AV Valve Disease

Question 1

Two common forms of adult onset AV Valve Disease

Answer 1

Endocardiosis (degeneration; more common)
Endocarditis (infection)

Both cause regurgitation

Question 2

Four reasons AV valves can be insufficient

Answer 2

Endocardiosis
Endocarditis
Insufficiency secondary to geometric changes of the ventricle
Congenital mitral or tricuspid dysplasia

Question 3

Pathophysiology of AV Valvular Insufficiency

Answer 3

Insufficiency = Regurgitation

Blood leaks back into the atrium as soon as the ventricular pressure exceeds the atrial pressure (systole)
LV has volume overload
LA will enlarge

Question 4

Pathophysiology of CHF due to AV Valvular Insufficiency

Answer 4

1. Left atrial dilation/pressure
2. Pulmonary venous pressure
3. Pulmonary edema (increase hydrostatic pressure) and CO is limited
4. Neurohormonal system activated (RAAS) to increase CO
5. Fluid retention (CHF)

Question 5

Pathophysiology of Tricuspid Valve Insufficiency

Answer 5

Cranial and caudal cava pressures increase:
Pleural effusion and/or hepatic venous congestion and ascites

Elevations of systemic venous pressures are also related to fluid retention from low CO

Question 6

AV Valve Endocardiosis

Answer 6

Age related degenerative disease of cardiac valves of the dog - valve cups become distorted

NO endocardiosis in cattle or cats

Question 7

Endocardiosis

Etilogy

Answer 7

Older small/toy breed dogs

Mitral valve

Cavalier King Charles Spaniels (can develop at a young age) -> genetics

Question 8

Endocardiosis

Physical Exam

Answer 8

Systolic murmur
Initially soft 
Progressively louder and holosystolic 
Flat or plateau character
PMI: apical (mitral or tricuspid) 
Murmur may radiate

Question 9

AV Endocardiosis

Radiographs

Answer 9

Important for diagnosis
Readily reveals degree of volume load/heart size
Evaluate possible congestion for CHF

May be normal even though there is a loud murmur
+/- LA enlargement
+/- LV enlargement
+/- left auricular bump
+/- Pulmonary venous congestion, pulmonary edema (interstitial pattern)

Question 10

Mitral Valve Endocardiosis

ECG

Answer 10

Potentially normal

May have evidence of LA or LV enlargement (Wide P wave or Tall R wave respectively)

May have arrhythmias due to dilated atria (atrial fibrillation, or supraventricular premature beat)

Note use echocardiogram to see regurgitation (mitral)

Question 11

AV Valve Endocardiosis Stage A

Answer 11

Breeds at risk, no murmur

Tx: None, monitor

Question 12

AV Valve Endocardiosis Stage B1

Answer 12

Minimal to no atrial enlargement

Murmur noted

Tx: None, monitor and re-check in 6 months

Question 13

AV Valve Endocardiosis Stage B2

Answer 13

Moderate to severe atrial enlargement

Rx: Pimobendan +/- Enalapril

Question 14

AV Valve Endocardiosis Stage C

Answer 14

CHF, severe cardiomegaly

Rx: Pimobendan, Enalapril (ACE-Inhibitor), Furosemide (pulmonary edema), diet

Question 15

AV Valve Endocardiosis Stage D

Answer 15

Refractory CHF

Rx: Pimobendan, Enalapril, Furosemide, diet

Question 16

AV Valve Endocardiosis with Atrial tachyarrhythmias

Answer 16

Add Digoxin or Ca channel blockers (diltiazem)

Avoid beta-blockers if CHF is present

Question 17

Mitral Valve Endocardiosis

Prognosis

Answer 17

Slowly progressive disease
CKCS will progress faster

1.5-2.5 years

Class C: monitor every 2-6 months

Question 18

Endocardiosis

Complications

Answer 18

Ruptured chordae tendonae:
Acute increase in mitral regurgitation (volume overload)
Acute, severe left heart failure
Emergency

Left atrial tear:
Acute hemo-pericardial effusion
Acute collapse due to decreased CO (heart is compressed)
Blood clot may form on tear and allow for temporary improvement
Treatment = pericardiocentesis

Question 19

AV Valve Endocardiosis

6 main points

Answer 19

1. Most common acquired heart disease in dogs
2. Small breeds of dogs
3. Mitral valve most commonly affected
4. Murmur does NOT correlate with severity
5. Clinical course can vary
6. Prognosis with therapy is good for several years

Question 20

Valvular endocarditis
What is it?
Species?

Answer 20

Can occur with endocardiosis

Infection of heart valve; usually bacterial (embolic bacteria)

Animal is SICK (usually systemic illness)

Horses: Aortic and mitral
Dogs (uncommon): Aortic and mitral
Cattle: Tricuspid and pulmonic
Cats: extremely rare

Question 21

Endocarditis Pathophysiology
(5 things)

Answer 21

1. Hemodynamic (regurgitation of turbulent flow; stenosis, PDA, VSD)
2. Trauma to valve (bacteria will adhere)
3. Bacteria source (GI tract -most common-, urinary, bone)
4. Virulence of bacteria
5. Immunologic competence of host (immunosuppressive drugs)

Question 22

Endocarditis Canine Risk Factors (6)

Answer 22

1. Subaortic stenosis
2. GI or Urinary tract infections
3. Infected surgical implants (orthopedics)
4. Oncology patients
5. Migrating foreign body
6. Any cause of sepsis

NO proven relationship between dental disease and Endocarditis

Question 23

Endocarditis

Echocardiography

Answer 23

Early lesions may not be detectable

Valve lesions are thick, irregular, hyperchoic

Lesions = masses of fibrin, thrombi and bacteria

Question 24

Endocarditis
Treatment
Prognosis

Answer 24

Antibiotics:
Based on blood culture ideally (urine could work as well because what is in urine is usually in blood)

IV antibiotics for 3-5 days

Oral or injectable antibiotics for 4-6 weeks

Prognosis:
Guarded to Poor
Usually succumb to heart failure
Permanent damage to valve