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Cardiovascular > Endocardial Disease in Large Animals: Cardiac Murmurs > Flashcards

Endocardial Disease in Large Animals: Cardiac Murmurs Flashcards

1
Q

What are the 3 categories of heart murmurs in the large animal and give examples of each?

A

Not associated with valve pathology
+ physiological murmurs in the horse, functional valve regurg

Associated with valve pathology
+ Endocarditis, valve degeneration/prolapse, ruptured chordae tendinaeae

Congenital abnormailites
+ VSD, PDA, valvular dysplasia

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2
Q

Following cardiac auscultation, how might you further evaluate a cardiac murmur?

A

Echocardiography
+ Confirmation of diagnosis
+ Assess severity
+ Determine prognosis

Electrocardiography
+ Little value in murmurs assessment
+ But may identify concurrent arrhythmias

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3
Q

What types of echocardiography can be used?

A

2D and M mode

Doppler

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4
Q

What can 2D and M-mode echo be used to assess?

A

Valve structure and function
Chamber size
Myocardium

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5
Q

Describe 2D echocardiography imaging

A

Allows structures to be viewed moving in real time in a cross-section of the heart

Detects abnormal anatomy or movement of the structures

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6
Q

Describe M-mode echocardiaography imaging.

A

Provides a 1D view

Used for fine measurements

Temporal and spatial resolutions are higher because the focus is on only one of the lines from the 2D trace

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7
Q

Describe doppler imaging..

A

Estimates of blood-flow velocity made by comparing the frequency change between the transmitted and reflected sound waves

Continuous wave, pulsed wave or colour flow mapping

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8
Q

What type of blood flow produces a murmur?

A

Turbulent

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9
Q

Describe aortic flow murmurs in horses…

A

Physiological murmur
Early-mid systolic crescendo to decrescendo
Common
Quiet (< Grade III)
PMI aortic valve or heart base
Effect of exercise variable, but generally disappears as the turbulent flow becomes laminar
Normal, especially in fit horses

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10
Q

What is the diameter of the aorta in a thoroughbred?

A

10-12cm

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11
Q

Describe ventricular flow murmurs in the horse…

A 
Physiological murmur
Early diastolic
Mitral and tricuspid waves
Less common than aortic flow
Short duration
High pitched 'squeak'
After S2 but before S3
PMI heart base or AV values
Normal, especially in young TBs but usually disappears with age
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12
Q

Which valve does valve regurgitation most commonly occur in in the horse?

A

Mitral > Tricuspid > Aortic

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13
Q

Is valve regurgitation significant in the horse?

A

Many are non-progressive “functional regurgitations”

Or may be associated with valve pathology (significance is related to cause, they may be progressive or have a sudden onset and can be fatal)

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14
Q

How can you differentiate between a pathological and function valve regurgitation?

A

Echo

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15
Q

Why does valve regurgitation occur in the healthy horse?

A

Physiological phenomenon in fit and healthy animals.

Valves can’t quite close as the heart gets bigger, so there is a small amount of regurgitation

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16
Q

What % of horses in training have valve regurgitation?

A

30%

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17
Q

Describe mitral regurgitation in the horse…

A

Systolic murmur
Significance and auscultation findings vary with cause (quiet may be functional murmur)
Differentiate by observing progression over time
Intensity and radiation increases with severity
PMI left 5 rib

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18
Q

How can mitral regurgitation lead to collapse and death in the horse

A

Flow from the left ventricle to the left atria leads to high pressures in the left atria. The pressure builds up in the pulmonary veins, circulation and artery. These can rupture as a consequence of forward and backward pressure.

19
Q

At what intensity can 3+ murmurs be heard at the opposite chest wall of a horse?

A

At the volume of a murmur 2 grades lower (radiates across)

20
Q

Describe tricuspid regurgitation in the horse..

A

Significance and auscultation findings vary with the cause (may be a quiet “functional” murmur

Intensity and radiation increase with severity

Intensity is between 1 and 6 out of 6

Can be heard early, mid, holo or pan systolic

Have a plateau shape

PMI right 4th intercostal space (apex)

Radiates craniodorsally

21
Q

When might mitral regurgitation be significant in the horse?

A 
When associated with poor performance
Resting tachycardia
Abnormal pulse, slow CRT
Signs of LSHF
Arrhythmias, particularly AF
Louder than grade 4
Wide radiation
22
Q

What is aortic regurgitation often due to in the horse?

A

Endocardiosis

23
Q

Describe aortic regurgitation in the horse…

A

Common in older horses

Incidental finding

Often slowly progressive

Intensity between 1 and 6

Holodiastolic between S2 and S4

Decrescendo sound

PMI is aortic valve

24
Q

When might tricuspid regurgitation be significant in the horse?

A 
Associated with poor performance
Resting tachycardia
Abnormal pulse
Signs of right sided failure
Arrhythmias, especially atrial fibrillation
Louder than grade 4
Wide radiation
25
Q

What are the top 3 causes of poor performance in horses?

A

Lameness
Respiratory
CVS

26
Q

When may aortic regurgitation be significant?

A

Associated with poor performance

Resting tachycardia

Bounding “hyperkinetic” arterial pulse
+ due to large systolic/diastolic pressure difference (regurgitation into the left ventricle)

Slow CRT

Signs of left sided heart failure

Arrhythmias, especially atrial fibrillation

27
Q

What are the common causes of murmurs associated with valve pathology in large animals?

A

Degenerative valve disease

Bacterial endocarditis

28
Q

What are the chorda tendonae attached to?

A

Papillary muscles

29
Q

What does bacterial endocarditis occur secondary to?

A

Bacteraemia

30
Q

What are the usual primary sites of bacteraemia in bacterial endocarditis of cattle?

A 
Liver abscess
Traumatic reticulitis
Metritis
Mastitis
Navel abscess
"Joint ill"
31
Q

How would you diagnose bacterial endocarditis?

A

Clinical signs:
Congestive heart failure
Fever, cardiac murmur, tachycardia, tachypnoea

Clinical pathology:
Hyperfibrinogenaemia, anaemia and leucocytosis
Blood culture

32
Q

What areas of the heart are usually affected by bacterial endocarditis in:

a. Ruminants
b. Horses
c. Pigs

A

a. Tricuspid and pulmonic valves. Right ventricular endocaridum.
b. Mitral >aortic. Can include aortic root. Right sided associated with jugular thrombophlebitis
c. Mitral, aortic

33
Q

What is the prognosis for animals affected by bacterial endocarditis?

A

Guarded even following bacterial cure as permanent structural damage to valve. In horses some RHS lesions may have retruned performance

Septic emboli may shed to distant sites e.g. lung, kidneys and joints

34
Q

What do you need to diagnose valvular prolapse?

A

Echo

35
Q

What are ruptured chordae tendinae a common cause of?

A

Horses collapsing and dying at exercise

36
Q

What can ruptured chordae tendinae arise as a result of?

A

Spontanteously or secondary to inflammatory or degenerative changes

37
Q

What congenital abnormalities can lead to murmurs?

A

VSD
PDA
Valve dysplasia

38
Q

Describe VSD in large animals..

A

Most common congenital cardiac defect in large animals

In almost all VSDs the defect is in dorsal (membranous) part of the septum, but may be a patent ductus arteriosis

2 murmurs producing a “diagonal” murmur

RHS murmur is associated with the LV to RV shunt

LHS murmur is associated with RV overload, “functional” pulmonic stenosis

Intensity is inversely proportional to the size of the defect (loud does not always indicate severe, large VSDs produce less turbulence so are quieter)

39
Q

When does the ductus arteriosus normally remain patent till in the foal?

A

7-10 days

40
Q

Describe RHS and LHS VSD murmurs in large animals…

A 
RHS
Holo-pansystolic
Coarse
Plateau
Grade 3-6
PMI tricuspid valve
Wide radiation
LHS
Holo-pansystolic
Crescendo-decrescendo
Grade 3-6
Wide radiation
41
Q

Describe patent ductus arteriosus

A

Blood flows along PSA in both systole and diastole producing a washing machine murmur

Grade 3-5, with wide radiation

PMI is at the LH base and radiates to RHS

42
Q

What is the cause of aortic murmurs?

A

The diameter of the aorta is large so can get non-laminar flow at rest

43
Q

What are the causative agents of bacterial endocarditis in:

a. ruminants
b. horses
c. pigs

A

a. Enterococci, Streptococci, Actinomyces pyogenes
b. Pasteurella, Acintobaccillus, Streptococci, Rhodococcus equi
c. Staph aureus, Actinobacillus suis, Erysipelothrix rhysiopathiae

Cardiovascular (10 decks)

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