Feline Myocardial Disease

Question 1

Cardiomyopathies

Answer 1

Diseases affecting the heart muscle with unknown/ uncertain etiology

Question 2

ACVIM Cardiology consensus staging

Answer 2

A: predisposed (genetic/congenital)
B1 (low risk): subclinical- normal/ mild atrial enlargement
B2: (higher risk): subclinical- moderate to severe atrial enlargement
C: current/ previous CHF/ atrial thoraco embolism
D: refractory CHF

Question 3

Hypertrophic cardiomyopathy

Answer 3

Most common acquired heart dz in cats
Concentric hypertrophy asymmetrical or generalized ( maine coon, shorthair)
Obstructive/ HOCM (murmurs)and non/ HCM forms

Question 4

Genetics of HCM

Answer 4

Mutations in genes that encode proteins of the cardiac sarcomere → phenotypic HCM

Question 5

Breed predispostion of HCM

Answer 5

Maine coon and ragdoll

Question 6

Maine coon and ragdoll

Answer 6

Mutation of myosin-binding protein C (30%)
Most cats that are heterozygous for mutation won’t get sick
Homozygous= sick after 3y of age (maine coon), 1-2y old (ragdoll)

Question 7

HCM pathophysiology

Answer 7

Diastolic dysfunction (↑ LV relaxation, LA pressure, and LV filling pressure)
Thromboembolic events
Arrhythmias secondary to ischemia

Question 8

Signalment of cats with HCM

Answer 8

Most between 4-7y
Male predominance

Question 9

CS associated with HCM

Answer 9

Often normal
Signs of L-CHF (rarely cough)
Systemic arterial thromboembolism
Syncope, sudden death from arrythmias

Question 10

What’s seen on a PE of a cat with HCM

Answer 10

Auscultation (S4 gallop, systolic murmur)
CHF: resp. ditress

Question 11

Most murmurs associated with HCM

Answer 11

Systolic
L-or-right parasternal

Question 12

What causes a mumur with HCM

Answer 12

Dynamic left outflow tract obstruction/ systolic anterior motion of the mitral valve (SAM)
HOCM

Question 13

HCM thoracic rads

Answer 13

Modest cardiomegaly
Bi-atrial enlargement
Pulm. venous congestion/ edema, pleural effusion

Question 14

HCM ECG

Answer 14

Concentric hypertrophy of LV
LA dilation +/- thormbi
DSAS from SAM (obstructive)
Abnormal LV filling pattern

Question 15

DX HCM

Answer 15

Dx of exclusion (rule out physiologic causes of concentric hypertrophy- hyperthyroid, hypertension and obstruction)
ProBNP (confirm with echo, helpful if - or slightly elevated)

Question 16

Clin path of HCM

Answer 16

↑ CK, LDH and AST with emboli
K+ with reperfusion
Myofiber disarray

Question 17

Tx of HCM (asymptomatic)

Answer 17

No tx (A-B1)
Beta-blocker in case of HOCM (atenolol)

Question 18

Emergency tx for dyspneic patient with HCM

Answer 18

FOT: furosemide, oxygen then thoracocentesis (if pleural effusion)
Nitroglycerin ointment

Question 19

Clinical management for HCM

Answer 19

Chr. oral therapy:
ACE inhibitors and diuretics (stage C-D)
Beta-blockers (complete HOCM)
Anticoagulant therapy (advanced B2-D)

Question 20

Restrictive cardiomyopathy phenotype

Answer 20

Restrictive LV filling
Myocardial (idiopathic, non-infiltrative) and endomyocardial forms

Question 21

Pathophysiology of restrictive cardiomypathy phenotype

Answer 21

Impaired diastolic filling
Severely dilated atria (mickey mouse heart)

Question 22

Thryrotoxic cardiomyopathy

Answer 22

Hyperthyroidism: tropic effect →hypertrophy and tachycardia
focus on treating the underlying hyperthyroidism

Question 23

What’s seen with Thyrotoxic cardiomyopathy ?

Answer 23

Arrhythmias, DSAS, DSPS
High output, vol expansion: systolic pump failure and high output heart failure

Question 24

Dilated cardiomyopathy phenotype

Answer 24

Dietary taurine deficiency
Left ventricular eccentric hypertrophy
Decreased systolic function

Question 25

How to tx DCM

Answer 25

Taurine supplements
Pimobedan (systolic dysfunction)
Placid for thromboprophylaxis
Standard therapy for CHF

Question 26

Thrombus formation

Answer 26

Left atrial formation (LA)
Virchow’s triad (hypercoagulable state, endothelial injury, blood stasis)

Question 27

Thrombus formation on U/S

Answer 27

Spontaneous echogenic contrast “smoke”
Increased blood echogencity (RBC aggregates)
Forms under low flow conditions
Marker of a prothombotic state

Question 28

Thromboembolism in feline cardiomyopathies

Answer 28

Risk of thrombus formation in dilated atrium or distal aorta (saddle thrombus)
Acute paresis

Question 29

Ischemic neuropathy

Answer 29

Activated platelets within the the thromboembolism →release vasoactive substance → serotonin and thromboxane A2→ collateral vasoconstriction

Question 30

CS of thromboembolism

Answer 30

Acute hindlimb, pain, cold extremities, absence of femoral pulses, shock and hypothermia, dyspnea from pain or CHF

Question 31

Dx of thromboembolism

Answer 31

Auscultation: murmur, gallop, arrhythmia, normal
Rads
Echocardiogram

Question 32

Managing thromboembolism

Answer 32

Pain management (opioid)
CHF management
Limited thrombus progression (alter coagulation- heparin and decrease platelet aggregation- plavix)
Oral direct Xa inhibitors (rivaroxaban ans apixaban)

Question 33

Plavix (clopidogrel)

Answer 33

Prevents platelet aggregation, protects collateral circulation
Decreased risk of 2nd thromboembolic event

Question 34

Risk if perfusion

Answer 34

12-24 hrs after thromboembolism
Reperfusion of ischemic tissue
Release of K+ in the blood stream
Hyperkalemia

Question 35

Further consequences of hyperkalemia

Answer 35

Bradycardia, ventricular arrhythmias (risk of sudden death)
Tx: rapid acting insuline + dextrose