AV Valve Disease Flashcards
Exam IV
Two common forms of adult onset AV Valve Disease
Endocardiosis (degeneration; more common)
Endocarditis (infection)
Both cause regurgitation
Four reasons AV valves can be insufficient
Endocardiosis
Endocarditis
Insufficiency secondary to geometric changes of the ventricle
Congenital mitral or tricuspid dysplasia
Pathophysiology of AV Valvular Insufficiency
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
Pathophysiology of CHF due to AV Valvular Insufficiency
- Left atrial dilation/pressure
- Pulmonary venous pressure
- Pulmonary edema (increase hydrostatic pressure) and CO is limited
- Neurohormonal system activated (RAAS) to increase CO
- Fluid retention (CHF)
Pathophysiology of Tricuspid Valve Insufficiency
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
AV Valve Endocardiosis
Age related degenerative disease of cardiac valves of the dog - valve cups become distorted
NO endocardiosis in cattle or cats
Endocardiosis
Etilogy
Older small/toy breed dogs
Mitral valve
Cavalier King Charles Spaniels (can develop at a young age) -> genetics
Endocardiosis
Physical Exam
Systolic murmur Initially soft Progressively louder and holosystolic Flat or plateau character PMI: apical (mitral or tricuspid) Murmur may radiate
AV Endocardiosis
Radiographs
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)
Mitral Valve Endocardiosis
ECG
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)
AV Valve Endocardiosis Stage A
Breeds at risk, no murmur
Tx: None, monitor
AV Valve Endocardiosis Stage B1
Minimal to no atrial enlargement
Murmur noted
Tx: None, monitor and re-check in 6 months
AV Valve Endocardiosis Stage B2
Moderate to severe atrial enlargement
Rx: Pimobendan +/- Enalapril
AV Valve Endocardiosis Stage C
CHF, severe cardiomegaly
Rx: Pimobendan, Enalapril (ACE-Inhibitor), Furosemide (pulmonary edema), diet
AV Valve Endocardiosis Stage D
Refractory CHF
Rx: Pimobendan, Enalapril, Furosemide, diet
AV Valve Endocardiosis with Atrial tachyarrhythmias
Add Digoxin or Ca channel blockers (diltiazem)
Avoid beta-blockers if CHF is present
Mitral Valve Endocardiosis
Prognosis
Slowly progressive disease
CKCS will progress faster
1.5-2.5 years
Class C: monitor every 2-6 months
Endocardiosis
Complications
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
AV Valve Endocardiosis
6 main points
- Most common acquired heart disease in dogs
- Small breeds of dogs
- Mitral valve most commonly affected
- Murmur does NOT correlate with severity
- Clinical course can vary
- Prognosis with therapy is good for several years
Valvular endocarditis
What is it?
Species?
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
Endocarditis Pathophysiology (5 things)
- Hemodynamic (regurgitation of turbulent flow; stenosis, PDA, VSD)
- Trauma to valve (bacteria will adhere)
- Bacteria source (GI tract -most common-, urinary, bone)
- Virulence of bacteria
- Immunologic competence of host (immunosuppressive drugs)
Endocarditis Canine Risk Factors (6)
- Subaortic stenosis
- GI or Urinary tract infections
- Infected surgical implants (orthopedics)
- Oncology patients
- Migrating foreign body
- Any cause of sepsis
NO proven relationship between dental disease and Endocarditis
Endocarditis
Echocardiography
Early lesions may not be detectable
Valve lesions are thick, irregular, hyperchoic
Lesions = masses of fibrin, thrombi and bacteria
Endocarditis
Treatment
Prognosis
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
