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Equine murmurs Flashcards

1
Q

3 broad causes of equine murmurs

A

Not associated with valve pathology
Associated with valve pathology
Congenital abnormalities

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2
Q

Examples of murmurs not associated with valve pathology - 2

A

Physiological/flow murmurs - horses

‘Functional/physiological’ valve regurgitation - horses

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3
Q

Examples - murmurs associated with valve pathology - 5

A 
Valve degeneration (endocardiosis)
Bacterial endocarditis
Valve prolapse
Ruptured chordae tendinae
Valve regurgitation 2ndary to ventricular dilation
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4
Q

Examples - murmurs associated with congenital abnormalities

A

VSD (90% congenital abnormalities)
PDA
Valvular dysplasia

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5
Q

How to assess cardiac murmurs

A

Auscultation - determine valve affected and tentative diagnosis. Select cases for further evaluation. Timing, intensity, PMI, pitch/quality/character/shape, radiation, precordial thrill

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6
Q

What are the normal heart sounds in a horse?

A

S1, S2, S3 and S4

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7
Q

Methods to further evaluate murmurs - 2

A

Echocardiography

Electrocardiography

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8
Q

What does echocardiography permit? 3

A

Confirm Dx
Assess lesion severity
Prognosis - suitability for riding

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9
Q

What does electrocardiography permit?

A

Little value in murmur assessment in horses/FA but does allow identification of concurrent arrhythmias

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10
Q

Uses of 2D and M-mode echocardiography - 4

A

Assess valve S+F (prolapse)
Assess chamber size (enlargement/volume overload)
Assess myocardium (hypertrophy)
Monitor progression

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11
Q

What are the 2 types of Doppler echocardiography?

A

Spectral and colour flow

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12
Q

What does Doppler echocardiography allow you to do?

A

semi-quantitative assessment of valvular regurgitation (measure volume and velocity of regurgitant jets)

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13
Q

Outline ‘functional/physiological’ valve regurgitation in horses

A

Mainly Tb horses in training
Mainly mitral and tricuspid valves (auscultation)
Also aortic and pulmonic (echo)
DDx from regurgitant murmurs due to pathology.

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14
Q

Outline ‘aortic flow murmurs (a type of physiological flow murmur).

A 
Early-mid systolic crescendo-decrescendo:
common
quiet (< grade 3)
local radiation only
PMI = heart base (or aortic valve)
Variable effect of exercise on murmur
Normal - especially fit horses
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15
Q

Outline BF in murmurs

A

A murmur is the non-laminar flow of blood (this creates turbulence which is heard as a murmur). Normal BF is laminar.

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16
Q

Name 2 types of physiological ‘flow’ murmurs

A

Aortic flow murmurs - more common

Ventricular (mitral and tricuspid) flow murmurs - less common

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17
Q

Outline ventricular (mitral and tricuspid) flow murmurs (a type of physiological flow murmur).

A

Early diastolic
Less common (than aortic flow murmurs)
Short duration
High pitched ‘squeak’ or ‘whoop’
After S2 but before S3 (if present)
PMI = heart base or AV valves, LHS/RHS/both
Normal - especially in young Tbs in training

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18
Q

Outline valve regurgitation in horses.

A
  • Common in normal horses at work (30%)
  • Mitral > tricuspid > aortic
  • Variable severity and significance - many are non-progressive ‘functional regurgitations’ OR associated with valve pathology (significance related to cause, may be progressive OR sudden onset, may be fatal)
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19
Q

Is valve regurgitation common in pet dogs?

A

No (common in fit horses). BUT common in fit racing greyhounds. This is because as training increases, the myocardium becomes more powerful –> increased driving pressure in the ventricles –> increased likelihood of valve leakage.

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20
Q

How do you differentiate valve regurgitation in horses that is pathological versus (non-physiological and associated with training)?

A

Echocardiography

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21
Q

Outline mitral regurgitation (MR)

A

Significance and auscultation findings vary with cause (may be quiet, ‘functional’ murmur):
- Intensity and radiation increase with severity
INTENSITY (1-6/6)
TIMING: early, mid, holo, pan-systolic
SHAPE: plateau (band) shaped
PMI: left 5th ICS (i.e. apex)
RADIATES: caudodorsally (jet direction)

If severe = risk of collapse/sudden death due to PA rupture.

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22
Q

What is the only valve that if it has regurgitation can cause sudden death in horses?

A

Mitral valve

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23
Q

Define: holo-systolic murmur

A

Valve leakage between S1 and S2

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24
Q

Define pan-systolic murmur

A

Valve leakage as soon as the valve is closed (S1 is buried)

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25
What is an early/mid/late systolic murmur?
When the valve leaks only for a part of systole.
26
Name 3 common pathological valve regurgitations - horses
Mitral Tricuspid Aortic (Pulmonic - very uncommon)
27
Why may the PA rupture in mitral regurgitation?
Due to PA back pressure and forward pressure --> PA rupture --> sudden death of the equine
28
How common are stenoses in horses?
Very rare - shouldn't be on an everyday DDx list. (this includes valve and OT stenoses)
29
Outline tricuspid regurgitation (TR) in horses
``` Significance and auscultation findings vary with cause - may be quiet 'functional' murmur. Intensity and radiation increase with severity. INTENSITY: 1-6/6 TIMING: early, mid, holo, pan-systolic SHAPE: plateau (band) shaped PMI: right 4th ICS RADIATES: craniodorsally ```
30
What is aortic regurgitation (AoR) often due to?
Endocardiosis (this cause is much more likely than for MR or TR).
31
Outline aortic regurgitation (AoR)
``` More common in older horses May initially be an incidental finding BUT usually progressive - intensity and radiation increase with severity: INTENSITY: grade 1-6 TIMING: holodiastolic (i.e. S2 to S4) SHAPE: decrescendo PMI: aortic valve (left basal area) RADIATES: caudoventrally and to RHS ```
32
When might MR be significant? 7
``` If any one of the following are present: associated with poor performance Resting tachycardia (i.e. >50bpm) Abnormal pulse quality , slow CRT signs of left-sided CHF Arrhythmias - especially AF Louder than grade 4 Wide radiationp ```
33
When might TR be significant? 7
``` If any one of the following are present: associated with poor performance Resting tachycardia (i.e. >50bpm) Abnormal pulse T signs of right-sided CHF Arrhythmias - especially AF Louder than grade 4 Wide radiation ```
34
When might AoR be significant? 6
If any one of the following are present: - poor performance - resting tachycardia - bounding ('hyperkinetic') arterial pulse (due to large systolic/diastolic pressure difference. Regurgitation into LV) - slow CRT - signs of left-sided HF - arrhythmias - especially AF
35
List some common causes of murmurs associated with valve pathology
- Degenerative valvular heart disease (endocardiosis) - commonest valve pathology - Bacterial endocarditis
36
T/F: many valve regurgitation sin horses are NOT associated with obvious valve pathology
True
37
Outline bacterial endocarditis - horses and ruminants
Occurs secondary to bacteraemia: RUMINANTS: liver abscess, traumatic reticulitis, metritis, mastitis, navel abscess, joint ill HORSES (less commonly): site of sepsis often not identified, septic jugular thrombophlebitis
38
Why is prompt treatment of bacterial endocarditis important?
Large proliferative 'vegetative' lesions may develop, limiting prospects for return to normal valve function.
39
Causative organisms - ruminants - bacterial endocarditis
Enterococci Streptococci Actinomyces pyogenes
40
Causative organisms - horses - bacterial endocarditis
Pasteurella Actinobacillus Streptococci Rhodococcus equie
41
Causative organisms - pigs - bacterial endocarditis
Staph. aureus Actinobacillus suis Erysipelothrix rhusiopathie
42
Area of ruminant heart affected in bacterial endocarditis
Tricuspid and pulmonic valves | Right ventricular endocardium
43
Area of equine heart affected in bacterial endocarditis
Mitral>aortic Can include aortic root Right-sided associated with jugular thrombophlebitis
44
Area of swine heart affected in bacterial endocarditis
Mitral, aortic (usually PM finding)
45
Diagnosis - heart murmurs associated with pathology
CS: CHF, fever, cardiac murmur, tachycardia, tachypnoea LAB: hyperfibrinogenaemia, anaemia, leucocytosis BLOOD CULTURE: repeat 3* ideally when pyrexic and remember this is a sterile procedues (don't use indwelling catheter)
46
Tx - bacterial endocarditis
BS AB based on sensitivity
47
Prognosis - bacterial endocarditis
Guarded even after bacteriological cure - permanent structural damage to vlave. In horses, some right-sided lesions may have return of performance. Septic emboli may shed to distant sites - lungs (from right heart), kidneys/joints etc (from left heart).
48
Name 2 less common causes of murmurs associated with valve pathology
Valve prolapse | Ruptured chordae tendinae
49
Outline valve prolapse
ANY VALVE - may cause audible murmur (e.g. mid-systolic crescendo-decrescendo), considered to be a physiological rather than pathological phenomenom (controversial), non-progressive regurgitation DIAGNOSIS: echo
50
Name 2 causes of sudden death in horses related to CVS
Ruptured chordae tendinae | Ruptured PA
51
When might chordae tendinae be ruptured?
Spontaneously OR secondary to inflammatory or degenerative changes in the chordae.
52
Outline chordae tendinae rupture
Mitral valve more commonly Severe regurgitation with a rapid change in haemodynamic status Sudden death or signs of acute cardiac failure - can compensate in the long term if they live beyond the acute crisis of chord rupture.
53
What are the different chordae tendinae rupure locations?
BREAKS AT PAPILLARY MM ==> instant and incomplete loss of valve function ==> HF ==> instant death BREAKS AT VALVE LEAFLET ==> partial valve failure ==> horse MAY survive with left-sided HF.
54
What can AV valvular regurgitation develop secondary to?
- Severe ventricular dilation - Cardiomyopathy and myocardial disease - AoR adn LV volume overload. Mitral and/or tricuspid regurgitation appear later in disease - important to differentiate and identify the primary problem.
55
What happens in LV volume overload to ventricular shape?
Ventricle develops globoid shape with rounded apex.
56
Name 2 other (poorly defined) causes of murmurs in horses
- Right and left ventricular hypertrophy (athletes) | - Hypovolaemia
57
Outline right and left ventricular hypertrophy in equine athletes as a cause of murmur
Usually mild and non-progressive Particularly affecting the tricuspid valve Can be considered as physiological regurgitation
58
Outline hypovolaemia as a poorly defined cause of equine murmurs
Many horses presenting with acute colic/systemic disease often have 'new' cardiac murmurs that resolve once the primary disease has been treated (i.e. they are transient)
59
Name 3 congenital abnormalities in horses
VSD - most common, about 90% congenital defects PDA - about 10% congenital defects Valve dysplasia
60
Outline VSDs in large animals
Most common congenital cardiac defect Defect is in dorsal (membranous) part of septum 2 murmurs --> 'diagonal' murmur RHS murmur associated with LV to RV shunt LHS murmur associated with RV overload ('functional' pulmonic stenosis) ****Intensity is inversely proportional to the size of the defect - i.e. loud does not always mean severe = opposite of many other pathologies ***
61
Describe VSD murmurs located on RHS
holo-pansystolic, coarse, plateau, grade 3-6, PMI tricuspid valve, wide radiation
62
Describe VSD murmurs located on the LHS
Holo-pan systolic, crescendo-decrescendo, grade 3-6, wide radiation
63
Prognosis VSD
Very small defect are NOT life-threatening and horses with small VSDs can enter training - so keep this murmur on your differential list, even in older horses!
64
Outline PDA in horses
Normally remains patent in foals for up to 7-10 days old (don't overdiagnose!). Closes earlier in FA. Blood flows along the PDA in both systole and diastole producing a continuous 'washing machine' murmur, grade 3-5, wide radiation, PMI = left heart base, radiates to RHS
65
T/F: in most foals, if you can hear a murmur over the left heart base after 10 days old, this is likely to be abnormal
True (BUT some foals (minority) may take up to a month for the PDA to close)
66
Name 2 murmurs in horses that aren't clinically signficiant
Flow murmurs | Functional valve regurgitations
67
T/F: in horses, the CSs of cardiac disease may be subtle
True
68
What is the aim of examining a horse with a murmur?
- Determine if the murmur is significant at the time | - Determine if the murmur will become significant - i.e. is it a progressive murmur?
69
How do you best assess cause, significant and prognosis of equine murmurs?
Ultrasonography (i.e. echocardiography)
70
What are the normal heart sounds in cattle?
S1, S2 and S4 (i.e. no S3 unlike horses)
71
Outline valvular dysplasia
Congenital Uncommon in large animals Rarely well tolerated and usually part of complex congenital cardiac disease.

Cardiovascular (22 decks)

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