Valvular heart diseases Flashcards
What is the most common cardiac disease?
- Myxomatous degenerative valve disease - dogs, horses, pigs, humans
What dogs tend to get MDVD?
- Old dogs
- Small breeds
Acquired
What dogs tend to get mitral dysplasia?
- Young dogs
- Larger breeds
Congenital
What breed are predisposed to myxomatous mitral valve disease?
- Cavalier King Charles Spaniel
What is the gross pathology of MDVD?
- LA dilatation
- LV dilatation
- Elongation chordae tendinae
- Thickened leaflets
- Jet lesions
What happens with valve leaks?
- Leakage of blood back into atria (left most likely)
- Reduction in forward stroke volume = blood leaving the heart
- Increase in volume of blood entering left ventricle in next diastole = volume overload
What does neurohormonal activation cause on the sympathetic nervous system?
- Tachycardia
- Positive inotrope
- Vasoconstriction
What does neurohormonal activation cause on the RAAS?
- Retention of Na + fluid
- Increased circulatory system
- Vasoconstriction
What are sequalae of neurohormonal activation?
Sympathetic nervous system (tachycardia, vasoconstriction)
* Toxic for myocytes = intracellular Ca overload
* Increased oxygen demand
* Cell death, decrease in systolic function
RAAS
* Increased circulatory volume
* Increased hydrostatic pressures – congestion
Remodeling – eccentric hypertrophy
* Fibrosis (arrhythmias)
* Increased wall stress
* Dilatation of the valvular annulus = MR
How do you stage MDVD?
- A = at risk
- B1 = murmur + no enlargement
- B2 = murmur + enlargement - Pimobendan
- C1 = CHF - hospitalised - FPAS (Furosemide, pimobendan, ACE/SPiro)
- C2 = CHF - at home
- D1 = refractory - hospitalised
- D2 = refractory - at home
What is the most important thing to ask of consult?
- Exercise intolerance?
- Cough?
- Increased RR + effort?
What should be done on exam?
- Auscultation - murmur
- Blood pressure
- Clinical pathology (NTProBNP)
- Radiography
- ECG
- Echocardiography
What is troponin a marker for?
marker of myocyte damage
What is the most important diagnostic imaging in practice?
- Radiography - DV + right lateral, cardiac size, pulmonary vessels, effusions
If you can hear sinus arrhythmia what does this indicate?
- NOT in congestive heart failure
What does normal vs MDVD hearts look like on echo
- bullet shaped ventricle + smaller square atrium
- Tennis ball ventricle + massive atrium
What is the treatment of MDVD based on stages?
- A – none indicated, monitor at routine appointments
- B1 – none indicated, murmur will be present
- B2 – PIMOBENDAN
- C – CHF therapy as standard; Furosemide, pimobendan, ACEi, Spironolactone
- D – as for C with increasing doses and additional therapies e.g. sequential nephron blockade
What other treatments are there?
Arrhythmias
* Supraventricular = Diltiazem, Digoxin
* Ventricular = Sotalol, Mexilitine
Pulmonary hypertension
* Sildenafil
* Pimobendan
What is endocarditis?
- Infection of valve
- Mitral /aortic > tricuspid / pulmonic (In small animals)
- Staph, strep, E.coli, Pseudomonas
What is the pathology of endocarditis?
- Bacteraemia
- Damaged endothelium
- Ability to adhere
- Hypercoagulable states
What is diagnosed with echocardiography of endocarditis?
- Valvular vegetations
- Size = risk embolisation
- Regurgitation = MURMUR!
- Systolic dysfunction
Tx of endocarditis?
- Antibiotics - minimum 6 weeks
- Anticoagulation - clopidogrel / aspirin
- long term valvular damage
