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Cardiovascular > Equine murmurs > Flashcards

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
Q

What is an early/mid/late systolic murmur?

A

When the valve leaks only for a part of systole.

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26
Q

Name 3 common pathological valve regurgitations - horses

A

Mitral
Tricuspid
Aortic
(Pulmonic - very uncommon)

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27
Q

Why may the PA rupture in mitral regurgitation?

A

Due to PA back pressure and forward pressure –> PA rupture –> sudden death of the equine

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28
Q

How common are stenoses in horses?

A

Very rare - shouldn’t be on an everyday DDx list. (this includes valve and OT stenoses)

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29
Q

Outline tricuspid regurgitation (TR) in horses

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: right 4th ICS
RADIATES: craniodorsally
30
Q

What is aortic regurgitation (AoR) often due to?

A

Endocardiosis (this cause is much more likely than for MR or TR).

31
Q

Outline aortic regurgitation (AoR)

A 
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
Q

When might MR be significant? 7

A 
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
Q

When might TR be significant? 7

A 
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
Q

When might AoR be significant? 6

A

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
Q

List some common causes of murmurs associated with valve pathology

A
  • Degenerative valvular heart disease (endocardiosis) - commonest valve pathology
  • Bacterial endocarditis
36
Q

T/F: many valve regurgitation sin horses are NOT associated with obvious valve pathology

A

True

37
Q

Outline bacterial endocarditis - horses and ruminants

A

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
Q

Why is prompt treatment of bacterial endocarditis important?

A

Large proliferative ‘vegetative’ lesions may develop, limiting prospects for return to normal valve function.

39
Q

Causative organisms - ruminants - bacterial endocarditis

A

Enterococci
Streptococci
Actinomyces pyogenes

40
Q

Causative organisms - horses - bacterial endocarditis

A

Pasteurella
Actinobacillus
Streptococci
Rhodococcus equie

41
Q

Causative organisms - pigs - bacterial endocarditis

A

Staph. aureus
Actinobacillus suis
Erysipelothrix rhusiopathie

42
Q

Area of ruminant heart affected in bacterial endocarditis

A

Tricuspid and pulmonic valves

Right ventricular endocardium

43
Q

Area of equine heart affected in bacterial endocarditis

A

Mitral>aortic
Can include aortic root
Right-sided associated with jugular thrombophlebitis

44
Q

Area of swine heart affected in bacterial endocarditis

A

Mitral, aortic (usually PM finding)

45
Q

Diagnosis - heart murmurs associated with pathology

A

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
Q

Tx - bacterial endocarditis

A

BS AB based on sensitivity

47
Q

Prognosis - bacterial endocarditis

A

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
Q

Name 2 less common causes of murmurs associated with valve pathology

A

Valve prolapse

Ruptured chordae tendinae

49
Q

Outline valve prolapse

A

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
Q

Name 2 causes of sudden death in horses related to CVS

A

Ruptured chordae tendinae

Ruptured PA

51
Q

When might chordae tendinae be ruptured?

A

Spontaneously OR secondary to inflammatory or degenerative changes in the chordae.

52
Q

Outline chordae tendinae rupture

A

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
Q

What are the different chordae tendinae rupure locations?

A

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
Q

What can AV valvular regurgitation develop secondary to?

A
  • 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
Q

What happens in LV volume overload to ventricular shape?

A

Ventricle develops globoid shape with rounded apex.

56
Q

Name 2 other (poorly defined) causes of murmurs in horses

A
  • Right and left ventricular hypertrophy (athletes)

- Hypovolaemia

57
Q

Outline right and left ventricular hypertrophy in equine athletes as a cause of murmur

A

Usually mild and non-progressive
Particularly affecting the tricuspid valve
Can be considered as physiological regurgitation

58
Q

Outline hypovolaemia as a poorly defined cause of equine murmurs

A

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
Q

Name 3 congenital abnormalities in horses

A

VSD - most common, about 90% congenital defects
PDA - about 10% congenital defects
Valve dysplasia

60
Q

Outline VSDs in large animals

A

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
Q

Describe VSD murmurs located on RHS

A

holo-pansystolic, coarse, plateau, grade 3-6, PMI tricuspid valve, wide radiation

62
Q

Describe VSD murmurs located on the LHS

A

Holo-pan systolic, crescendo-decrescendo, grade 3-6, wide radiation

63
Q

Prognosis VSD

A

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
Q

Outline PDA in horses

A

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
Q

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

A

True (BUT some foals (minority) may take up to a month for the PDA to close)

66
Q

Name 2 murmurs in horses that aren’t clinically signficiant

A

Flow murmurs

Functional valve regurgitations

67
Q

T/F: in horses, the CSs of cardiac disease may be subtle

A

True

68
Q

What is the aim of examining a horse with a murmur?

A
  • Determine if the murmur is significant at the time

- Determine if the murmur will become significant - i.e. is it a progressive murmur?

69
Q

How do you best assess cause, significant and prognosis of equine murmurs?

A

Ultrasonography (i.e. echocardiography)

70
Q

What are the normal heart sounds in cattle?

A

S1, S2 and S4 (i.e. no S3 unlike horses)

71
Q

Outline valvular dysplasia

A

Congenital
Uncommon in large animals
Rarely well tolerated and usually part of complex congenital cardiac disease.

Cardiovascular (22 decks)

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