Feline cardiomyopathies Flashcards
How are CMO’s in cats classified?
By their morphological appearance
Hypertrophic, dilated, restrictive
What is the most common type of CMO in cats?
Hypertrophic (HCM)
What is the aetiology of feline HCM?
Idiopathic
Strong genetic presiposition in some breeds
Parvovirus maybe has some roll?
What 4 cat breeds have a strong genetic predisposition for developing Hypertophic CMO? (HCM)
Maine Coon
Persian
Ragdoll
American Shorthair
Describe the pathophysiology of HCM?
(Hypertrophic CMO) Thickening of LV wall and septum Lumen becoming smaller Stiff ventricular walls Diastolic dysfunction - muscles don't relax properly so it can't fill Poor LV filling Low stroke volume Neurohormonal activation Tachycardia Worsening LV filling Increased LV filling pressures Enlarged left atrium \+/- pulmonary congestion, thrombus formation in Left side, arterial thromboembolism
Why are you less likely to see atrial fibrillation in cats compared to dogs?
Cats are smaller and therefore have less cells
Less cells the electro-message need to pass through to get the muscle fibers to all get ready to contract at the exact same time
(Less parts=less chance of fuck up)
What are the 5 pathophysiological complications of feline hypertrophic CMO?
Left ventricular outflow tract obstruction (from increased muscularity)
Myocardial ischaemia
Mitral insufficiency
Atrial fibrillation (uncommon)
Biventricular failure with pleural effusion
What are some clinical features of a cat with HCM?
Signalment - middle-aged, more commonly male
May be asymptomatic for years
Maybe a murmur - systolic, usually mitral
+/- gallop sound
+/- arrhythmia
Usually good pulses and strong apex beat (precordial impulse)
Mostly present with respiratory signs or aortic thromboembolism
Tachypnoea, panting with mild exertion, dyspnoea
Maybe muffled lung sounds - pleural effusion
Coughing is Uncommon!
What are some clinical features of a cat with an aortic ‘saddle’ thromboembolism?
Very painful for a while (hour or so) and then no feeling in hind limbs
Cold back limbs
Cyanotic foot pad
Muscles are ischaemic - go into rigor
Although feline HCM develops over time, why do many present acutely?
Cats are very sensible about exercise and can hide the development of pathological changes
Therefore may present with acute development of CHF or sudden death
How do you diagnose a cat with a suspected HCM?
Compatible history and physical exam
Echocardiography is the best way to distinguish*
Radiograph for a ‘valentine’ shaped heart - changes not always present
ECG most will have changes
Always rule out secondary causes
List 4 secondary causes of HCM that you need to rule out when diagnosing?
Hyperthyroidism (common in cats)
Systemic hypertension
SAS
Taurine deficiency
What are the 4 principle aims of treating asymptomatic HCM?
Prevent CHF from developing
Prevent arterial thromboembolism
Prevent sudden death
Prevent or reverse myocardial abnormalities
What makes treatment of feline HCM so difficult?
Very hard to diagnose in the first place
-Don’t treat a murmur empirically
How do you treat a cat with asymptomatic HCM?
Anti-thrombotic therapy
Beta blocker
Calcium channel antagonist - diltiazem (but can get anorexia, weight loss, skin lesions)
ACEI
-Treatment in asymptomatic phase theoretically makes more sense in this disease