Small animal congenital cardiology + mitral valve + endocarditis Flashcards
What is the only continuous murmur and wht does it sound like
- PDA
Louder in systole but present throughout
What is the different in tone of valve insufficiency/regurg murmur noise vs outflow obstruction from valve stenosis
Valve regurgitation = softer sound
Valve stenosis = harsher
Characteristics of physiological murmurs in puppies
Low grade and soft <3
Disappear or change when the puppy is moved around
Listen a few weeks later and will probably be gone
Which congenital heart diseases are more common in dogs vs cats
In dogs: pulmonic stenosis, subaortic stenosis, PDA
In cats: tricuspid dysplasia, ventricular septal defect
Signalment of pulmonary stenosis
Bulldogs, boxers, GSDs, small dogs … large range
Clinical signs of pulmonary stenosis
Left sided systolic heart murmur most intense at heart base
Normal pulse quality
Can lead to right sided CHF
murmur intensity correlates with stenosis severity
What are some consequences of severe pulmonary stenosis
Exercise intolerance
Syncope/collapse
Right sided congestive heart failure
Pathogenesis of pulmonary stenosis
Pulmonary valve diameter decreased so get pressure overload in the right ventricle
Leads to right ventricular hypertrophy
What are the three types of pulmonic stenosis and which is most common
Valvular stenosis is most common
ALso subvalvular/infundibular stenosis
Supravalvular stenosis very rare
What are the three types of pulmonic stenosis and which is most common
Valvular stenosis is most common
ALso subvalvular/infundibular stenosis
Supravalvular stenosis very rare
What are the two types of valvular stenosis
Type A = where there is pulmonic leaflet thickening and fusion; see parachuting movement due to fusion at the tips
Type B = where the valves and dysplastic and fused and the pulmonary artery is too narrow; this is the more aggressive phenotype
Which breeds do we tend to see anomalous prepulmonic coronary artery in (as a cause of subvalvular stenosis)
French and English bulldogs
What is anomalous prepulmonic coronary artery
Where both coronary arteries come from one orifice so one must go around the pulmonary artery to reach the correct ventricle, thereby strangling it
= Subvalvular/infundibular cause of pulmonary stenosis
How can we grade pulmonary stenosis
Via severity of right ventricular hypertrophy
Via doppler derived pressure gradients where mild is <50mmHg, moderate is 50-80 and severe is >80mmHg
Treatment of pulmonary stenosis based on severity
Mild = no treatment
Moderate; only treat if there is another associated cardiac abnormality
Severe = needs treatment; balloon valvuloplasty first line or surgery patch graft
When might we choose surgical patch graft rather than balloon valvuloplasty for pulmonic stenosis
In severly displastic valves
If they don’t respond to balloon valvuloplasty
How does a balloon valvuloplasty work
Use a balloon to dilate the stenosis and reduce obstruction
Access heart via jugular vein, measure stenosis using contrast to choose which balloon size, inflate balloon with saline and contrast so it ruptures the adhesions between valve leaflets
Potential complications fo balloon valvuloplasty
pulmonary regurgitation/insufficiency - this is less of an issue
Arrythmias
At what stage is it better to perform a balloon valvuloplasty for pulmonic stenosis
Early on in the asymptomatic phase as better outcome then when there is right sided failure
What is a contraindication for balloon valvuloplasty for pulmonic stenosis
Anomalous coronary artery due to risk of rupture
Whehn might transpulmonary stent implantation be indicated
In cases of anomalous coronary artery to keep valve leaflets open without risking coronary artery rupture
In severe cases with unsuccessful balloon valvuloplasty or re-stenosing
What is the pathogenesis of patent ductus arteriosus
When the ductus arteriosus doesn’t close after birth, blood shunts from the aorta to the pulmonary artery (from higher to lower pressure)
So goes back around lungs
Get overloading of lungs causing congestion
Issue of volume overload
Left ventricle becomes dilated to accommodate extra blood
Then get backwards congestion to capillaries and pulmonary oedema
= L sided CHF
What is the normal ratio of width or right to left ventricle
1:3
What do chicken fat bloot clots suggest about the animal
It was anaemia (or there was prolonged agony)
In which breed is PDA an inherited trait
Poodles
Which breeds do we commonly see PDA in
Poodles
Chihuahua, mlatese pom
What is the cause of ‘nutmeg liver’
Right sided CHF where there is backing up of bressure from right atrium to caudal VC and liver
= due to centrolobar congestion causing hypoxia, degeneration and necrosis of centrolobulary hepatocytes
Which breeds most commonly have persistent foramen ovale
Boxers, Dobermans, Samoyed
Which breeds do we see ventricular septal defects in more commonly
English bulldog
English springer
WHWT
How does the heart septum form (two parts)
Septum membranosum comes from the base of the heart while septum muscularis is from the apex
Defect in the septum membranosum is more common
Which breeds do we see tetralogy of fallot in most
Keeshonds (inherited)
English bulldogs (congenital)
What are the primary and secondary defects in tetralogy of fallot
Ventricular septal defect
Pulmonic stenosis
Dextraposition of aorta
Secondary defect = hypertrophy of right ventricle
Which breeds is pulmonic valvular stenosis inherited in
Beagle, English bulldog, Chihuahua
What does the heart look like in pulmonic valvular stenosis
Valves are thickened white and less elastic
There is blood overload in the right venitrcle leading to right ventricular concentric hypertrophy
What two things could happen in subaortic valvular stenosis
Normal response is concentric hypertrophy of left ventricle
Can get dilation instead; this is worse
WHat breeds is subaortic valvular stenosis more common in
Boxer (inherited)
Newfoundland, GSD
What signs do we notice with persistent right IV aortic arch
= vascular ring over oesophagus so see megaoesophagus and regurgitation at weaning
What is the most common cardiovascular disease in dogs
Myxomatous mitral valve disease
How does MMVD work
Get progressive degenerative lesions to the mitral valve (accumulation of proteoglycans in leaflets causing thickening)
-> Leads to mitral regurgitation and secondary volume overload of the left heart i.e increase in preload
This chronic volume overload causes eccentric hypertrophy and chamber dilates
When does mitral valve disease progress to heart failure
When unable to compensate
How does MMVD lead to pulmonary oedema
Get progressive LV and LA dilation via eccentric hypertrophy
Increase in left atrial pressure
When this becomes high than the pulmonary venous pressure causes congestion and pulmonary oedema `
What are common sequelae of MMVD
**Left sided congestive heart failure i.e pulmonary oedema
**Arrhythmias esp atrial fibrillation following enlarged LA
Can see left atrial tears or septal defect
Pulmonary hypertension
What are the stages of mitral valve disease
A = predisposed i.e cavalier king charles spaniel
B = preclinical disease
> B1 means there is mitral regurgitation but no secondary remodelling
> B2 means there has been remodelling so see LA and LV dilation
C = congestive heart failure
D = refractory CHF
Which breeds are predisposed to MMVD
Mostly small breeds
Middle aged to older
Can see in large breeds where it tends to progress quicker
What do we see in history and clinical exam of stage B MMVD dogs
ASymptomatic
May have a cough/resp disease that isn’t due to heart failure i.e from enlarged atrium compressing the trachea
Left apical systolic murmur
What do we see in history of stage C CHF dog MMVD
Murmur in history
Now increased resp rate and effort
Cough
Exercise intolerance
Lethargy
Collapse/syncope.
+ may have weight loss etc
What do we see on clinical exam in MMVD dogs stage C
Murmur
Tachynoea
Dyspnoea
Tachycardia
Tachyarrhythmias
May see signs of right sided congestive heart failure too
What do we look for on a heart echo
Identify the cause of the murmur i.e assessing for mitral regurgitation
Assessing for seconadry cardiac remodelling to stage the disease
Identify any comorbidities
What measurements do we take on a cardiac echo to assess for remodelling
Left ventricular size
Left atrial size (want La:Ao <1.6)
What imaging modality is gold standard for diagnosing pulmonary oedema in stage C MMVD
Radiography because can look for concurrentr esp disease suggesting pulmonary oedema and stage C
+ can try to assess for cardiomegaly via vertebral atrial size and heart size to stage B1 vs B2
What does BNP tell us about
Stretch on the heart
But takes a long time to get results and no cut off currently to stage between B1 and B2
Treatment for stage B1 MMVD
No treatment
Recommend biannual auscultation and imaging repeated
Treatment for stage B2 MMVD
Pimobendan
+ start monitoring the resting respiratory rate and effort at home; should be below 30
Take care with fluids during GAs
How does pimobendan work
PDE III inhibitor, calcium sensitsor, positive inotrope, arterial and venous dilator
What will owners report as an animal progresses from stage B2 to C
Slowing down, coughing, resting resp rate has increased, increase in heart rate, higher murmur intesntiy
Confirm with X rays looking for pulmonary oedema
What should we do if we get unstable heart failure case to diagnose
Just avoid sedating for X rays and start treating without them
What drug do we add in to threat MMVD stage C
Furosemide diuretic
What do we see on a radiograph on stace C MMVD
Marked cardiomegaly with left atrial dilation
Diffuse bronchointerstitial lung pattern
Pulmonary oedema?
What extra drugs can we add in to treat heart failure once stable on diuretics and pimobendane
ACE inhibitors
What other possible condition must we excluse before starting diuretics if we se effusions and right sided CHF failure signs
Pericardial effusion and cardiac tamponade
with CHF we should avoid diets high in what
Sodium
What is endocarditis and what organisms are typically involved
Bacterial infection of endocardial surface of the heart; due to bacteraemia and endothelial damage allows bacteria to lodge
Key = CONCURRENT pathology creating risk factors for endocarditis
Involves staph, strep, E coli, pseudomonas, bartonella
What is the typical presentation of endocarditis
Medium to large breed dogs
New murmur typically a red blad, arrhtyhmias, CHF
What are some potential consequences of endocarditis
Thromboembolic event
Valve regurgitation
Myocarditis
Arrhtymias
Immune stimulation
Can quickly go from no regurgitation to severe regurgitation so there is a risk of sudden onset heart failrue
Diagnosis of endocarditis
No definitive test: key = try blood culture, aspectially taken 3 times for 3 different veins ~30 mins apart
- Do clinical exam
- Haem/biochem for inflammatory markers
- Echo
- ECG
- Thoracic radiographs
What is the modified Duke’s criteria for endocarditis definitive vs possible result (in terms of number of major vs minor critera)
Definitive result = 2 major critera or 1 major and two minor
Possible result = 1 major and 1 minor; or 3 minor
What are major criteria for endocarditis
Positive echo i.e vegetative lesions on valve
Positive blood culture on at least 2 cultures (or 3 if risk of skin contamination)
New valvular insufficiency
What are minor criteria for endocarditis
Fever
Medium/large breed
Subaortic stenosis
Thromboembolic disease
Immune mediated disease
positive blood culture but not meeting major criteria
High bartonella serology
Treatment for endocarditis
Antibioitics IV for a few days
Anti-thrombotics e.g clopidogrel to reduce risk of thromboembolic events
Treat the heart failure
