Equine Cardiac examination Refresher and Murmurs

Question 1

How does cardiac disease most commonly present in horses?

Answer 1

• Incidental e.g. pre-purchase exam
• History of poor performance
• Systemically ill horse
• Horse presented with evidence of heart failure (rare)

Question 2

What are the aims of investigation when investigating cardiac disease in horses?

Answer 2

Need to establish significance of any findings:
- Cardiac murmurs/dysrhythmias are COMMON
- Significance for performance?
- Collapse?
- Progression?
- Interpret in context of use/intended use of horse

Question 3

Describe how to auscultate a horses heart

Answer 3

1. Quiet environment
2. Take time
3. Let horse settle
4. Get into the rhythm
   Listening on the RHS:
   - Pull leg forward
   - Stick stethoscope bell right under triceps just dorsal to point of elbow

Question 4

The apex beat in horses correlates to which valve?

Answer 4

Mitral

Question 5

Name the valve that lies between the right atrium and ventricles

Answer 5

Tricuspid valve

Question 6

Name the valve that lies between the left atrium and ventricles

Answer 6

Mitral

Question 7

Systole = ?
Diastole = ?

Answer 7

Systole = contraction
Diastole = relaxation

Question 8

Describe the S1 and S2 heart sounds

Answer 8

Ventricles contract:
- S1 : Shutting of AV valves (Mitral/tricuspid)
- “ LUB “
Ventricles relax
- S2 : Shutting of Semilunar valves (Aortic/Pulmonic)
- “ DUP “

Question 9

Describe the other heart sounds heard in a horse

Answer 9

S4: atrial contraction
- “ B “ Very common
- Just before S1
S3: end of rapid ventricular filling
- “ D “ Less common
- Just after S2

Question 10

How does mitral valve regurgitation affect the heart sounds in horses?

Answer 10

Causes a loud S3 due to lots of blood going back into the atrium, it is now full of blood, when the ventricle relaxes lots of blood rushes in, causing a loud sound

Question 11

Describe which heart sounds are loudest in the basal and apical areas of the heart

Answer 11

Basal - S1 quieter, S2 louder
Apical - S1 louder, S2 quieter

Question 12

Describe the lengths of systole and diastole in the normal heart - normal HR

Answer 12

Systole is much shorter than diastole

Question 13

Describe the lengths of systole and diastole in the normal heart - high HR

Answer 13

Duration of systole = Duration of diastole

Question 14

What is a murmur?

Answer 14

Turbulence of blood flow

Question 15

Reynolds number influences?

Answer 15

Turbulence

Question 16

Describe the sound made by normal laminar flow of blood

Answer 16

None - silent

Question 17

Which factors influence turbulence of blood?

Answer 17

Stenosis of a vessel
Valve regurgitation
Increased blood flow

Question 18

List the 6 methods of describing murmurs

Answer 18

• Grade
• Timing
• Point of maximal intensity
• Radiation
• Shape of murmur
• Quality of the murmur

Question 19

Describe the 6 grades of heart murmurs

Answer 19

1 = barely audible
2 = definite murmur quieter than S1 and S2
3 = obvious murmur as loud as S1 and S2
4 = very loud murmur, louder than S1 and S2
5 = very loud and has a palpable thrill
6 = audible with stethoscope just off chest wall

Question 20

Describe how the timing of murmurs can be used to describe them

Answer 20

Systolic / diastolic / continuous
- Early
- Mid
- Late
- ‘Pan’
- ‘Holo’

Question 21

Describe the meaning of the term ‘pan’ used to describe the timing of murmurs

Answer 21

Fills up the whole of systole and you can’t hear the heart sounds at either end

Question 22

Describe the meaning of the term ‘holo’ used to describe the timing of murmurs

Answer 22

Fills up the whole of systole but can hear the heart sounds at either end

Question 23

How can the shape of the murmur be used to describe it?

Answer 23

‘Plateau’
Crescendo
Decrescendo
Crescendo/decrescendo

Question 24

Name the 2 categories of murmurs

Answer 24

• Physiological/functional
• Pathological

Question 25

Physiological/functional murmurs are associated with..?

Answer 25

Normal blood flow through heart

Question 26

Physiological/functional murmurs are associated with..?

Answer 26

Normal blood flow through heart

Question 27

Pathological murmurs are associated with..?

Answer 27

Underlying cardiac disease

Question 28

Name the two main types of pysiological/functional murmurs

Answer 28

Flow murmur Filling murmur

Question 29

Describe the features of flow murmurs

Answer 29

- Early-mid systole - Up to 60% normal horses; L>R - Localised over heart base (aorta) - May change intensity with HR/exercise - Always finish before S2 - Crescendo-decrescendo

Question 30

Describe the features of filling murmurs

Answer 30

- Early diastole, L or R - Fit, young animals - Squeak / whoop/ click - Short duration between S2 & S3 - Localised over heart base or apex - May change intensity with HR - Associated with turbulence of blood as it flows into the ventricles in early diastole, but before the walls stop

Question 31

How common is primary valvular stenosis in horses?

Answer 31

Rare

Question 32

Describe the murmur caused by Mitral/Tricuspid (AV Valve) regurgitation

Answer 32

- Holo/pansystolic - Plateau or crescendo - PMI heart apex - May radiate dorsal and cranial

Question 33

At what grades of mitral valve regurgitation is it advised to monitor that horse and what grades require further investigation?

Answer 33

Grade 1-2: Monitor Grade 3-6: Advise further investigation

Question 34

At what grades of tricuspid valve regurgitation is it advised to monitor that horse and what grades require further investigation?

Answer 34

Grade 1-3: monitor Grade 4-6: advise further investigation

Question 35

Describe the pathological murmur caused by a ventricular septal defect

Answer 35

Loudest on right (occ. left) Loud – thrill Radiate cranial/ventral Pansystolic Normally young horses

Question 36

Describe the pathological murmur caused by aortic insufficiency

Answer 36

Common older horses Descrescendo, buzzing / cooing Holodiastolic PMI left heart base May radiate ventrally

Question 37

Which murmur of horses is referred to as the 'teenage murmur'?

Answer 37

Aortic regurgitation

Question 38

Name the pathological continuous ‘machinery’ Murmur of horses

Answer 38

Patent Ductus Arteriosus

Question 39

When is a PDA murmur normal?

Answer 39

In neonates up to 5do

Question 40

Describe the murmur caused by a patent ductus arteriosus

Answer 40

PMI left heart base, also loud right heart base Waxes and wanes in intensity during cardiac cycle

Question 41

Name 2 physiological murmurs of horses

Answer 41

Aortic flow murmurs Ventricular filling murmurs

Question 42

Name 4 pathological murmurs of horses

Answer 42

Mitral/tricuspid valve regurgitation Aortic regurgitation Ventricular septal defect (Patent Ductus arteriosus)

Question 43

Name two left and two right systolic murmurs

Answer 43

Left - Mitral valve regurgitation - Aortic flow murmur Right - Tricuspid regurgitation - Ventricular septal defect

Question 44

Name two left diastolic murmurs

Answer 44

- Aortic valve regurgitation - Ventricular filling defect