Acquired cardiovascular disease in cats Flashcards
Primary cardiomyopathies
hypertrophic (HCM) dilated (DCM) restrictive (RCM) arrythmogenic RV (ARVC) unclassified (FUCM)
hypertrophic cardiomyopathy (HCM)
idiopathic left ventricular hypertrophy
most common feline myocardial disease
HCM - pathophysiology
impaired ventricular relaxation - incr atrial pressures
incr ventricular stiffness - congestive failure
dynamic left ventricular outflow tract obstruction - abnormal movement of anterior mitral leaflet in systole
HCM - pathological findings
LV hypertrophy affects septum + free wall
LA may be dilatedwhen filling pressures incr
myocardial infarction may occur - appears as localized wall thinning + scarring
HCM - signalment
most common in young adult males
most cats with HCM are moggies
HCM - clinical signs
asymptomatic mostly
congestive heart failure
aortic thromboembolism - worst
sudden death
HCM - physical exam
\+/- variable intensity systolic murmur prominent apical impulse ± gallop sounds ± tachpnoea, crackles physical exam may be completely normal
HCM - radiography
LV hypertrophy → ‘long’ cardiac silhouette on the lateral
pulmonary oedema and/or pleural effusion usually indicates congestive heart failure
HCM - echocardiography
LV hypertrophy - diastolic septal or free wall thickness ≥6mm (focal or generalised)
Systolic anterior motion (SAM) of the mitral valve causes DLVOTO and a murmur
HCM - prognosis
poor if clinical signs, LA enlargement, ATE
Dilated cardiomyopathy (DCM)
dilation of all 4 chambers
thinning of ventricular walls + hypokinesis
taurine deficiency
uncommon
DCM - clinical signs
Middle-aged and older cats
Taurine-deficiency DCM in cats fed on dog food.
output failure - Hypotension, Hypothermia, Bradycardia
Murmur quiet/ absent - gallop may be present
Thromboembolic disease is common.
DCM - echocardiography
Dilated, spherical LV
fractional shortening < 30%,
LV end-systolic diameter >12mm
DCM - prognosis
grave
restrictive cardiomyopathy (RCM)
Severely impaired diastolic filling Stiff LV relatively normal left ventricular dimensions + systolic function. Endomyocardial +Myocardial form Severe atrial enlargement in both forms
RCM - clinical signs
Older cats Dyspnoea from pleural effusion common ± low output signs ± aortic thromboembolism Arrhythmias common
RCM - echocardiography
Severe biatrial enlargement
Endomyocardial form of RCM is distinctive - endomyocardial scarring is readily imaged
Myocardial form is more challenging- LV may appear relatively normal
Arrhythmogenic right ventricular cardiomyopathy (ARVC)
fibrofatty infiltration of right ventricle
right heart enlargement
May be asymptomatic
May be syncopal in association with arrhythmias
May have right-sided heart failure
ARVC - echocardiography
Severe right ventricular and right atrial dilation
Tricuspid regurgitation usually present.
cats at risk of HCM
Maine coons, Ragdolls etc may be at incr genetic risk of HCM, but MBPC mutation testing only valid for maine coons
ANY cat could be at risk of HCM
Echocardiography provides definitive diagnosis
Can consider NT-proBNP as initial step?
asymptomatic cats (HCM) - treatment
some affected cats at low risk + need no treatments
ACE inhibitors - consider if LA dilated?
Diltiazem - licensed, but no good evidence of benefit
Beta-blocker (atenolol) good for control of LVOTO- but is there long term benefit?
Acute, life-threatening heart failure - treament
Echo less stressful than radiographs, and if LA dilation is identified, can support aggressive management of congestive failure
administer O2 - oxygen cages
Sedation - more important to sedate cats than dogs, as dyspnoeic cats often become very distressed (butorphanol)
IV furosemide to effect - to decr resp rate
Thoracocentesis: Significant pleural effusions are more common than in dogs with congestive heart failure - should be drained while causing minimal stress
Increase cardiac output? -Difficult, If BP normal, just treat congestive signs, avoid IV fluids (Will not increase output, & will worsen CHF)
mild-moderate heart failure - treatment
can usually be treated as out-patients eliminate abnormal fluid retention modulate neurohormonal activation optimize haemodynamic function prevention of thromboembolism
eliminate fluid retention - drugs
Furosemide - use to effect
ACE inhibitor - benazepril
