Feline Myocardial disease Flashcards
What are primary feline myocardial diseases?
- Hypertrophic cardiomyopathy (HCM)
-With or without LV obstruction - Restrictive cardiomyopathy (RCM)
- Non-specific cardiomyopathy (NS-CM)
- Dilated cardiomyopathy (DCM)
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
What are secondary feline myocardial diseases?
- Hypertensive cardiomyopathy
- Hyperthyroid cardiomyopathy
- Cardiomyopathy associated with:
-acromegaly
-azotaemia
-diabetes mellitus etc. - Transient myocardial thickening
-Young cats, follows stressful incident.
-Reversible cardiomyopathy
What can feline systemic hypertension lead to?
Secondary cardiomyopathy
What should be ruled out that may cause concentric hypertrophy before diagnosing feline hypertrophic cardiomyopathy?
Aortic stenosis
Systemic hypertension
Hyperthyroidism
Chronic renal failure
Acromegaly (+/- diabetes mellitus)
Transient myocardial thickening
What’s the most common cause of a heart murmur in cats?
- Hypertrophic cardiomyopathy
What is HCM in cats?
- familial disease reported in Persians, Ragdolls, Maine coons, Sphinxes, American shorthairs, British shorthairs, Norwegian Forest cats, etc.
- Autosomal dominant trait
- Maine coons & Ragdolls; mutations detected in genes encoding Myosin binding protein C, Sphinx: ALMS1 gene (genetic tests available)
How do cats present with preclinical HCM?
What biomarkers are increased?
- asymptomatic heart murmur
- Sometimes arrhythmias, diastolic gallops on physical exam
- increased NT-pro-BNP +/or Troponin I (cardiac biomarkers)
How do cats present with clinical HCM?
- Dyspnoea or tachypnoea because of congestive heart failure (pulmonary oedema and / or pleural effusion
- Feline arterial thrombo-embolism (FATE)
- Syncope / odd episodes
- Periods of open-mouth panting
- Sudden death
What is seen with Feline arterial thromboembolism
- V painful
- more painful than RTAs
- Loss of hindlegs - external iliacs usually embolised (saddle thrombus)
How do you classify feline HCM?
- A = predisposed
- B1 = subclinical - normal/mild atrial enlargement
- B2 = subclinical - moderate/severe atrial enlargement
- C = current / previous CHF / Arterial thromboembolism
- D = Refractory CHF
What are heart sounds?
- S1 = closure of AV valve
- S2 = Closure of semilunar valves
abnormal - S3 = rapid deceleration of blood in LV
- S4 = LV filling associated with atrial contraction
How would you treat a cat with heart failiure? (HCM)
- Diuretics - furosemide
- Venodilators - GTN (if life-threatening pulmonary oedema
- ACE inhibitor (not licenced - but Benazepril is)
- Angiotensin II receptor blocker - Telmisartan
- Clopidogrel = prevent thromboembolism
What could you do with asymptomatic cats?
- Beta blocker / Ca channel blockers
- no strong evidence of improvement
- DONT give beta blocker if CHF
If dilated cardiomyopathy, what must be excluded in cats? Tx?
- Taurine deficiency
- Tx = pimobendan (+ve inotrope), warmth, humidified o2, drain effusions, furosemide
What are the 2 forms of restrictive cardiomyopathy? What are they characterised by?
- Two forms:
- Myocardial form
- Endomyocardial form
- Characterised by:
– Relatively normal LV wall measurements
– Relatively normal LV chamber dimensions
– Relatively normal LV systolic function
– Usually marked LA enlargement
– Diastolic function: restrictive physiology
What is non-specific cardiomyopathy?
- Features of more than one form of cardiomyopathy
- e.g. Systolic dysfunction with abnormal LV filling
- Describe the abnormalities
– This example: 4 chamber dilatation, impaired LV systolic function, “smoke” in LA, small pericardial effusion (due to CHF)
What is arrhythmogenic RV cardiomyopathy?
- Fatty replacement of myocardium, initially around RVOT.
- Usually marked dilatation of the right heart.
- May show ventricular arrhythmias or conduction disturbances but most commonly, affected cats present with R-CHF (e.g. ascites).
- Some cats have 3rd degree AV block
What should be done to cats with dyspnoea due to life threatening pulmonary oedema?
- DO NOT STRESS!
- Provide oxygen, without additional stress (oxygen cage in quiet, dark room)
- Administer furosemide (IV if an IV catheter can be placed without stress; otherwise IM)
- Nitroglycerine topically (Percutol) (if available)
- Sedation if cat very anxious (opiates e.g. methadone).
- Only after the cat is stabilised should you undertake diagnostic tests
What should be done to dyspnoeic cats with CHF?
- Oxygen therapy (humidified)
- Reduce anxiety (e.g. butorphanol)
- Calm, gentle handling & environment
- Delay investigations until more stable.
- IV Furosemide
- Drain pleural effusions
How can you screen cats for HCM?
- Annual Echo - pedigrees
- NT-pro-BNP SNAP test for clinical cases
