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Acquired valve disease Flashcards

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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

Study These Flashcards
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
What are thoracic radiographs used for in assessment of myxomatous mitral valve disease (MMVD)
Cardiac remodelling Pulmonary oedema Concurrent respiratory disease Point of future comparison
26
Assessment of cardiac remodelling on thoracic radiograph
Vertebral heart score general breed >=11.5 for general breed Vertebral left atrial size >= 3 Likely consistent with B2
27
Cardiac biomarkers
N-terminal pro brain natriutetic (NT-proBNP) Cardiac troponin I Limited use as standalone test
28
N-terminal pro brain natriuretic peptide (NT-proBNP)
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
Cardiac troponin I
Marker for myocardial cell damage Prognostic value Elevated in renal disease due to reduced elimination
30
ECG for myxomatous mitral valve disease (MMVD)
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
Clinical pathology for myxomatous mitral valve disease (MMVD)
Usually middle aged - older dogs should be screened for co-morbidities if treatment for CHF is anticipated
32
Systolic blood pressure for myxomatous mitral valve disease (MMVD)
Advisable to rule out concurrent systemic hypertension
33
Which SNAP antibody test should be used in the work up for a dog with cough, tachypnoea and/or exercise intolerance?
Angiostrongylus vasorum
34
Treatment of stage A myxomatous mitral valve disease (MMVD)
No treatment indicated SHould undergo yearly auscultation and may elect for annual cardiac screening
35
Treatment of stage B1 myxomatous mitral valve disease (MMVD)
No treatment indicated Repeat echocardiography advised in 6-12mo
36
Treatment for Stage B2 myxomatous mitral valve disease (MMVD)
Pimobendan
37
Pimobendan
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
Treatment of stage C and D myxomatous mitral valve disease (MMVD) with acute CHF
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
Treatment of stage C and D myxomatous mitral valve disease (MMVD) with chronic CHF
Pimobendan PO Diuretics - Furosemide PO - Torasemide PO ACE-i - Benazepril Spironolactone
40
Surgery for myxomatous mitral valve disease (MMVD)
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
Management of atrial fibrillation with MMVD
Digoxin Dilitiazem
42
Prognosis of myxomatous mitral valve disease (MMVD)
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
Infective endocarditis
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
Requirements for development of infective endocarditis
Transient or persistent bacteraemia Damaged endothelium Ability of bacteria to adhere and evade host defences Often a hypercoagulable state
45
Reported aetiological agents of infective endocarditis
Staphylococcus spp Streptococcus spp E. coli Pseudomonas aeruginosa Bartonella
46
Pathology of infective endocarditis
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
Pathophysiology of infective endocarditis
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
Diagnosis of infective endocarditis
Blood culture Clin path Echocardiography ECG
48
Presentation of infective endocarditis
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
Blood culture for infective endocarditis
Prior to antibiosis Aseptic technique Frequently negative Possible false positives
50
Clin path for infective endocarditis
Neutrophilia +/- left shift Thrombocytopaenia (risk DIC Renal or hepatic abnormalities associated with thromboembolic disease
51
Echocardiography for infective endocarditis
Presence of valvular vegetations Regurgitation across affected valve May result in systolic dysfuntion and CHF
52
ECG for infective endocarditis
Due to the risk of arrhythmias
53
Major criteria in the diagnosis of infective endocarditis
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
Minor criteria for the diagnosis of infective endocarditis
Fever (>39.4) Medium/large breed Subaortic stenosis Thromboembolic disease Immune mediated disease - polyarthritis - glolmerulonephritis Positive blood culture High Bartonella serology
55
How many of the criteria must a patient meet for a diagnosis of infective endocarditis to be made?
Definitive: 2 major OR 1 major + 2 minor OR 5 minor Presumed: 1 major + 1 minor OR 3 minor
56
Treatment of infective endocarditis
Bactericidal antibiotics - fluoroquinolone + potentiated amoxicillin + metronidazole - initially IV - minimum course 6 weeks Antithrombotics
57
Prognosis of infective endocarditis
Guarded - risk of recurrence - complications - irreversible valve damage

SA Cardiology (12 decks)

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