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Cardiology and Respiratory SA Med > Atrioventricular valve disease > Flashcards

Atrioventricular valve disease Flashcards

1
Q

What are the two common forms of adult onset AV valve disease?

A
  1. ENdocardiosis (degeneration)

2. Endocarditis (infection)

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2
Q

What is the most common form of AV valve disease in dogs?

A
  • Endocardiosis
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3
Q

What is the most common heart disease in the dog?

A
  • Endocardiosis
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4
Q

What are four reasons that AV valves can be insufficient?

A
  1. Endocardiosis
  2. Endocarditis
  3. Dilation
  4. Dysplasia (congenital)
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5
Q

What do both endocardiosis and endocarditis ultimately result in?

A
  • Insufficiency or incompetence of the AV valves
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6
Q

Does valvular insufficiency always equal valvular disease?

A
  • NOPE

- Common secondary complications of ventricular enlargement as well

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7
Q

What can help you dfiferentiate the underlying cause of AV valve insufficiency?

A
  • Signalment is super helpful
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8
Q

Pathophysiology of AV valvular insufficiency

A
  • Blood leaks backwards into the atrium as soon as the ventricular pressure exceeds the atrial pressure (AKA in systole)
  • Increased atrial size
  • Decreased forward stroke volume
  • Systolic plateau or flat murmur
  • Left ventricular dilation
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9
Q

Pathophysiology of CHF secondary to left AV valvular insufficiency

A
  1. Left atrial dilation/pressure
  2. Pulmonary venous pressure
  3. Pulmonary edema

AND

  1. cardiac output is limited
  2. Neurohormonal increase in RAAS
  3. Fluid retention (CHF)
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10
Q

Do animals always show progressive disease before getting CHF?

A
  • Nope
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11
Q

Tricuspid valvular pathophysiology

A
  • same on right side
  • Cranial and caudal vena cava pressures increase resulting in pleural effusion and/or hepatic venous congestion and ascites
  • Elevations of systemic venous pressures are also related to fluid retention from low cardiac output
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12
Q

Definition of AV valve endocardiosis

A
  • Age related degenerative disease of the cardiac valves of dogs
  • Myxomatous degeneration
  • Valve accumulates glycosaminoglycans and become very nodular and globular looking
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13
Q

AV Valve degeneration in horses

A
  • Horses develop it as well, but it is not referred to as endocardiosis
  • Valve cups ocntract and become grossly distorted
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14
Q

Which valve gets distorted most frequently in horses?

A
  • Aortic valve
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15
Q

Endocardiosis in cats and cattle

A
  • Does not happen
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16
Q

Who gets endocardiosis?

A
  • Older small/toy breed dogs

- Cavalier King Charles!!

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17
Q

Which valve is most often affected in endocardiosis?

A
  • Mitral valve, most often
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18
Q

Incidence of endocardiosis in small dogs

A
  • 30-40%
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19
Q

Endocardiosis in CKCS

A
  • Often develops at a young age
  • Familial nature apparent in many breeds
  • Often progress to CHF or progress more quickly
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20
Q

What are key aspects of diagnosis for endocardiosis?

A
  • Signalment and physical exam
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21
Q

Quality of the murmur for endocardiosis

A
  • Systolic click, early stages
  • Initially soft
  • Progressively louder and holosystolic
  • Flat or plateau character
  • PMI is apical (mitral or tricuspid area)
  • Murmur may radiate
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22
Q

Grade of murmur and severity of disease in valvular endocardiosis?

A
  • DOES NOT CORRELATE TO SEVERITY OF DISEASE
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23
Q

What is the most important diagnostic test for AV endocardiosis?

A
  • Thoracic radiographs
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24
Q

What can you evaluate with thoracic radiographs for AV endocardiosis?

A
  • Degree of volume load/heart size

- Evaluate for possible congestion or CHF

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25
Q

Radiographic abnormalities with AV endocardiosis

A
  • Depend on stage
  • May be normal even with severe heart murmur, early in disease
  • +/- left atrial enlargement
  • +/- left ventricular enlargement
  • +/- pulmonary venous congestion or pulmonary edema
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26
Q

ECG with mitral valve endocardiosis

A
  • May be normal
  • May have evidence of LA or LV enlargement
  • If you see a change, it’s there, but if you don’t see it, doesn’t mean it’s not
  • May have arrhythmias due to dilated atria
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27
Q

Possible abnormalities with ECG

A
  • P mitrale (wide P)
  • Atrial fibrillation (indicates severe left atrial enlargement and irritation)
  • SV (atrial) premature bet
  • Tall R wave
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28
Q

Echocardiography changes for AV endocardiosis

A
  • Thickened, irregular mitral valve or tricuspid valve
  • Valve may prolapse into the atrium
  • +/- left atrial enlargement
  • +/- left ventricular enlargement
  • +/- right atrial or ventricular enlargement
  • +/- systolic dysfunction
  • Mitral or tricuspid regurgitation can be seen on color Doppler
  • Good systolic function until very severe and chronic volume overload present
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29
Q

Early impacts on contracility for mitral valve endocardiosis?

A
  • Good contractility until quite late in disease
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30
Q

What type of hypertrophy happens with mitral valve regurgitation?

A
  • Eccentric hypertrophy due to volume overload
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31
Q

Stage A endocardiosis definition

A
  • Breeds at risk no murmur

- e.g. chihuahuas, Cavalier King Charles Spaniels

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32
Q

Stage A endocardiosis therapy

A
  • None, monitor yearly
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33
Q

Stage B1 endocardiosis definition

A
  • Minimal to no atrial enlargement
34
Q

Stage B1 endocardiosis therapy

A
  • Non, monitor q6-12 months with echocardiogram

- If a Cavalier or a breed at risk, probably monitor closer to 6 months

35
Q

Stage B2 endocardiosis definition

A
  • Moderate to severe atrial enlargement
36
Q

Stage B2 endocardiosis therapy

A
  • Pimobendan +/- Enalapril
37
Q

Stage C endocardiosis definition

A
  • Severe cardiomegaly, CHF
38
Q

Stage C endocardiosis treatment

A
  • Pimobendan
  • Enalapril
  • Furosemide
  • diet changes
39
Q

Stage D endocardiosis definition

A
  • Refractory CHF
40
Q

Stage D endocardiosis treatment

A
  • Pimobendan, enalapril, furosemide, additional diuretics
41
Q

Furosemide mechanism

A
  • Diuretic

- Na/K/Cl channel inhibitor (Loop diuretic)

42
Q

Furosemide purpose in CHF

A
  • Diuretic to reduce pulmonary edema
43
Q

Enalapril mechanism

A

ACE inhibitor

  • Blocks conversion from Angiotensin I to Angiotensin II
44
Q

Enalapril purpose

A
  • Inhibit RAAS since you are giving Furosemide
45
Q

Pimobendan mechanism

A
  • Inodilator

- Calcium channel sensitizer

46
Q

What should you give if there are atrial tachyarrhythmias or atrial fibrillation?

A
  • Digoxin or diltiazem
47
Q

MOA of Diltiazem

A
  • Calcium channel blocker
48
Q

What drug is contraindicated with CHF?

A
  • Beta blockers

- Do NOT generally use a beta blocker

49
Q

Effects of angiotensin II

A
  • Increased thirst
  • Increased aldosterone and subsequent increased Na and water
  • Vasoconstriction
  • Increased sympathetic tone
  • Myocardial remodeling
50
Q

MOA of Digoxin

A
  • Blocks the sodium/potassium pump
  • Will alternatively do a sodium/calcium exchanger
  • Results in a rise of intracellular calcium
51
Q

Mechanism of Dobutamine

A
  • See the diagram in the notes
52
Q

Prognosis for mitral valve endocardiosis

A
  • usually slowly progressive (over years)
  • Some dogs will never progress (approximately half)
  • Some breeds progress faster (CKCS)
  • Prognosis good with successful treatment of CHF (~1.5-2.5 years)
53
Q

Class C monitoring

A
  • Every 2-6 months for left congestive heart failure (radiographs)
  • Home respiratory rates
  • Renal enzymes and blood pressure
54
Q

What are two occasional complications with endocardiosis?

A
  • Ruptured chordae tendonae

- Left atrial tear

55
Q

Ruptured chordae tendonae

A
  • Acute increase in amount of mitral valve regurgitation
  • Acute, severe left heart failure
  • Emergency situation
56
Q

Left atrial tear

A
  • Acute hemo-pericardial effusion
  • Acute collapse due to decreased dcardiac output
  • Blood clot may form on tear and allow for temporary improvement
  • Treatment is careful pericardiocentesis
  • May have rapid death
  • Can go into hypotensive shock
57
Q

Valvular endocarditis - how common in dogs?

A
  • Uncommon
58
Q

Usual etiology of valvular endocarditis?

A
  • Usually bacterial

- Rarely fungal or rickettsial organisms

59
Q

Which valve is most commonly impacted by valvular endocarditis in horses and dogs?

A
  • Aortic and mitral
60
Q

Which valve is most commonly impacted by valvular endocarditis in cattle?

A
  • Tricuspid and pulmonic
61
Q

Which valve is most commonly impacted by valvular endocarditis in cats

A
  • VERY RARE

- Don’t think of this at first in a cat with a murmur, even if they are sick

62
Q

Factors for infection with endocarditis

A
  1. Hemodynamic
  2. Trauma to valve
  3. bacteremia source
  4. Virulence of bacteria
  5. Immunologic competence of host
63
Q

Hemodynamic factor for infection with endocarditis

A
  • turbulence of blood flow

- E.g. Subaortic stenosis, PDA, VSD, endocardiosis

64
Q

Trauma factor for infection with endocarditis

A
  • Trauma to the endocardial surface

- Exposure to collagen fibers allowing platelets and bacteria to adhere

65
Q

Bacteremia factor for infection with endocarditis

A
  • Circulating, even for short periods
  • Portal may include breaks in the GIT (aka bacterial translocation), or from bone infections or urogenital infections
  • Iatrogenic can include infected IV lines or surgical procedures
66
Q

Virulence of bacteria factor for infection with endocarditis

A
  • Some bacteria able to adhere better and cause platelet aggregation better than others
67
Q

Immunologic factors for infection with endocarditis

A
  • Immunosuppression, antibody levels, and other issues of host competency are important
68
Q

What are typical scenarios for endocarditis risk factors?

A
  1. Subaortic stenosis***
  2. GI or urinary tract infections
  3. Infected surgical implants
  4. Oncology patients
  5. Migrating foreign body
  6. Any cause of sepsis
69
Q

What is usually recommended for at risk patients to reduce the risk for endocarditis?

A
  • Prophylactic antibiotics
  • 10 days for 2 weeks post
  • For SAS patients, they will run them on antibiotics prior to the surgical procedures
70
Q

Relationship between dental disease and endocarditis in dogs

A
  • NO proven relationship to dental disease in the dog
  • Incidence of dental disease >90%
  • Incidence of mitral valve endocardiosis in dogs is ~40%
  • Incidence of endocarditis is ~1%
71
Q

PE findings for endocarditis

A
  • Fever (may be intermittent)
  • New heart murmur or different murmur
  • +/- tachycardia, bounding pulses (if aortic regurgitation), arrhythmia (myocarditis or systemic inflammation), signs of CHF, Tachypnea (CHF, pneumonia)
  • Evidence of systemic illness!***
72
Q

CBC findings for endocarditis

A
  • MAY include anemia, inflammatory leukogram
73
Q

Serum biochemistry findings for endocarditis

A
  • Azotemia, elevated serum globulins
74
Q

Blood cultures for endocarditis

A
  • Definitive diagnosis but often negative
75
Q

Serology for endocarditis somewhat common findings

A
  • Bartonella
76
Q

Urinalysis for endocarditis

A
  • Examine for pyuria
77
Q

Urine culture and endocarditis

A
  • Another way to do a blood culture

- Many infections originate or can simultaneously be present in the urinary system

78
Q

Echocardiography and endocarditis

A
  • Early lesions may not be detectable
  • Valve lesions are thick, irregular hyperechoic masses
  • Lesions (masses of fibrin, thrombi, and bacteria) may oscillate (vegetations)
79
Q

Treatment for valvular endocarditis

A
  • Antibiotics (ideally based on blood culture results and urine culture)
  • IV abx for 3-5 days to penetrate fibrin
  • Oral or injectable antibiotics for 4-6 weeks (in SA or horses)
80
Q

Prognosis for valvular endocarditis

A
  • Overall guarded to poor
  • Permanent valvular lesions and dysfunction persist
  • Majority of animals succumb to heart failure or secondary embolic complications
  • Mitral valve endocarditis better prognosis than aortic endocarditis

Cardiology and Respiratory SA Med (15 decks)

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