Feline Cardiomyopathy

HCM

Pathoengesis

•Dysfunctional sarcomere

•Poor contractility

•Disorderly arrangement of myofibrils

•Thickening and fibrosis of myocardium

•Poor myocardial perfusion

•Poor contraction

HCM how are myofirbils involved?

Erratically formed myofibrils then ventricular wall becomes prog more thick → chamber gets smaller and smaller and chamber can’t fill up with enough blood → poor output

Which is abnormal, why?

Left
Lv wall thickened
Interventricular septum is enlarged

HCM signalment

All cats can get it
Predipsoed in purebreds, bristish shorthairs, Maine Coon, Norwegian Forest, Sphinx

HCM CX

•Asymptomatic (murmur on auscultation)

•CHF usually of the left heart (cardiogenic oedema occurs)

•Acute “paralysis” saddle embolus

•Dyspnoea

•Cats don’t typically have exercise intolerance

Murmur in HCM

2 causes?

•Mitral leak due to disruption of annulus

•Systolic anterior motion of mitral valve (SAM)

hcm

How does mitral disruption occur?

Thickened LV wall disrupts shape of the mitral valve annulus causing leaking

Staging of HCM

A - Predisposed

B1 (low risk of ATE) - SC (Normal/mild atrial enlargement)
B2 (higher risk of ATE) - SC (Moderate/severe atrial enlargement)

C - Current/previous CHF/ATE

D - Refractory CHF (dying from heart failure)

What can cause a hypertrophic heart?

•HCM

•Pressure overload - measure BP (systemic vascular resistance)

•Systemic hypertension

Confirming DX of HCM?

•Rads – size of cardiac silhouette (can’t se wall thickness

•ECG – doesn’t give accurate prediction of chamber size

•ECHO - - measure wall thickness, assess contractility  (Gold standard)

• LV free wall should be >5.5mm to be diagnostic

What can we see in B and C?

B - focal area of thickening

C - Thickened walls (white) with black triangle showing small chamber

Other tests for HCM that involve concurrent diseases

CBC – polycythemia? (chronic hypoxia)

–Concurrent diseases?

Serum biochemistry

–Chronic kidney disease – hypertension

–Diabetes? Hypertension

–Electrolyte imbalances – endocrine diseases?

T4 – common cause of hypertension in older cats

•Unkempt coat?

•Weight loss?

•Retinal haemorrhages?

HCM - managing asympto patient

Medication not ccurrently advised

HCM - approach to sympto case?

Same as asympto

• Confirm DX

• Look for underlying causes or factors that may worsen disease

Lifespan at B1?

1-10 yrs, very variable

HCM - Enlarged LA and prgonosis?

Enlarged LA is negative prognostic indcator - more likely to develop a thromus

HCM - B2 TX?

Clopidogrel or

rivaroxaban

HCM - C TX?

Frusemide, ACEI?

Clopidogrel/rivaroxaban

ACE has limited use

HCM - D TX?

Frusemide, ACEI? - ace has limited use

Clopidogrel/rivaroxaban

Pimobendan? - studies are a bit so-so

DCM and cats

Used to be the most common HD in felines until commercial food added taurine (previously taurine deficienct)

DX DCM?

TX?

Measure whole blood of Taurine - >250 nmol is deficient

Supp 250mg taurine PO if deficient

DCM - TX idiopathic DCM

• pIMOBENDAN

• fUROSEMIDE

• Ace inhibitor

• Low dose aspirin

DCM Prognosis

Taruine def - good if survive AHF

DCM not related to Taurine

• Poor

• Weeks to months left

Which is which?

1. Normal - normal chmaber vol

2. DCM - increased LV volume

3. HCM - reduced LV volume and enlarged Atria

4. RCM - Normal Ventricular Vol with enlarged atria

RCM - Restrictive cardiomyopathy

Features?

•Similar presentation to HCM

•Enlarged left atrium – LV not very thick

•Diastolic dysfunction on echo

•Prognosis similar – better if no respiratory distress on presentation

AHF CX?

•Dyspnoea

•Collapse

•Cyanosis

•Hindlimb paralysis?

AHF - DX assessment?

Minimal restraint

Quick auscultation

• Murmur?

• Crackles?

• Heart rate

• Pulse quality?

Thoracic rad if stable

Fast echo if stable

AHF TX?

•Furosemide

•Oxygen

•Anxiolytic

•Low dose aspirin

•Clopidogrel (FATCAT study)

•FAST heart scan or rad if stable

•If unsure if feline asthma a DD give a dose of an asthma pump - Avoid steroids (interfere with diagnostics)

Prophylaxis aspect?
Animals presents with?

Anti-coag advised by some

Hindlimb paralysis

Poor pulse in hindlimbs

Cold feet

May have cyanotic foot pads

Often in CHF when presented

Painful

AHF if CHF is present?

–Place on oxygen

–Give furosemide

–Low dose aspirin (25mg every 3 days)

–Or 18.75 mg Clopidogrel

–Heparin is another option

–Buprenorphine for pain

DD AHF?

Feline asthma - wheezing/crackles

Pleural effusion - muffled lung sounds

Non-cardiogenic oedema