Valvular disease (Yr 4)

Question 1

what dogs present with myxomatous mitral valve disease?

Answer 1

older small breed dogs (CKCS)

Question 2

what is the pathogenesis of myxomatous degenerative valvular disease?

Answer 2

proteoglycan accumulation causes nodular thickening of valve leaflets leading to stretch/rupture of chordae tendinae causing leakage

Question 3

what is the aetiology of MDVD?

Answer 3

idiopathic (genetic)

Question 4

what is the gross pathology associated with MDVD?

Answer 4

thickened valvular leaflets
elongated/thickened chordae tendinae
eccentric hypertrophy (LA/LV)
jet lesions

Question 5

why does the regurgitant flow of the mitral valve cause hypertrophy?

Answer 5

regurgitant flow back into the atria reduces left sided stroke volume
increased blood volume enters the left ventricle during the next diastole
resulting in volume overload (eccentric hypertrophy)

Question 6

what does the reduced stroke volume associated with MDVD trigger?

Answer 6

sympathetic nervous system… tachycardia, positive inotrope,
RAAS… NA/water retention to increase circulating volume, vasoconstriction

Question 7

what is a possible consequence of increased sympathetic drive during MDVD?

Answer 7

increased HR/contractility increases the oxygen demand, which often can’t be met leading to cell death and further decreased systolic function

Question 8

what is a possible consequence of RAAS activation in MDVD?

Answer 8

increased circulating volume leading to increased hydrostatic pressures which can cause congestion

Question 9

how is MDVD staged?

Answer 9

A - at risk
B1 - murmur and no enlargement
B2 - murmur and enlargement
C1 - CHF hospitalised
C2 - CHF at home
D1 - refractory hospitalised
D2 - refractory at home

Question 10

what murmur is heard with MDVD?

Answer 10

loud harsh left apical systolic murmur

Question 11

what does the severity of the heart murmur associated with MDVD depend on?

Answer 11

severity of mitral regurgitation

Question 12

what are some findings on physical examination consistent with MDVD?

Answer 12

tachypnoea/dyspnoea (CHF)
crackles on lungs (pulmonary oedema)
harsh left apical systolic murmur

Question 13

why is hypertension an issue with MDVD cases?

Answer 13

increases the severity of mitral regurgitation

Question 14

what is a marker of wall stretch?

Answer 14

NT-proBNP

Question 15

how can blood pressure be used as a good diagnostic tool for MMVD?

Answer 15

hypertension means there is an increased regurgitant fraction (bad prognostic factor)
hypotension will occur if the patient is in forward heart failure

Question 16

what is troponin I a marker for?

Answer 16

myocardial damage (good prognostic indicator)

Question 17

can a patient with sinus arrhythmia be in CHF?

Answer 17

no (sinus arrhythmia is due to parasympathetic tone whereas in CHF your sympathetic tone increases)

Question 18

what changes are seen on echocardiography of MDVD?

Answer 18

thickened/prolapsed leaflets
mitral regurgitation (doppler)
LA/LV enlargement
hyperdynamic systolic function

Question 19

what radiographic finding would indicate pulmonary oedema?

Answer 19

alveolar lung pattern

Question 20

what are some possible findings on ECG of a patient with MDVD?

Answer 20

can be normal
can have prolonged P wave (atrial enlargement)
can have tall R waves (ventricle enlargement)

Question 21

what treatment is indicated for MDVD in stage A?

Answer 21

none, just monitor

Question 22

what treatment is indicated for MDVD in stage B1?

Answer 22

none, just monitor

Question 23

what treatment is indicated for MDVD in stage B2?

Answer 23

pimobendan

Question 24

what treatment is indicated for MDVD in C1/2?

Answer 24

furosemide, pimobendan, ACE inhibitor, spironolactone

Question 25

what treatment is indicate for MDVD in D1/2?

Answer 25

furosemide, pimobendan, ACE inhibitor, spironolactone at higher doses with the addition of other therapies such as sequential nephron blockade

Question 26

what drugs are used to reduce preload in MDVD?

Answer 26

diuretics/venodilators (furosemide and torasemide)

Question 27

what drugs are used to reduce afterload in MDVD?

Answer 27

vasodilators…
ACE inhibitors (benazepril, enalapril)
pimobendan
sodium nitroprusside

Question 28

what drugs are used to reduce pulmonary hypertension?

Answer 28

pimobendan and sildenafil

Question 29

what are the most common group of arrhythmias seen with MDVD?

Answer 29

supraventricular (premature complexes, atrial fibrillation…)