Equine Cardiac Murmurs Flashcards
What are 2 types of endocardial disease?
Endocardiosis
Endocarditis
What is endocardiosis?
Valvular degeneration - progressive
Mitral, aortic or tricuspid valves
What is endocarditis?
What can it cause it cattle and equine?
- Bacterial in origin secondary to bacteraemia
- uncommon but is important in all species
- Cattle: Liver abscess, TRP, mastitis
- Equine: Dental, respiratory, thrombophlebitis
- Other causes
- Valve dysplasia
- Valvulitis
- Valve prolapse
- Ruptured chordae tendinae
What are clinical signs of bacterial endocarditis?
- Acute onset Congestive heart failure
- Fever, cardiac murmur, tachycardia, tachypnoea
What do you see on laboratory data with bacterial endocarditis?
- Hyperfibrinogenaemia, anaemia and leucocytosis
- Blood culture
- Repeat x3 (false negatives) ideally when pyrexic
- Sterile procedure (do not use indwelling catheter)
What are some common differentials for a systolic murmur on the LEFT hand side?
- Between S1 and S2 if in systole
- Mitral loudest just behind tripces
- Further forwards underneath triceps – aortic flow, potentially pulmonic
- Most flow murmurs are related to LHS ejection, just because pressures higher
- Cannot differentiate aortic from pulmonic just from stethoscope
- There will be horses with both – flow murmurs and regurgitation
If you have a murmur IN SYSTOLE, when would you hear it?
Between S1 and S2
Where would a mitral valve be loudest?
LHS
Just behind triceps
Where would aortic flow murmur be heard loudest?
Can you tell this from a pulmonic flow murmur?
- Further forwards underneath triceps – aortic flow, potentially pulmonic
- Cannot differentiate aortic from pulmonic just from stethoscope
12 year old polo pony, Male, 470kg
Presents with a recent onset depression and poor performance.
The following is audible on the left side over the 5th intercostal space
- What is a likely diagnosis based on where it can be heard?
- Could the murmur you pick caused the clinical signs?
As its in the 5th intercostal space. 12 year old horse, MR – its very common! Most likely to result in clinical signs, not because they go into CHF, but because it causes LA enlargement and predisposes them to atrial fibrillation
What is the second most common form of valvular heart disease?
Mitral insufficiency
What iis the most common cause of clinical signs of cardiac disease?
Mitral insufficiency
Mitral insufficiency:
- What grades can it be?
- When will you hear it?
- What is its shape?
- Where is it loudest?
- How does it radiate?
- Grade: 1 – 6 /6
- Timing: Early, mid, holo, pan- systolic
- Shape: Band Shaped (if its deep crochendo, it gets quieter)
- Loudest: Left 5th intercostal space
- Radiates: Caudodorsally
- Move stethoscope in different areas to find where you can heart it
- MR- will go from apex to base, so this is the area that the jet will radiate
What can be some clinical signs of mitral insufficiency?
- Incidental finding
- Finding murmur on routine exam that is causing the horse no problems at all, not usually a problem
- Poor Performance
- Only because predisposes them to LA enlargement which they can then get atrial fibrillation
- Atrial fibrillation
- left-sided failure (Acute onset)
- If acute onset Mitral valve disease e.g. caused by bacterial endocarditis – will go rapidly into LHS heart failure
- Right-sided failure – although uncommon, its more likely we will see this as we don’t really see LHS failure from the outside
- If progresses over months to years, this is the thing we will recognise
- Peripheral oedema, jugular pulsation (if LHS failure – pulmonary oedema) – can see the RHS things more than the LHS things
Collapse, fainting or sudden death
How does mitral insufficiency progress?
Mitral Regurgitation
- regurgitant jet, more blood from LV to LA during ventricular systole, although slight reduction in CO – rarely cases clinical signs. Get LA enlargement as a result, so during diastole, more blood in atria, so therefore LV gets enlarged as well – and the 3rd heart sound will become a lot louder. If MR plus a loud 3rd heart sound – POOR PROGNOSIS
- Diastole - Increased ventricular filling. Loud third heart sound
- Systole - Increased ventricular work will increase the regurgitant fraction. Left Atrial enlargement > AF
- More blood in LA in systole than normally, get back flow through blood through into lungs so get pulmonary artery hypertension –> increased pressure on vascular pulmonary arteries, this is the weak point in horses CVS – this is the point that can rupture
If pulmonary arteries are enlarged, what should happen to the horse?
If pulmonary arteries enlarged, horse should retire as a number of them can rupture pulmonary artery at exercise, collapse and die
If pulmonary artery is bigger than aorta, what should you suggest for the horse?
If PA bigger than aorta, has hypertension, recommend this horse stops work
What are these 3 arrows pointing to on this echo?
What should happen to this horse?
This horse have severe MR
Top arrow - right artrium
Middle - aorta
Bottom - pulmonary artery
If PA bigger than aorta, has hypertension, recommend this horse stops work – they didn’t listen, horse died 6 months later
What are some indications for echocardiography in a horse with mitral regurgitation?
- Grade > 3/6
- Grade 3 or above – should undergo further examination
- Loud third heart sound
- Already know will have a big LA – should either undergo further exam or say do not ride this animal
- Resting tachycardia
- Suggests may have heart failure
- Fever
- Acute onset and related to fever – might be bacterial endocarditis
- Poor performance
- Arrhythmias
What is a physiological flow murmur?
Innocent heart murmurs are harmless sounds made by the blood circulating normally through the heart’s chambers and valves or through blood vessels near the heart
- Where are left sided physiological murmurs loudest?
- What is their intensity?
- When is their usualy timings?
- Where do they radiate?
- What is their shape?
- Loudest over left 4th intercostal space (cranially) – usually less than a grade 3, usually 1 or 2
- Intensity - Usually < 3
- Timing - Usually early to mid systolic
- Radiation - Cranio-dorsal
- They don’t radiate very much and usually very localised
- Shape - Crescendo decrescendo / Decrescendo
What are some common differentials for a RIGHT systolic murmurs?
Tricuspid insufficiency
Ventricular septal defect
Tricuspid insufficiency
Which breed is it most common in?
Thoroughbreds and standardbreds
Tricuspid insufficiency
- What grade is it most commonly?
- When is its timing during the heart sounds?
- What is its shape?
- Where do we hear it loudest?
- Where does it radiate?
- Grade : 1 - 6/6 – can go up to any grade, tend to be lower usually
- Timing: Holo or pansystolic
- Shape: Crescendo-decrescendo or Band-shaped
- Loudest: Right 4th intercostal space
- Radiates: Craniodorsally – dorsla part is the important part here
What can tricuspid be related to in thoroughbreds?
How well tolerated is it - how much does it progress?
- May be related to hypertrophy (likely due to training)
- Generally well tolerated in TB
- Uncommon to see progression of this disease
- Exception is bacterial endocarditis
What are some scenarios where you would investigate a tricuspid insufficiency further?
- Grade > 4/6 in racehorses
- Grade > 3/6 in other types, especially ponies so you definitely know it is tricuspid regurgitation
- Right sided heart failure
- Jugular pulsation and distension
- Ventral and peripheral oedema
- Poor performance
- Atrial fibrillation
- Related to septic jugular thrombosis
What breeds is ventricular septal defects most common in?
Common in welsh ponies
Where would you hear a ventricular septal defects?
- Concurrent systolic murmur on LHS (LIC4)
- Usually due to relative pulmonic stenosis
What can a ventricula septal defect go on to cause?
VSD can go onto to LV enlargement, but depends on size of them
What are some differentials for diastolic murmurs?
Ventricular filling murmur
Aortic insufficiency - Can technically get pulmonary insufficiency, but they are very rare and we don’t know much about them at the moment
What is the most common form of equine valvular heart disease in the OLDER horse?
Aortic insufficiency
Does aortic insufficiency progress? If so, what to?
- Its progression – can go on to develop cardiac enlargement and can go on to cause ventricular dysrhythmias.
- Mitral regurgitation can cause atrial fib
- Aortic insufficiency – ventricular enlargement – ventricular tachycardia
Aortic insufficiency
- What grade can it be?
- When is its timing?
- What is its shape?
- Where is it loudest?
- Where does it radiate?
- Grade: 1-6/6
- Timing: Early or holo DIASTOLIC
- Shape: Decrescendo
- Loudest: Left 4th intercostal space
- Often audible on right hand side
- Radiates: Caudoventrally
When can bounding (hyperkinetic) pulses be heard?
What can cause them?
- Can hear on both sides as aorta sits in middle of heart so jet can go to LHS or RHS depending on defect
- Horses with aortic regurgitation – can go on to develop bounding pulses and the reason for this:
- Horses with AR – because of leaking aortic valve, get backflow of blood which causes LV enlargement and then because of this – LV more dilate, more blood during next cardiac cycle, systolic pressure will increase – but other thing that happens is that because of leaking valve, unable to maintain diastolic pressure during diastole, so diastolic pressures drop off – so increase systolic pressure and decrease diastolic pressure – and if they have these with bounding pulses – will have a big LV
With aortic insuffiency, you can get bounding pulses and dilated LV - what can this then lead to?
With progression left ventricles dilates, mitral valve annulus becomes incompetent and develop mitral insufficiency murmur
Is aortic insufficiency a risk for exercise and riding the horse?
If its progresses enough!
- Considered a risk for exercise induced ventricular tachycardia
- Collapse and death
- Can get V tach at exercise – when it has someone on its back, might get ventricular tachycardia or fibrillation and may collapse and die!
- If ANY VPC’s seen – assume they may go on to develop a more pathological ryhtm and therefore could be dangerous to ride
In horses with aortic insufficiency, what is there a higher prevalence of on ECG?
What can it be caused by?
- There is a higher prevalence of ventricular arrhythmias in horses with aortic insufficiency compared with other forms of valvular insufficiency
- Incidental finding
- Concurrent myocardial and endocardial pathology
- Catecholamine-induced?
- Altered coronary artery blood flow?
What are some situations that would warrant further investigations in horses wih aortic insufficiency?
- Hyperkinetic pulses
- Murmur grade > 3/6
- Young horse
- Unusual so might be thinking about bacterial endocarditis
- Old horse still in work
- Concurrent murmurs or arrhythmias
- Poor performance
- Fever
- Congestive heart failure
- Might want to echo or say enough is enough
What can you use echocardiography to assess with aortic insufficiency?
- Left ventricular enlargement or other secondary changes such as:
- Mitral valve regurgitation
- Jet size
How common is pulmonic insufficiency in the horse?
Can it affect performance?
- PI is uncommon in the horse
- When it occurs it rarely affects performance
- A common echocardiographic finding
- Doppler echocardiography
What is cor pulmonare?
abnormal enlargement of the right side of the heart as a result of disease of the lungs or the pulmonary blood vessels
- Cor pulmonale
- Right ventricular hypertrophy
- Pulmonary Hypertensin
- Alveolar hypoxia
- Marked dyspnoea
- PA enlargement and PI
What can cause a continuous cardiac murmur?
- Aortic root rupture – dissecting lesion, ruptured aorta, recognised condition esp stallions and Friesians, collagen defect making more likely to happen. Loud continuous murmur
- Aorto-cardiac fistula
What is a Continuous cardiac murmur usually accompanied with?
- Continuous loud cardiac murmur
- Grade 4-6/6
- Often accompanied by ventricular tachycardia (>100bpm)
- Disruption to interventricular conduction tissue
What is the prognosis for a Continuous cardiac murmurs?
- Usually fatal
- Acute cardiac failure
- Collapse
- Exsanguination
Name some causes of Cardiac Murmurs that are well-tolerated?
- Physiological murmurs
- Tricuspid and many mitral insufficiencies in athletes, provided that there are no structural valvular lesions
- Slowly progressive aortic insufficiency in middle-aged horses
What are some causes of cardiac murmurs that are poorly-tolerated?
- Acute onset lesions such as
- ruptured chorda tendinea,
- bacterial endocarditis
- valvular insufficiency associated with myocardial pathology
- Valvular insufficiencies with concurrent arrhythmias
- Progressive lesions
With a physiological flow murmur:
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Systolic PMI LIC4 (or diastolic)
- No issues
Mitral regurgitation
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Marker of severity?
- Systolic PMI LIC5
- Atrial fibrillation
PA dilation (rup) - Loud S3
Echo
Tricuspid regurgitation
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Marker of severity?
- Systolic PMI RIC4 radiating dorsally
- Rare
Atrial fibrillation - Loud S3
Echo
Ventricular septal defect
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Marker of severity?
- Systolic RIC4 radiating ventrally. Also LIC4 (PS)
- CHF if severe
- Echo
Aortic regurgitation
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Marker of severity?
- Diastolic
- Dysrrhthmias
- Hyperkinetic pulse, ECG, Echo
Ruptured aortic root
- Where is the murmur, where/when do you hear it?
- What issues does it cause?
- Marker of severity?
Continuous
- Severe
- Poor px
