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Cardiovascular > Acquired CV disease of cats > Flashcards

Acquired CV disease of cats Flashcards

1
Q

Commonest acquired cardiac disease - CATS

A

Myocardial - i.e. cardiomyopathy
Congenital - less common
Primary arrhythmias - also less common
Primary valvular disease - extremely rare
Pericardial disease - much less common than dogs

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2
Q

Types of cardiomyopathy

A 
Same classification as humans:
****Hypertrophic - HCM****
Dilated - DCM
Restrictive - RCM
Arrhythmogenic - ARVC
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3
Q

Key features - HCM

A

Concentric LV hypertrophy (disatolic septum or free wall thickness > or equal to 6mm)
Poor LV relaxation
Stiff LV

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4
Q

Key features - DCM

A

Dilated LV with thin LV walls

Hypokinetic LV

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5
Q

Key features - RCM

A

Marked atrial dilation
No LV hypertrophy or dilation
Stiff LV

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6
Q

Key features - ARVC

A

Left heart relatively normal
Severe dilation of RA and RV
RV wall thinning

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7
Q

List examples of secondary myocardial disease

A

Hyperthyroid myocardial disease
Hypertensive myocardial disease
Cardiomyopathy secondary to hypersomatotropism (acromegaly)

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8
Q

When is it difficult to identify the original form of myocardial disease?

A

when pathological processes such as myocarditis or infarction are also present

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9
Q

Another name for HCM

A

Idiopathic (or genetic) left ventricular hypertrophyy (i.e. NOT due to systemic hypertension, aortic stenosis or hyperthyroidism)

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10
Q

Mutations - HCM

A

Human - usually associated with genetic mutations in sarcomeric proteins

Mutations in myosin binding protein C identified in Maine Coons and Ragdolls with HCM

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11
Q

Pathophysiology - HCM

A

MILD DISEASE: Impaired ventricular relaxation and increased ventricular stiffness. BOTH –> diastolic dysfunction

END STAGE: LA dilation, LA contractile dysfunction, LV systolic dysfunction (EFFECTS = increased atrial pressures, CHF, LA thrombus formation)

Also dynamic LVOTO

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12
Q

Define LVOTO

A

left ventricular outflow tract obstruction.

It describes the abnormal motion of the anterior mitral leaflet during systole (SAM)–> anterior leaflet moves towards OT during ejection –> OT obstruction and mitral regurgiatation –> worse with increased contractility, SNS stimulation or ventricular septal hypertrophy

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13
Q

Pathological findings - HCM

A

LV hypertrophy may affect any part of LV
LA dilates when filling pressures increased
Myocardial infarction may occur, appear as localised wall thinning with hypomobility and scarring.

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14
Q

Signalment - HCM

A

most common in young male adults
BUT all ages affected
Predisposition: maine coons, persians, ragdolls, cornish rexes and bengals. Most cats with HCM are moggies.

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15
Q

Presenting signs - HCM - 4

A

Asymptomatic - majority
Respiratory distress (CHF) - minority
HL paralysis due to ATE - minority
Sudden death - unknown prevalence

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16
Q

PE - HCM

A

** +/- variable intensity systolic murmur **
Prominent apical impulse
+/- gallop sounds (poor prognosis), arrhythmias
+/- tachypnoea, crackles
May be completely NORMAL

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17
Q

Radiography - HCM

A 
LV hypertrophy (long cardiac silhouette on lateral view)
Pulmonary oedema and/or pleural effusion (indicate CHF)
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18
Q

Echocardiography - HCM

A

LV hypertrophy = diastolic septal or free wall thickness greater than or equal to 6mm (focal or generalised)

SAM of mitral valve causes DLVOTO and murmur

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19
Q

Define SAM

A

Systolic anterior motion

20
Q

Define DLVOTO

A

Dynamic left ventricular outflow tract obstruction

21
Q

Prognosis - HCM

A

GOOD: short-medium term if LA normal size
POOR: if clinical signs present, LA enlargement, ATE

22
Q

Describe DCM

A

Dilation of all 4 chambers, with thinning of the ventricular walls and hypokinesis (systolic dysfunction). Historically associated with taurine deficiency. Now uncommon - most cats diagnosed have normal serum taurine levels.

23
Q

Clinical presentation - DCM

A

Middle-aged and older
Taurine-deficiency (if fed dog food)
Signs of output failure (hypotension, hypothermia, bradycardia)
Murmur quiet/absent but gallop often present
Thromboembolic disease - common

24
Q

Echocardiography - DCM - 3

A

Dilated, spherical LV
FS < 30%
LV end-systolic diameter >14mm

25
Q

Prognosis - DCM

A

Grave

26
Q

Outline RCM

A

Severely impaired diastolic filling
Stiff LV
Relatively normal LV dimensions and systolic function

27
Q

2 forms of RCM

A

Endomyocardial form - severe endomyocardial scarring such as a bridging scar across the LV.

Myocardial form - normal LV dimensions, non-infiltrative, patchy thickening of the LV walls

Severe atrial enlargement in both forms.

28
Q

Clinical presentation - RCM

A 
older cats
dyspnoea from pleural effusion common
\+/- low output signs
\+/- ATE
arrhythmias common
29
Q

Echocardiography - RCM

A

severe bilateral enlargement
Endomyocardial form of RCM is distinctive - endomyocardial scarring is readily imaged
Myocardial form is more challenging

30
Q

Outline ARVC

A

Arrhythmogenic right ventricular cardiomyopathy

Only recently characterised in cats - fibrofatty infiltration of the LV (scar tissue and adipose cells).
Marked right heart enlargement
May be asymptomatic
May be syncopal in association with arrhythmias
May have right-sided HF

31
Q

Echocardiography - ARVC

A

Severe RV and RA dilation

Tricuspid regurgitation usually present

32
Q

How is feline heart disease staged?

A 
A = predisposed
B1 = HCM, no CHF, normal LA
B2 = HCM, no CHF, big LA
C = HCM + CHF (past or present)
D = HCM + CHF despite treatment
33
Q

Treatment options - A - cats at risk of HCM

A

MBPC mutation test available - maine coons and ragdolls only
ANY cat could be at risk of HCM
Echocardiography provides a definitive diagnosis
Can consider NT-proBNP as initial step (>100picomols/litre)

34
Q

Treatment options - B - asymptomatic cats (HCM)

A

Some affected cats are at low risk for complications and don’t need treatment (no gallop, no arrhythmia, normal LA size, low NT-porBNP/troponin-I)

LVOTO - give a beta-blocker such as atenolol, may control the obstruction, currently no proven survival benefit, eases angina pain in humans

High risk cats (LA dilation, systolic dysfuction, extreme hypertrophy) - consider anti-thrombotic to reduce risk of ATE (e.g. clopidogrel is better than aspirin)

35
Q

What should you be aware of in cats with acute life-threatening HF?

A

Do everything to cause the least stress possible - echo is less stressful than radiographs

36
Q

Treatment - C - past or present HF

A

IMPROVE OXYGENATION:

Administer CO2 - oxygen cages practical

SEDATION: since dyspnoeic cats often become very distressed (butophanol sometimes works well)

IV FUROSEMIDE TO EFFECT: initial dose lower than dogs (2mg/kg) with subsequent doses (1-2mg/kg) every 60 mins until RR increases

THORACOCENTESIS: generally with a butterfly cannula

INCREASE CO: Difficult! If BP normal –> just treat
congestive signs. AVOID IV fluids - won’t increase CO and will worsen CHF.

37
Q

What are aims of home therapy for mild-moderate HF patients?

A

Eliminate abnormal fluid retention
Modulate neurohormonal activation
Optimise haemodynamic function
Prevent thromboembolism

38
Q

How do you eliminate fluid retention

A

FUROSEMIDE (1-4mg/kg q12-24 hours PO) - use to effect - decrease once congestive signs clear
ACEI - target dose of benazepril (0.5mg/kg q24 h)

39
Q

How can neurohormonal activation be modulated?

A

ACEI - benazepril preffered as licesned in cats - no evidence that abnormal hypertrophy is reveresed - Imidapril is difficult to pill cats with as it is a tasteless liquid.

40
Q

How can haemodynamic function be optimised?

A

Pimobendan if systolic dysfunction present

Otherwise v difficult to improve diastolic function

41
Q

Treatment - supraventricular tachycardia

A

Diltiazem

42
Q

What are the thoughts on using negative inotropes for dynamic obstruction?

A

Negative inotropes may decrease LVOTO gradients and beta-blockers are more effective at this than diltiazem in cats. However, negative inotropes may worsen CHF.

43
Q

Treatment - chronic refractory HF

A

If CHF persists despite therapy with furosemide and an ACEI, increase furosemide dose. If CHF continues desptite this, consider adding other diuretics:

Spironolactone - not licensed in cats - dosing similar to dogs - 1mg/kg q24h PO. Facial skin lesions

Thiazides - off label - combination used most commonly

For cats with systolic dysfunction, pimobendan can be added. Not licensed and should NOT be used in cats with DLVOTO.

44
Q

When may ATE occur?

A

any cardiomyopathy
particularly when the LA is dilated and poorly contractile

A thrombus usually forms in the left auricle and when disolodge dis ejected into the systemic circulation only to lodge in a peripheral artery. The commonest site is the distal aorta, but other sites include subclavian artery or a cerebral, renal or mesenteric artery.

CS: peracute and severe, with HL paresis and pain associated with obstruction of the terminal aorta.
Rate of survival to discharge <45%.
Underlying myocardial disease predisposing to TE cannot usually be resolved.

45
Q

Management - acute ATE - 5

A

Analgesia - methadone, fentanyl CRI
Manage electrolyte and acid-base abnormalities
Prevent thrombus extension - consider early use of clopidogrel
Pulses often return in 72h, thorough limb use longer (physio)
Thrombolysis can be associated with increased risk of reperfusion syndrome - therefore not usually attempted

46
Q

How can systemic TE be prevented? 4

A

Clopidogrel (superior to aspirin)
Aspirin (high or low dose)
Warfarin - not recommended
LMW-heparins - not recommended, costly, SC injection

Cardiovascular (22 decks)

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