Cardiac Murmurs in Horses Flashcards
What history clues may indicate cardiac dx?
- Poor performance/exercise intolerance
- Lethargy/weakness
- Stunted growth (foal) or weight loss (adult)
- Persistent tachycardia of unknown origin
- Dyspnea
- Cough
- Epistaxis
- Collapse
What predisp with age and breed ?
- Atrioventricular valve regurgitation: often seen in large performance horses
- Ventricular septal defect: frequently seen in Section A Welsh ponies
- Aortic regurgitation: clinically more relevant in young horses
step 1 of CE?
OBSERVE from DISTANCE
* Mentation
* Body condition score
* Jugular distension or pulsation
* Peripheral oedema
* Breathing pattern
respiratory disease vs. congestive heart failure
Step 2 - CV specific ce?
- MM colour & CRT
- Peripheral pulse quality
What does pulse quality tell you?
- Check rhythm, rate, and pulse quality
- Indirect assessment of pulse pressure
- Bounding pulse could be aortic regurgitation
- Weak pulse pressure: low output heart failure
- Facial a., transverse facial a., dorsal metatarsal a.
Pulse pressure = ?
Systolic pressure. diastolic pressure
Does auscultation work?
- Auscultation excellent at identifying the correct valve if one regurgitation present and very good with more
- Unable to detect compartment size variation
- Murmur grade only consistent when very quiet
New technology for examination?
Acoustic Cardiography device (audiocor) -> unable to detect heart murmurs
What are the 4 sounds in horse?
- S1 = ‘LUB’, closure of AV (mitral, tricuspid) valves
- S2 = ‘DUB’, closure of semilunar (aortic, pulmonic) valves
- S3 = ventricular filling in early diastole
- S4 = atrial contraction in late diastole
What can muffled heart sounds be due to?
- Pericarditis
- Space-occupying mass in the mediastinum
- Lung pathology
what diagnostics when for heart dx?
- Radiography -> best in foals
- Echocardiogram -> non invasive - best modality for valvular structure, prolapse , regurg, chamber size
When is an echo indicated?
o New, loud murmur
o Impaired athletic performance after musculoskeletal and respiratory disease are excluded
o To rule in/out CHF
o Fever of unknown origin
When is an ECG indicated?
o To evaluate heart rate and rhythm
o Category B distribution pattern of Purkinje fibers in the ventricles
* Not sensitive to monitor chamber enlargement
What different types of ECG?
- Resting ECG
- 24hr Holter
- Exercise ECG
What lab parameters might we look at for heart dx?
- Haematology -> inflammatory/infectious? -> endocarditis or bacterial pericarditis
- Biochem -> electrolytes, liver/kidney
- Arterial blood gas: oxygenation, shunts
- Cardiac Troponin I : eval of myocardial damage
Use of blood pressure monitoring?
Can be useful
- CO
- Horses of cardioactive drugs
- Critical care monitoring
How do we do indirect BP measurement?
- Coccygeal artery
- MEtatarsal artery in foals
Direct BP cath?
requires arterial cath
What are all the features of a cardiac murmur?
- Side (Left vs Right)
- Timing (systolic vs diastolic)
- Point of maximal intensity (PMI)
- Grade
- Radiation
- Character/shape
- Mucous membranes, jugular refill, CRT
How to identify Timing? systolic vs diastolic vs continuous) ?
What does the point of maximal intensity tell you?
How do we grade murmurs?
What does character/ shape describe?
Soft vs sharp (stenosis)
Musical vs squeak
Crescendo decrescendo
How do we categorise ‘types’ of murmurs?
What is the character of a physiologic murmur?
- Soft, high frequency, low intensity, crescendo-decrescendo
- Localised: PMI pulmonic/aortic valve (heart base)
- Low grade: I-II/VI at rest, III/VI with sympathetic stimulation
Describe physiological murmurs further
o Physiologic murmur reduce at rest
o Common in young/athletic horses
o No investigation or treatment is necessary
o Filling murmur
What are the different types of pathologic murmurs?
Differentials for different types of murmurs?
WHEN TO ECHO?
1) A previously diagnosed murmur that is worsening
2) Grade 3-6/6 LHS
3) Grade 3-6/6 RHS
4) Suspected VSD or other congenital heart lesion
5) Continuous murmur
6) Clinically important arrhythmia
7) Myocardial injury
8) Suspicion of CHF
9) Concerns at a Pre purchase examination
What main causes of systolic murmur in horse?
- Mitral regrug
- Ruptured chordae tendinae
- Tricuspid regurg
- VSD
What main Diastolic murmurs?
-> Aortic regurg
Describe Mitral Regurg murmur?
o Second most common murmur in horses
o Systolic murmur with PMI mitral area (heart apex)
o Grade 1-6/6, early, mid, holo-, pan-systolic
o Common finding in any performing horses
Prognosis for mitral regurg murmur?
o Mild regurgitation may have a favourable outcome
o If young concerning
o Difficult to predict
Potential causes. of mitral regurg?
o Degenerative valvular disease*
o Mitral valve prolapse
o Ruptured chordae tendineae
o Endocarditis
o Dilated cardiomyopathy: 2º to valve annulus, ventricular dilatation (severe AR), etc.
o Mitral valve dysplasia
Clincial signs of mitral regurg?
o Mild
* Normal performance and life expectancy
o Moderate to severe
* Left atrial dilation, dysfunction, pulmonary hypertension, CHF
o LA enlargement increases the risk for AF and dangerous arrhythmia
o Left sided CHF: coughing, dyspnoea, exercise intolerance, collapse, death
Describe ruptured chordae tendinae murmur
- inflamamtory/ degen changes in chordae
- Widely radiating pansystolic murmur
- Results in marked prolpase of MV leaflets + severe regurg
What pathophysiology of ruptured chordae?
o Severe mitral insufficiency → increased LA pressure → fulminant
pulmonary oedema → acute
dyspnea, imminent death
Pg of rupture chordae?
Grave
Diagnosis of ruptured chordae?
EchoC with flail leaflet of the valve
What is usually our tricuspid regurg murmur?
holosystolic murmur with PMi right AV valve
Who do we see Tricuspid regurg in?
More common in thoroughbreds and standardbreds (inc prevalence with age and levels of training)
Aetiology of tricuspid regurg?
degen valvular dx, chordae tendinae rupture, valvulae prolapse etc
CLs & when to investigate tricuspid regurg?
CLs - >usually none;
Investigate is >3/6 grade
Prognosis for tricuspid regurg?
- Negative indicators include:
a) Structural valvular lesions
b) Signs of CHF - Regularly seen in high end training horses
Describe VSD
o Most commonly seen in Welsh Mountain ponies, Arabians, Standardbreds, Warmbloods
o +/- part of complex congenital cardiac defect (e.g. Tetralogy of Fallot)
What kind of murmur do we get with VSD?
Harsh, holosytolic murmur PMI rightside
o Small defect → higher flow resistance → loud murmur
Clinical signs of VSD?
Clinicalsigns: depends on location and size of the defect
o Usually none
o If defect is large: poor performance, poor growth, signs of various CHF
when to investigate VSD?
o Horses with clinical signs: mild to severe
o Pre-purchase exam: client expectation, young rider
o Avoid breeding
Prognosis for VSD?
o Favorable if VSD size < 2.5 cm (TB, Standardbred)
o Favorable if < 1/3 of size of the aorta size (other breeds)
o Favourable if maximum shunt velocity >4.5m/s
o Size of cardiac chambers
o Presence of Mitral or tricuspid regurgitation
o Congestive heart failure
Describe aortic regurg murmur?
- Holodiastolic murmur with PMi left heart base
- Msot frequent degenerative valvular dx in horses
- Most common in elderly horses ( if mild no stress)
Clinical signs of Aortic regurg?
o Mild case: no clinical abnormality
o Moderate to severe cases: signs of CHF
* Bounding peripheral pulses
* Poor performance, tachypnoea, weight loss, etc
risk of arrythmias?
o AR may result in atrial fibrillation and/or ventricular arrhythmia
o Not recommended to use as a lesson or high performance due to risk of SCD
When to investigate Aortic regurg?
o Murmur grade ≥ 3/6
o Bounding peripheral pulses
o If present in young horses < 10 y
o Older horses still in work
o Concurrent arrhythmia
o If showing signs of CHF
Prognosis with aortic regrug?
o If present at <10yrs old, it will likely affect work
o SCD occurs due to ventricular arrythmia
o Repeat examinations can give a better guide to prognosis
o Severe AR should only be ridden by a consenting adult
o If LA enlargement has occurred prognosis guarded
o Complete examination should include pulse wave Doppler, colour flow and
continuous wave Doppler. In some institutes clinicians are now using speckle
tracking and tissue Doppler.
What general approach for clinically insignificant murmurs?
o Physiologic murmurs
o Low grade murmur with no signs of clinical abnormality-> Prognosis for survival is usually good
o Most valvular diseases do not affect performance but has a potential to deteriorate over time
o Athletic horses may have mild regurgitation due to eccentric cardiac hypertrophy which has no
impact on performance
What is our approach with clinically significant mrumurs?
o Loud murmurs in young horses
o Progressive murmurs with mild clinical signs
o Showing clinical signs of CHF
o Prognosis should be estimated based on further evaluation results
What does Medical maangement of heart dx involve?
-> Mostly for CHF: diuretics, vasodilators, pos inotropes, care, ACE inihibtors
- endocarditis-> ABs & NSAIDs
How should we monitor horses with murmurs
- Regular PE & Auscultation -> educate slient for signs of CHF
- Repeat echo for early signs of structure changes
- advice to client: adjust horse’s activity & ridder safety
