Mitral Valve disease

Question 1

Outline what MMVD is

Answer 1

Can be considered age related change, occurs too early in Cavvies
Inherited (not simple) in CKCS and dachshunds
All heart valves may be affected
Degeneration of the vavlve leads to LA and LV overload, LV dilation and eccentric hypertrophy
Normally LV systolic function remains OK or is hyperdynamic - although can get systolic issues in large dogs
As LHS pressures increase, get L CHF

Question 2

What type of murmur do you get in MMVD?

Answer 2

Left apical early (proto-)systolic
becoming holo-or pan-systolic, “plateau” shaped
heart murmur.
Can be musical

Question 3

What do pan and holosystolic mean?

Answer 3

Pan - over both heart sounds

Holo - in between 1st and second heart sounds

Question 4

What does a cough mean in MMVD?

Answer 4

NOT CHF
LA enlargement
Possible concurrent airway dz

Question 5

What do you see in CHF in dogs with MMVD?

Answer 5

Increase RR and dyspnoea - therefore get a baseline so you now when things are increasing

Question 6

What does a wheezy cough suggest?

Answer 6

Concurrent bronchomalacia

Question 7

What do diastolic gallops suggest?

Answer 7

Heart disease (not common though)

Question 8

What Ix can you do for dogs with expected MMVD?

Answer 8

Echo
Rads
Bloods (assess for other dz and prior to diuresis)
Biomarkers
BP (systemic hypertension increases progression of disease)

Question 9

What do Pro BNP values over 1500 and 1800 suggest?

Answer 9

1500 - Increased risk CHF over next 12 months

1800 - consistent with CHF

Question 10

How do you asses for MV prolapse on echo?

Answer 10

Draw a line across the anulus - if the MV projects across you have prolapse

Question 11

What are the signs of LA enlargement echo?

Answer 11

Right parasternal 4 chamber view - bowing of intercranial septum to the R
Right parasternal short axis view (mercedes benz signs) - LA:Ao ratio should be less than 1.6

Question 12

What types of arrhythmias can occur with MVD?

Answer 12

supraventricular premature complexes
Atrial fibrillation (more large breeds)

Question 13

What is the normal CKCS VHS less than?

Answer 13

11.7 (normal is 10.7)

Question 14

What is the cornnell formula?

Answer 14

Allows scaling of M-mode measurements to understand what is normal based on dog’s body weight

Question 15

What are the requirements to be in B2?

Answer 15

Murmur 3/6 or greater
No c/s apart from mild cough
LA dilation
LV dilation in diastole >1.7
VHS >10.5

Question 16

What did the Epic study show?

Answer 16

Giving pimobendan to stage B2 patients increases symptomatic period by 15m

Question 17

What is the ideal immediate acute CHF treatment?

Answer 17

IV frusemide 1-2mg/kg initally, then 1mg/kg every 1-2 hours until RR < 55
May involve giving dose totally >20mg/kg/day
Monitor urea and crea initially and after 24 hours

Question 18

What can be an issue with frusemide boluses?

Answer 18

Can lead to rebound RAAS activation

Some will use CRIs although these may have a higher risk of azotaemia and dehydration

Question 19

How and when can you start frusemide as an outpatient treatment?

Answer 19

Oral start if not dyspnoic
Monitor renal function after 7d
Count RRR at home to titrate

Question 20

Why should you not use frusemide on its own?

Answer 20

Leads to RAAS activation

Question 21

What are the bad effects of congestive heart failure due to sympathetic stimuation and RAAS activation?

Answer 21

Vasoconstriction
Increased HR
Myocardial remodelling/ fibrosis
Oedema/ effusions

Question 22

Why is Angiotensin II the main bad guy with CHF?

Answer 22

Leads to remodelling, Na and H20 retention and vasopressin release

Question 23

What is the use of ACEi in CHF?

Answer 23

Leads to improved survival, QoL, haemodynamic parameters

Question 24

When should ACEi be avoided in CHF patients?

Answer 24

Patients with low BP needing high doses of frusemide

Is for chronic use, not needed when dealing with acute episode

Question 25

Outline pimobendan

Answer 25

Is a Ca sensitiser - +ve inotrope
Is a phosphodiesterase inhibitor - +ve inotrope and vasodilator
Main benefit in MMVD = arteriodilation, Increase in forward stroke volume and decrease in regurgitant stroke volume
Reduces LA pressure and cardiac size

Question 26

Outline the use of spironolactone

Answer 26

Aldosterone antagonist
K+ sparing diuretic
Counteracts remodelling

Question 27

Should quadruple therapy be used for CHF?

Answer 27

Logic suggests yes but no concrete evidence for it

Question 28

What should you do in stage D patients?

Answer 28

Ensure optimum dose of pimobendan and other drugs
Some will suggest TID pimobendan
BID ACEi
If RCHF and gut oedema, give parenteral drugs
Ensure giving spironolactone as reduces risk of frusemide resistance
Consider changing to torasemide
Consider sequential nephron blockage - hydrochlorothiazide/ amiloride
Consider further afterload reduction with amlodipine/ similar if BP OK
identify and tx arrhythmias
identify and tx pulmonary hypertension

Question 29

When is increasing frusemide unlikely to be effective

Answer 29

Once passed 3mg/kg TID

Question 30

Outline the use of torasemide

Answer 30

Approx 20x as potent as frusemide so when changing cut the frusemide dose by 20
V high risk AKI - monitor renal values and lytes 2d and 7d post use and any change in dose

Question 31

Outline pulmonary hypertension

Answer 31

May have loud tricuspid regurge murmur
Likely to have exercise intolerance/ collapse on exertion
May be d/t increased LA pressure, which is transmitted across the pulmonary vasculature to result in pulmonary arterial hypertension
Pulmonary artery systolic pressure can be estimated from the tricuspid regurge velocity in the absence of pulmonary stenosis

Question 32

How do you treat ruptured chordae tendinae

Answer 32

If minor - may only see mild increase in CHF
Tx wih vigorous afterload reduction
If a primary cord is ruptured, is likely to be a terminal event

Question 33

What occurs in a LA tear?

Answer 33

Pericardial h+
Cardiac tamponade
Diastolic collapse of RA

Question 34

When would you suspect a LA tear?

Answer 34

Presents collapsed, hypotensive,
muffled heart sounds, quieter heart murmur
See pericardial effusion with large LA on scan

Question 35

How do you treat a LA tear?

Answer 35

Give drugs to reduced LA pressure - nitroprusside, amlodipine, hydralazine
If needed, support preload with cautious use of fluids
Increase frusemide dose
Avoid pericardiocentesis
If can get over the first week, can do well

Question 36

What is the MST once the pet is in heart failure?

Answer 36

Less than a year

Question 37

What are good/ bad prognostic indicators for MST once in CHF?

Answer 37

Good - being a CKCS, higher creatinine, lower frusemide dose needed
Bad - exercise intolerance, larger VHS, greater LA:Ao ratio