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Cardiology > Acquired valve disease > Flashcards

Acquired valve disease Flashcards

1
Q

Aetiology of myxomatous mitral valve disease (MMVD)

A

Cause unknown

Inherited component in some breeds (CKCS, Dachshund)

Presumed to be familial in other breeds

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2
Q

Pathology of myxomatous mitral valve disease (MMVD)

A

Nodular thickening of the mitral valve leaflets

Abnormalities in collagen content and alignment and expansion of the spongiosa due to accumulation of proteoglycans

Prolapse of the mitral valve into the left atrium is commonly seen

Progressive deformation of the valve apparatus leads to ineffective coaptation and consequent regurgitation

Grossly seen as deformed, thickened valve leaflets and elongation of the chordae tendinae

Jet lesions (impact lesions) may be seen on the mitral endocardium secondary to severe mitral regurgitation

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3
Q

Pathophhysiology of myxomatous mitral valve disease (MMVD)

A

Chronic left-sided volume overload

Mitral regurg results in an increase in preload and the compensatory response - eccentric hypertrophy of the left ventricle

progressive increase in left ventricular and atrial size

Severe disease can lead to pulmonary oedema

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4
Q

Concentric hypertrophy

A

Reduced ventricular volume

Thickened walls

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5
Q

Eccentric hypertrophy

A

Increased ventricular volume

Also with thickened walls

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6
Q

Sequelae of myxomatous mitral valve disease (MMVD)

A

Left sided congestive heart failure (pulmonary oedema)

Arrhythmias - especially atrial fibrillation (may result in right sided CHF)

Left atrial tears/acquired septal defects

Pulmonary hypertension

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7
Q

Stages of myxomatous mitral valve disease (MMVD)

A

A: predisposed/at risk

B: pre-clinical disease
B1: MR but no/minimal secondary remodelling
B2: LA and LV dilation

C: CHF

D: refractory CHF

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8
Q

Stage A myxomatous mitral valve disease (MMVD)

A

Dogs considered at increased risk but without apparent structural abnormalities

E.g. CKCS

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9
Q

Stage B myxomatous mitral valve disease (MMVD)

A

Dogs with structural heart disease but no evidence of CHF i.e. pre-clinical MMVD

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10
Q

Stage B1 myxomatous mitral valve disease (MMVD)

A

Asymptomatic MMVD but with no radiographic or echocardiographic evidence of cardiac remodelling

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11
Q

Stage B2 myxomatous mitral valve disease (MMVD)

A

Asymptomatic MMVD which is haemodynamically severe enough, and present for long enough to induce cardiac remodelling (left atrial and ventricular dilation) identified on radiographs +/- echocardiography

Murmur at least grade 3

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12
Q

Stage C myxomatous mitral valve disease (MMVD)

A

DOgs with MMVD and CHF (either controlled or current decompensated)

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13
Q

Stage D myxomatous mitral valve disease (MMVD)

A

Dogs with end-stage MMVD with CHF refractory to standard treatment

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14
Q

Signalment of myxomatous mitral valve disease (MMVD)

A

Middle aged to older dogs

Small breed dogs typically under 20kg

Can develop in any breed and may progress quicker in large breed dogs

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15
Q

History of pre-clinical (stage B) myxomatous mitral valve disease (MMVD)

A

Most will be asymptomatic

If advanced (B2) left atrial dilation may cause compression of the caudal mainstem bronchi and consequent chronic cough

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16
Q

History of clinical disease (stage C; CHF) myxomatous mitral valve disease (MMVD)

A

Chronic murmur

Elevated resp rate or effort

Cough

Reduced exercise capacity

Weight loss, muscle loss, reduced appetite, lethargy

Abdominal distension if right sided CHF

Collapse/syncope (less common)

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17
Q

Physical examination of pre-clinical (stage B) myxomatous mitral valve disease (MMVD)

A

Left apical systolic murmur

Concurrent right apical murmurs

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18
Q

Physical examination of clinical (stage C) myxomatous mitral valve disease (MMVD)

A

Left apical systolic murmur and concurrent right apical murmur

Tachypnoea +/- dyspnoea

Pulmonary crackles

Tachycardia, tachyarrhythmias

Signs of right-sided CHF less common

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19
Q

Signs of right sided heart failure

A

Jugular distension

Positive hepatojugular reflux

Abdominal distension with fluid thrill

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20
Q

Echocardiography of stage B1 myxomatous mitral valve disease (MMVD)

A

Mitral valve leaflets are abnormal

Evidence of mitral regurgitation

Left atrium and left ventricle are normal (or near normal) in size

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21
Q

Echocardiography of stage B2 myxomatous mitral valve disease (MMVD)

A

Abnormal mitral valve leaflets with mitral regurg and secondary dilation of the left atrium AND left ventricle

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22
Q

Echocardiography of stage C myxomatous mitral valve disease (MMVD)

A

As B2 but more severe mitral regurg and left sided dilation

Evidence of elevated pressures within the left atrium

B lines may be seen

Look for evidence of atrial tears and right sided CHF (less common)

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23
Q

Assessment of left atrial size on echo

A

Right parasternal short axis view of the heart base

Left atrial diameter is normalised to the aorta (LA:Ao)

Cut off is 1.6 or more

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24
Q

Assessment of left ventricular size

A

Several different measurements including both linear dimensions and volumes

Diagnosis of B2 MMVD a left ventricular internal diameter measured from a short axis M-mode, more than or equal to 1.7 is used as a cut off

25
Q

What are thoracic radiographs used for in assessment of myxomatous mitral valve disease (MMVD)

A

Cardiac remodelling

Pulmonary oedema

Concurrent respiratory disease

Point of future comparison

26
Q

Assessment of cardiac remodelling on thoracic radiograph

A

Vertebral heart score general breed >=11.5 for general breed

Vertebral left atrial size >= 3

Likely consistent with B2

27
Q

Cardiac biomarkers

A

N-terminal pro brain natriutetic (NT-proBNP)

Cardiac troponin I

Limited use as standalone test

28
Q

N-terminal pro brain natriuretic peptide (NT-proBNP)

A

Released by ventricular stretch

Increases in volume with increasing severity of volume overload of the left heart

A normal or near normal NT-proBNP in a patient with signs of CHF (coughm dyspnoea etc) is unlikely to have CHF

External lab so not useful for emergency

29
Q

Cardiac troponin I

A

Marker for myocardial cell damage

Prognostic value

Elevated in renal disease due to reduced elimination

30
Q

ECG for myxomatous mitral valve disease (MMVD)

A

Low sensitivity for detection of cardiac remodelling

Sinus arrhythmia indicates predominance of parasympathetic system making decompensated CHF unlikely

Sinus tachycardia indicates sympathetic elevation - may be stress or decompensated disease

Advanced MMVD may see supraventricular and ventricular arrhythmias

Atrial fibrillation can be seen secondary to severe left atrial dilation

31
Q

Clinical pathology for myxomatous mitral valve disease (MMVD)

A

Usually middle aged - older dogs should be screened for co-morbidities if treatment for CHF is anticipated

32
Q

Systolic blood pressure for myxomatous mitral valve disease (MMVD)

A

Advisable to rule out concurrent systemic hypertension

33
Q

Which SNAP antibody test should be used in the work up for a dog with cough, tachypnoea and/or exercise intolerance?

A

Angiostrongylus vasorum

34
Q

Treatment of stage A myxomatous mitral valve disease (MMVD)

A

No treatment indicated

SHould undergo yearly auscultation and may elect for annual cardiac screening

35
Q

Treatment of stage B1 myxomatous mitral valve disease (MMVD)

A

No treatment indicated

Repeat echocardiography advised in 6-12mo

36
Q

Treatment for Stage B2 myxomatous mitral valve disease (MMVD)

A

Pimobendan

37
Q

Pimobendan

A

Phosphodiesterase III inhibitor

Calcium sensitisation

Positive inotrope

Arterial and venous dilator

In dogs: proven benefit in both MMVD and DCM

Contraindications: fixed outflow tract obstruction

38
Q

Treatment of stage C and D myxomatous mitral valve disease (MMVD) with acute CHF

A

Oxygen

Furosemide IV (CRI after inital bolus)

Pimobendan PO (hopefully already started)

Sedation/anti-anxiety (butorphanol)

maybe also:
- vasodilators
- further inotropic support
- mechanical ventilation

39
Q

Treatment of stage C and D myxomatous mitral valve disease (MMVD) with chronic CHF

A

Pimobendan PO

Diuretics
- Furosemide PO
- Torasemide PO

ACE-i
- Benazepril

Spironolactone

40
Q

Surgery for myxomatous mitral valve disease (MMVD)

A

Surgical valve repair performed under cardiac bypass surgery for stage C dogs
- Very expensive and few places do it

Hybrid surgical interventions not requiring bypass becoming more widely used/available

41
Q

Management of atrial fibrillation with MMVD

A

Digoxin

Dilitiazem

42
Q

Prognosis of myxomatous mitral valve disease (MMVD)

A

Usually a long course of disease with slow progression

Once in CHF, median survival times are typically 9-12mo

Large breed dogs may be more likely to develop myocardial failure and/or arrhythmias and deteriorate more quickly

43
Q

Infective endocarditis

A

Uncommon in small animals

Caused by bacterial infection of the endocardial surfaces - most likely on the mitral or aortic valves

Should be suspected in cases of pyrexia of unknown origin

Murmur is not always present

44
Q

Requirements for development of infective endocarditis

A

Transient or persistent bacteraemia

Damaged endothelium

Ability of bacteria to adhere and evade host defences

Often a hypercoagulable state

45
Q

Reported aetiological agents of infective endocarditis

A

Staphylococcus spp

Streptococcus spp

E. coli

Pseudomonas aeruginosa

Bartonella

46
Q

Pathology of infective endocarditis

A

Vegetations on the endocardial surface of the valve leaflets

Vegetations range from small nodules to large coalescing lesions

Made up of platelets, RBC, bacteria, fibrin

Mature lesions may have dense fibrous tissue and calcification

47
Q

Pathophysiology of infective endocarditis

A

Bacteraemia leads to activation of a systemic inflammatory response

High risk of thromboembolic events

Stimulation of humoral/cellular immune system results in immune complex deposition and subsequent clotting abnormalities

48
Q

Diagnosis of infective endocarditis

A

Blood culture

Clin path

Echocardiography

ECG

48
Q

Presentation of infective endocarditis

A

Medium to large breed dogs over-represented

Concurrent pathology creates risk factor

Pyrexia of unknown origin, systemic embolisation, or activation of the immune system

Cardiac clinical signs may be:
- new or changed murmur
- arrhythmias
- CHF

49
Q

Blood culture for infective endocarditis

A

Prior to antibiosis

Aseptic technique

Frequently negative

Possible false positives

50
Q

Clin path for infective endocarditis

A

Neutrophilia +/- left shift

Thrombocytopaenia (risk DIC

Renal or hepatic abnormalities associated with thromboembolic disease

51
Q

Echocardiography for infective endocarditis

A

Presence of valvular vegetations

Regurgitation across affected valve

May result in systolic dysfuntion and CHF

52
Q

ECG for infective endocarditis

A

Due to the risk of arrhythmias

53
Q

Major criteria in the diagnosis of infective endocarditis

A

Positive echocardiography - vegetative, oscillating lesions

New valvular insufficiency

Positive blood vultire
- at least 2 positive cultures
- at least 3 positive cultures if possible skin contaminant

54
Q

Minor criteria for the diagnosis of infective endocarditis

A

Fever (>39.4)

Medium/large breed

Subaortic stenosis

Thromboembolic disease

Immune mediated disease
- polyarthritis
- glolmerulonephritis

Positive blood culture

High Bartonella serology

55
Q

How many of the criteria must a patient meet for a diagnosis of infective endocarditis to be made?

A

Definitive: 2 major OR 1 major + 2 minor OR 5 minor

Presumed: 1 major + 1 minor OR 3 minor

56
Q

Treatment of infective endocarditis

A

Bactericidal antibiotics
- fluoroquinolone + potentiated amoxicillin + metronidazole
- initially IV
- minimum course 6 weeks

Antithrombotics

57
Q

Prognosis of infective endocarditis

A

Guarded
- risk of recurrence
- complications
- irreversible valve damage

Cardiology (10 decks)

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