease in cats?
A: predisposed (all cats!) B1: Preclinical: HCM, no CHF, normal LA B2: HCM, no CHF, big LA C: HCM + CHF (past or present) D: HCM + CHF refractory to Tx
Which cats has a genetic screening test for HCM been developed for?
Maine coons and ragdolls
What is the first step in deciding severity of cardiac disease? How may a definitive diagnosis be made?
NT pro-BNP
Which cats is tx of heart disease NOT indicated for?
> asymptomatic B1 grade with low risk of complications
- no gallop
- no arrythmia
- normal LA size
- low BNP/ANP
What drug may be indicated for cats with LVOTO?
Atenolol (B blocker)
- no evidence for ^ survival
- but in humans chest pain reported so may help with this
- trial and then stop if no improvement reported
Which cats is prophylactic Tx indicated for? What tx?
> Asymptomatic B2 grade High risk cats - LA dilation - systolic dysfunction - extreme hypertrophy > Anti-thrombotic to v risk of ATE eg. Clopidogrel or aspirin (clopidogrel better but tastes gross)
How should C grade HCM be diagnosed?
- suspect CHF from clinical exam
- Echo less stressful than radiographs
- LA dilation identified then start aggressive management of congestive failure
Can any drugs reduce the risk of heart failure?
No
How can acute, life threatening congestive failure be treated?
> improve oxygenation
- administer O2
- sedation (dyspnoeic cats get v stressed) Butorphanol
- IV furosemide to effect (initial dose lower than dogs)
- thoracocentesis (significant pleural effusion more common than in dogs)
- ^ CO (difficult! if BP normal just treat congestion, DO NOT USE FLUIDS! Will ^ congestion and not ^ CO)
What are the aims of home therapy for mild-moderate heart failure?
> mild-moderate no need to be hospitalised
- eliminate abnormal fluid retention (furosemide, benazepril ACEI)
- modulate neurohormonal activation (benaxepril/imidapril ACEI)
- optimise haemodynamic function (pimobendan for systolic function)
- prevent thromboembolism (aspirin or clopidigrel)
How was diastolic heart fialure treated in the past? How has this changed?
HR slowed and negative inortrope using atenolol (B blocker)
- no longer indicated as caused death faster
Which drugs can be aded if cats become refractory to furosemide and ACEI?
> Spironolactone (not licensed in cats, dose similar to dogs. Skin reaction reported)
Thiazides
Pimobendan for systolic dysfunction (NOT FOR DLVOTO)
When is ATE risk high?
Poor contractility and dilation of LA
Management of acute ATE?
- analgesia (methadone, fentanyl CRI)
- manage electrolyte/acid base abnomalities
- prevent thrombus extension (early use clopidogrel)
- pulses return withing 72hrs, use of limbs may take longer - physio needed
x thrombolysis usually associated with ^ risk of reperfusion syndrome so NOT attempted
How may systemic thromboembolism be prevented?
- Clopidogrel
- Aspirin (less effective)
x warfarin not recomedned
x low molecular weight heparins not recommended
