Mitral valve disease Flashcards
(32 cards)
blood returns to left atrium via the
pulmonic vein
no valves into atria
right ventricle outflow valves into the pulmonary artery are called
pulmonic valves
Most common acquired heart disease in dogs
myxomatous mitral valve disease
(degenerative mitral valve disease)
can be a daily encounter in clinical cardiology practice
Mitral valve disease, physical exam findings:
Strong Breed predisposition (more common in small dogs! especially cavalier king charles spaniels).
Left-sided systolic murmur
Clinical consequences of mitral valve disease.
Increased preload due to mitral regurgitation during systole.
Reduced cardiac output due to blood backtracking via mitral valve.
Remember CO = SV * HR
Compensatory mechanisms in mitral valve disease in order of presentation. (4)
- Reduction of parasympathetic tone (sinus arrhythmia in dogs would disappear)
- Increase in sympathetic tone
- Water retention (RAAS)
- Cardiac remodelling
Compensatory reduction of parasympathetic tone can be seen as
the disappearance of sinus arrhythmia in dogs.
Purpose of staging heart disease. (3)
- To provide a standardized way to assess the severity
- To understand the progression
- To guide treatment decisions
Heart disease staging is based on: (3)
- Presence or absence of clinical signs
- Severity of murmur
- Diagnostic test results
ACVIM
American College of Veterinary Internal Medicine
ACVIM staging of MMVD
A-D
A = predisposition (no changes, no mumur. these indiv.s are healthy with a strong genetic predisposition.)
B = murmur or other changes present
- B substages:
B1 = no cardiac remodelling
B2 = cardiac remodelling
C = clinical sign of disease, congestive heart failure
D = no response to standard treatment
Differentiation of stages B1 and B2 of MMVD.
B = murmur or other changes present
* B1 = no cardiac remodelling
* B2 = cardiac remodelling
Auscultation: murmur grade III-VI
X-ray (look for cardiac remodelling)
* VHS > 10.5
* VLAS > 3
Echocardiography
* LA/Ao equal to or more than 1.6
* (LVIDDN) equal to or more than 1.7
What is the VLAS score?
Vertebral left atrial score.
VLAS is defined as the length of the line expressed in vertebral-body units. If the measurement is greater than 2.5, the dog probably has an enlarged left atrium/ventricle.
If the VLAS is greater than 3.0 vertebrae, the likelihood of left atrial/left ventricular enlargement is even higher.
Explain LA/Ao.
LA/Ao refers to the left atrium to aorta ratio. It is a key echocardiographic measurement used to assess left atrial enlargement, which is an important indicator of the severity of MMVD and the risk of congestive heart failure (CHF).
- Normal LA/Ao: Typically ≤ 1.5 in healthy dogs.
- Mild Enlargement: 1.5 - 1.7
- Moderate Enlargement: 1.7 - 2.0
- Severe Enlargement: > 2.0, indicating significant left atrial dilation and a higher risk of CHF.
U/S from the right hemithorax!
Explin LVIDDN.
LVIDDN stands for normalized left ventricular internal diameter in diastole. tells us about left ventricular size in diastole.
- If LVIDDN ≥ 1.7, it indicates left ventricular dilation, suggesting significant volume overload due to mitral regurgitation.
- This is a marker of cardiac remodeling and disease progression.
- A value ≥ 1.7 is often used to determine when to start pimobendan to slow heart enlargement and delay congestive heart failure (CHF).
U/S from the right hemithorax!
Tx of MMVD in B2. (6)
- Pimobendan 0.25-0.3 mg/kg BID
- Diet:
– Moderate sodium restriction
– High palatability - ACEI-s?
– Theoretical effect (RAAS blocking)
– Limited scientific evidence though. - Spironolactone?
– Theoretical benefit (aldosterone inhibition)
– Limited scientific evidence though. - betablockers block sympathetic stimulation. used widely in human med. the problem with these is they are neg. inotropic so risk of heart failure if given to the wrong type of patient. not so popular in dogs.
- surgical options make the left atrioventricular flow thorugh tract more narrow. very high risk, expensive and limited availability in vet med (UK, Munich, Austria).
No tx in stage B1 of MMVD. B = murmur or other changes present, B1 = no cardiac remodelling. B2 = cardiac remodelling
cardalis active ingredients?
when is this used?
cardalis: benazepril + spironolactone
used in more advanced cases of MMVD.
Monitoring of MMVD in stage B2. (2)
- Owner should monitor Resting/sleeping respiratory rate
– Smartphone apps available
– Be told How to react if RR increased - Re-examination
– Radiographs every 6 months
– Echocardiography every 6-12 months
– Consider NT-proBNP testing and following.
No tx in stage B1 of MMVD. Stage B = murmur or other changes present, B1 = no cardiac remodelling. B2 = cardiac remodelling
How best to discern when MMVD goes from Stage B2- Stage C, so cardiac remodelling present to beginning of congestive heart failure.
Resting RR is actually quite a sensitive tool that can be utilized by owners at home.
Diagnostic workup in stage C. (4)
Stage 3 of MMVD = congestive heart failure stage.
Resting/sleeping respiratory rate
Physical examination
– Absence of respiratory sinus arrhythmia
– Tachycardia
– Arrhythmias maybe
– Abnormal lung sounds
Radiography
– Dilation of the left atrium
– Dilation of the pulmonary vein
– Interstitial (alveolar) lung pattern
Blood tests
– NT-proBNP
– Hematology, serum biochemistry
– Urea, Crea, Electrolytes
If youre not sure if you have CHF on an xray, do what?
start diuretics at a low dose and redo thorax xray in a couple days.
Tx of acute stage C (congestive heart failure) MMVD. (5)
Diuretics
– Loop diuretics (furosemide, torasemide)
* Dose depends on severity of clinical signs
* Monitor response (RR, Xray)
* Adjust dosage
* Monitor renal parameters
* Allow access to water!
– Sequential nephron blockade with Thiazides.
Do sequential blockage if furo or tora is not enough alone.
Pimobendan 0.25-0.3 mg/kg BID
Oxygen supplementation
Anxiolytics
* Butorphanol 0.2-0.3 mg/kg
ACE-inhibitors?
Pimobendan dose and frequency
Pimobendan 0.25-0.3 mg/kg BID
Tx of chronic stage C (congestive heart failure) MMVD. (4)
Diuretics
– Adjustment of dose
– Home monitoring
Pimobendan 0.25-0.3 mg/kg BID
ACE-inhibitors
Spironolactone (aldosterone inhibitor)
Dietary management
– Sodium restriction, palatability
Re-assessment in 3-6 months
– Renal parameters, electrolytes
– Radiographs
