Atrioventricular valve disease Flashcards
What are the two common forms of adult onset AV valve disease?
- ENdocardiosis (degeneration)
2. Endocarditis (infection)
What is the most common form of AV valve disease in dogs?
- Endocardiosis
What is the most common heart disease in the dog?
- Endocardiosis
What are four reasons that AV valves can be insufficient?
- Endocardiosis
- Endocarditis
- Dilation
- Dysplasia (congenital)
What do both endocardiosis and endocarditis ultimately result in?
- Insufficiency or incompetence of the AV valves
Does valvular insufficiency always equal valvular disease?
- NOPE
- Common secondary complications of ventricular enlargement as well
What can help you dfiferentiate the underlying cause of AV valve insufficiency?
- Signalment is super helpful
Pathophysiology of AV valvular insufficiency
- 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
Pathophysiology of CHF secondary to left AV valvular insufficiency
- Left atrial dilation/pressure
- Pulmonary venous pressure
- Pulmonary edema
AND
- cardiac output is limited
- Neurohormonal increase in RAAS
- Fluid retention (CHF)
Do animals always show progressive disease before getting CHF?
- Nope
Tricuspid valvular pathophysiology
- 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
Definition of AV valve endocardiosis
- Age related degenerative disease of the cardiac valves of dogs
- Myxomatous degeneration
- Valve accumulates glycosaminoglycans and become very nodular and globular looking
AV Valve degeneration in horses
- Horses develop it as well, but it is not referred to as endocardiosis
- Valve cups ocntract and become grossly distorted
Which valve gets distorted most frequently in horses?
- Aortic valve
Endocardiosis in cats and cattle
- Does not happen
Who gets endocardiosis?
- Older small/toy breed dogs
- Cavalier King Charles!!
Which valve is most often affected in endocardiosis?
- Mitral valve, most often
Incidence of endocardiosis in small dogs
- 30-40%
Endocardiosis in CKCS
- Often develops at a young age
- Familial nature apparent in many breeds
- Often progress to CHF or progress more quickly
What are key aspects of diagnosis for endocardiosis?
- Signalment and physical exam
Quality of the murmur for endocardiosis
- Systolic click, early stages
- Initially soft
- Progressively louder and holosystolic
- Flat or plateau character
- PMI is apical (mitral or tricuspid area)
- Murmur may radiate
Grade of murmur and severity of disease in valvular endocardiosis?
- DOES NOT CORRELATE TO SEVERITY OF DISEASE
What is the most important diagnostic test for AV endocardiosis?
- Thoracic radiographs
What can you evaluate with thoracic radiographs for AV endocardiosis?
- Degree of volume load/heart size
- Evaluate for possible congestion or CHF
Radiographic abnormalities with AV endocardiosis
- 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
ECG with mitral valve endocardiosis
- 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
Possible abnormalities with ECG
- P mitrale (wide P)
- Atrial fibrillation (indicates severe left atrial enlargement and irritation)
- SV (atrial) premature bet
- Tall R wave
Echocardiography changes for AV endocardiosis
- 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
Early impacts on contracility for mitral valve endocardiosis?
- Good contractility until quite late in disease
What type of hypertrophy happens with mitral valve regurgitation?
- Eccentric hypertrophy due to volume overload
Stage A endocardiosis definition
- Breeds at risk no murmur
- e.g. chihuahuas, Cavalier King Charles Spaniels
Stage A endocardiosis therapy
- None, monitor yearly
Stage B1 endocardiosis definition
- Minimal to no atrial enlargement
Stage B1 endocardiosis therapy
- Non, monitor q6-12 months with echocardiogram
- If a Cavalier or a breed at risk, probably monitor closer to 6 months
Stage B2 endocardiosis definition
- Moderate to severe atrial enlargement
Stage B2 endocardiosis therapy
- Pimobendan +/- Enalapril
Stage C endocardiosis definition
- Severe cardiomegaly, CHF
Stage C endocardiosis treatment
- Pimobendan
- Enalapril
- Furosemide
- diet changes
Stage D endocardiosis definition
- Refractory CHF
Stage D endocardiosis treatment
- Pimobendan, enalapril, furosemide, additional diuretics
Furosemide mechanism
- Diuretic
- Na/K/Cl channel inhibitor (Loop diuretic)
Furosemide purpose in CHF
- Diuretic to reduce pulmonary edema
Enalapril mechanism
ACE inhibitor
- Blocks conversion from Angiotensin I to Angiotensin II
Enalapril purpose
- Inhibit RAAS since you are giving Furosemide
Pimobendan mechanism
- Inodilator
- Calcium channel sensitizer
What should you give if there are atrial tachyarrhythmias or atrial fibrillation?
- Digoxin or diltiazem
MOA of Diltiazem
- Calcium channel blocker
What drug is contraindicated with CHF?
- Beta blockers
- Do NOT generally use a beta blocker
Effects of angiotensin II
- Increased thirst
- Increased aldosterone and subsequent increased Na and water
- Vasoconstriction
- Increased sympathetic tone
- Myocardial remodeling
MOA of Digoxin
- Blocks the sodium/potassium pump
- Will alternatively do a sodium/calcium exchanger
- Results in a rise of intracellular calcium
Mechanism of Dobutamine
- See the diagram in the notes
Prognosis for mitral valve endocardiosis
- 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)
Class C monitoring
- Every 2-6 months for left congestive heart failure (radiographs)
- Home respiratory rates
- Renal enzymes and blood pressure
What are two occasional complications with endocardiosis?
- Ruptured chordae tendonae
- Left atrial tear
Ruptured chordae tendonae
- Acute increase in amount of mitral valve regurgitation
- Acute, severe left heart failure
- Emergency situation
Left atrial tear
- 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
Valvular endocarditis - how common in dogs?
- Uncommon
Usual etiology of valvular endocarditis?
- Usually bacterial
- Rarely fungal or rickettsial organisms
Which valve is most commonly impacted by valvular endocarditis in horses and dogs?
- Aortic and mitral
Which valve is most commonly impacted by valvular endocarditis in cattle?
- Tricuspid and pulmonic
Which valve is most commonly impacted by valvular endocarditis in cats
- VERY RARE
- Don’t think of this at first in a cat with a murmur, even if they are sick
Factors for infection with endocarditis
- Hemodynamic
- Trauma to valve
- bacteremia source
- Virulence of bacteria
- Immunologic competence of host
Hemodynamic factor for infection with endocarditis
- turbulence of blood flow
- E.g. Subaortic stenosis, PDA, VSD, endocardiosis
Trauma factor for infection with endocarditis
- Trauma to the endocardial surface
- Exposure to collagen fibers allowing platelets and bacteria to adhere
Bacteremia factor for infection with endocarditis
- 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
Virulence of bacteria factor for infection with endocarditis
- Some bacteria able to adhere better and cause platelet aggregation better than others
Immunologic factors for infection with endocarditis
- Immunosuppression, antibody levels, and other issues of host competency are important
What are typical scenarios for endocarditis risk factors?
- Subaortic stenosis***
- GI or urinary tract infections
- Infected surgical implants
- Oncology patients
- Migrating foreign body
- Any cause of sepsis
What is usually recommended for at risk patients to reduce the risk for endocarditis?
- Prophylactic antibiotics
- 10 days for 2 weeks post
- For SAS patients, they will run them on antibiotics prior to the surgical procedures
Relationship between dental disease and endocarditis in dogs
- 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%
PE findings for endocarditis
- 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!***
CBC findings for endocarditis
- MAY include anemia, inflammatory leukogram
Serum biochemistry findings for endocarditis
- Azotemia, elevated serum globulins
Blood cultures for endocarditis
- Definitive diagnosis but often negative
Serology for endocarditis somewhat common findings
- Bartonella
Urinalysis for endocarditis
- Examine for pyuria
Urine culture and endocarditis
- Another way to do a blood culture
- Many infections originate or can simultaneously be present in the urinary system
Echocardiography and endocarditis
- Early lesions may not be detectable
- Valve lesions are thick, irregular hyperechoic masses
- Lesions (masses of fibrin, thrombi, and bacteria) may oscillate (vegetations)
Treatment for valvular endocarditis
- 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)
Prognosis for valvular endocarditis
- 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
