Myocardial disease in Cats

Question 1

What is more common, myocardial or endocardial in cats?

Answer 1

Myocardial

Question 2

What types of myocardial disease do cats get?

Answer 2

Hypertrophic cardiomyopathy
Restrictive cardiomyopathy
Dilated cardiomyopathy (RARE)
Arrhythmogenic right ventricular cardiomyopathy (ARVC)
Feline unclassified cardiomyopathy (FUCM)

Question 3

Presentation of myocardial disease in cats

Answer 3

Often won’t show any clinical signs until in heart failure
* Dyspnoea - open mouth breathing
* Cyanosis

Question 4

What is HCM?

Answer 4

Hypertrophic cardiomyopathy
Concentric hypertrophy of ventricular myocardium
Left ventricle can’t dilate as usual

Question 5

How do you diagnose HCM?

Answer 5

Diagnosis of exclusion

Question 6

What else can cause concentric hypertrophy of ventricle myocardium?

Answer 6

Aortic stenosis (Ventricles struggle to eject blood so work harder and get bigger as a result)
Systemic hypertension (again ventricles have to pump harder to open aortic valve due to increased aortic pressure
* Diabetes mellitus
* Cushing’s
* Renal disease
Hyperthyroidism
Acromegaly

Question 7

What are the forms of HCM?

Answer 7

Obstructive (More common in dogs)
* Ventricular walls very thickened
* Systolic anterior motion of mitral valve
* Dynamic left ventricular outflow tract (LVOFT) obstruction
* Turbulent flow in aorta
* Concurrent eccentric jet of mitral regurgitation into LA

Non-obstructive
* Mitral valve doesn’t obstruct aorta

Question 8

Signalment of HCM

Answer 8

Cats most commonly (Rare in dogs)
Main coons/ragdolls
Older aged
Gallop sound or arrhythmia
NO murmur

Gallop sounds if serve HCM

Question 9

Echocardiography findings for HCM

Answer 9

Large LA diameter
Narrow LV
Thickened LV wall

Question 10

Types of restrictive cardiomyopathy

Answer 10

Endomyocardial (includes valve)
Myocardial (no valve)

Question 11

What is Restrictive cardiomyopathy

Answer 11

Extensive endocardial, subendocardial or myocardial fibrosis

• Atrial enlargement due to poor ventricular filling and regurgitation
• Mild LV hypertrophy can happen

Has same presentation as HCM
Diastolic (filling) failure

Question 12

Presentation of Restrictive cardiomyopathy

Answer 12

Very similar to HCM
Often as heart failure
Severe dyspnoea
Tachypnoea
Acute onset hindlimb lameness (aortic thromboembolism)
After fluid therapy. GA or steroid use

Question 13

Clinical signs of Restrictive cardiomyopathy

Answer 13

Ascites/plural effusion/pulmonary oedema
Hind limb paralysis
Often dynamic murmur
Crackles in lungs
Gallop sounds if serve HCM

Question 14

Echocardiography findings for RCM

Answer 14

LV hypertrophy with small lumen
LA dilation
Pericardial effusion
Hypertrophied, hyperechoic, irregular papillary muscles
Systolic anterior motion of the mitral valve (SAM)

Question 15

Radiography findings for RCM/HCM

Answer 15

Pleural effusion is quite common (LV thickened and puts pressure on RV to backs up into RA into vena cava)
Cardiomegaly
Venous congestion
Loveheart appearance <3 on DV

Question 16

Causes of Feline Dilated Cardiomyopathy

Answer 16

Taurine deficiency
Often endstage of another myocardial abnormality
(○ Toxic, Drug induced, CM, infection )
Similar to dogs - poor contractility, dilation of all 4 chambers