Heart sounds and murmurs

Question 1

What are the heart sounds?

Answer 1

They represent the closure of the heart valves.

Question 2

How many heart sounds are there?

Answer 2

There are 4 heart sounds.
The first 2 are normal.
The third one is pathological over the age of 30.
The fourth one is always abnormal.

Question 3

How are you meant to listen to the heart sounds?

Answer 3

Place your stethoscope on the landmarks of the valves.
Aortic valve- R 2nd intercostal space parasternal
Pulmonary valve- L 2nd intercostal space parasternal
Tricuspid valve- L 4th intercostal space parasternal
Mitral valve- L mid-clavicular line 5th intercostal space
Listen systematically, sounds then murmurs.
While listening, palpate the carotid artery- S1 is synchronous with the upstroke.

Question 4

What does the 1st heart sound represent?

Answer 4

S1 represents the closure of the mitral and tricuspid valves.
Splitting in inspiration may be heard and is normal.

Question 5

Abnormalities of S1

Answer 5

Loud S1: In mitral stenosis- the narrowed valve orifice limits ventricular filling, there is no gradual decrease inflow towards the end of diastole.
Soft S1: Occurs if the diastolic filling is prolonged e.g. prolonged PR interval or if the mitral valve leaflets fail to close properly (i.e. mitral incompetence)
The intensity of S1 is variable in AV block, AF and nodal or ventricular tachycardia.

Question 6

What does the 2nd heart sound represent?

Answer 6

S2 represents aortic and pulmonary valve closure.
In the normal heart:
During expiration:
The second sound (S2) is usually single
During inspiration:
The second sound (S2) is made of two-component sounds:
Aortic valve closure (A2) which happens first.
Pulmonic valve closure (P2) which happens second.

Question 7

Which S2 is louder?

Answer 7

A2 is heard widely all over the chest. So when you hear ‘S2’ at the mitral area, you are really hearing A2.
Normally, P2 is soft and only heard at the pulmonic region (left parasternal, intercostal space 2), however, even in this region, A2 is louder.

Question 8

What is the most important abnormality of A2?

Answer 8

Softening in aortic stenosis

Question 9

What increases the intensity of A2?

Answer 9

Tachycardia
Hypertension
Transposition

Question 10

What increases the intensity of P2?

Answer 10

DDx: pulmonary hypertension (most common), the atrial septal defect (ASD) will also increase P2
Note: Since P2 is measured relative to A2, causes for lower A2 intensity should be ruled out. These include: mitral regurgitation, aortic regurgitation, low diastolic arterial pressure, severe immobile aortic valve disease

Question 11

What causes wide splitting of S2?

Answer 11

Detected by the presence of splitting during expiration, wider during inspiration
DDx: Anything that causes delayed conduction down the right bundle (RBBB, pre-excitation of the left ventricle, the pacing of the left ventricle, premature LV beats), pulmonary stenosis, pulmonary arterial hypertension, deep inspiration and mitral regurgitation.

Question 12

What causes wide fixed splitting of S2?

Answer 12

Spitting at both expiratory and inspiratory phases but does NOT lengthen with inspiration
Dx: ASD (due to continuous blood flow from the left side to right side leading lengthened cardiac cycle on the right side of the heart), Right heart failure, Pulmonary Hypertension.

Question 13

What causes paradoxical splitting of S2?

Answer 13

The reverse of normal physiology, splitting of second heart sounds during expiration, singular during inspiration

Dx: Anything that causes delayed conduction down the left bundle (LBBB, pre-excitation of the right ventricle, right ventricular pacing, premature RV beats), aortic stenosis

Question 14

What causes a single S2 sound?

Answer 14

Either from loss of A2 or loss of P2
DDx: Severe aortic stenosis, severe aortic regurgitation, congenital absence of pulmonary valve
Note: in patients with difficult to hear heart sounds (obesity, emphysema, pericardial fluid), P2 may be too hard to hear causing a single (A2) heart sound

Question 15

What is the 3rd heart sound?

Answer 15

This may occur just after S2.
It is low-pitched and is best heard with the bell of the stethoscope.
S3 is pathological over the age of 30 years.
A loud S3 occurs in a dilated left ventricle with rapid ventricular filling (mitral regurgitation, VSD) or poor LV function (post-MI, dilated cardiomyopathy).

Question 16

What is the 4th heart sound?

Answer 16

This occurs just before S1.
Always abnormal and it represents atrial contraction against a ventricle made stiff by any cause e.g. aortic stenosis or hypertensive heart disease.

Question 17

What is an ejection systolic click?

Answer 17

This is heard early in systole just after the first heart sound.
The sounds occur in the presence of a dilated aorta or pulmonary artery or in the presence of a bicuspid or flexible stenotic aortic or pulmonary valve.

Question 18

When does a mid-systolic click occur?

Answer 18

This occurs in a mitral valve prolapse.

Mitral valve prolapse may also produce a late systolic murmur.

Question 19

What is an opening snap?

Answer 19

An opening snap occurring early in diastole along with a single second heart sound can mimic a split second heart sound.
The opening snap precedes the mid-diastolic murmur of mitral (and tricuspid) stenosis.
An opening snap is caused by thickened valve leaflets. When they open it produces a snapping sound.
The more severe the thickening the earlier in diastole the opening snap occurs.

Question 20

What causes prosthetic sounds?

Answer 20

This is caused by non-biological valves, on opening and closing.

Question 21

What are heart murmurs?

Answer 21

Heart murmurs are sounds during your heartbeat cycle — such as whooshing or swishing — made by turbulent blood in or near your heart.

Question 22

How should assess cardiac murmurs?

Answer 22

Character, timing, loudness, the area where loudest, radiation and accentuating manoeuvres.

Question 23

Describe an ejection systolic murmur (ESM)

Answer 23

ESM usually originates from the outflow tract and waxes and wanes with the intraventricular pressures.
ESMs may be innocent and are common in children and high-output states.
Organic causes include aortic stenosis and sclerosis, pulmonary stenosis.

Question 24

Describe a pansystolic murmur (PSM)

Answer 24

This is of uniform intensity and merges with S2.
It is usually organic and occurs in mitral or tricuspid regurgitation (S1 may also be soft in these) or a ventricular septal defect.

Question 25

Describe an early diastolic murmur (EDM)

Answer 25

They are high pitched and easily missed.
Listen for the absence of silence in early diastole.
EDM occurs in aortic and pulmonary regurgitation.

Question 26

What is a Graham Steell murmur?

Answer 26

This is when pulmonary regurgitation is secondary to pulmonary hypertension resulting from mitral stenosis.

Question 27

Describe a mid-diastolic murmur (MDM)

Answer 27

They are low pitched and rumbling.

They occur in mitral stenosis, rheumatic fever and aortic regurgitation (Austin Flint murmur)

Question 28

Intensity of murmurs

Answer 28

All murmurs are graded on a scale of 1-6, though in practice diastolic murmurs, being less loud are only graded 1-4.
Intensity is a poor guide to the severity of a lesion.
Grade 1- very soft
Grade 2- soft but detectable immediately
Grade 3- clearly audible, but no thrill palpable
Grade 4- clearly audible, palpable thrill
Grade 5- audible with stethoscope only partially touching chest
Grade 6- can be heard without placing a stethoscope on chest

Question 29

Where do murmurs radiate to?

Answer 29

Aortic stenosis radiates to the carotids

Mitral regurgitation radiates to the axilla

Question 30

Accentuating manoeuvres for murmurs

Answer 30

Movements- bring relevant part of heart closer to the stethoscope; leaning forward for aortic regurgitation and left lateral position for mitral stenosis.

Expiration- Increases blood flow to the left side of the heart and therefore accentuates left-sided murmurs.

Valsalva manoeuvre- forced expiration against a closed glottis decreases systemic venous return, accentuating mitral valve prolapse and HOCM but softening mitral regurgitation and aortic stenosis.

Question 31

Describe pericardial friction rub

Answer 31

A pericardial friction rub may be heard in pericarditis- this is a superficial scratching sound, not confined to systole or diastole.

Question 32

What is a murmur called if it occurs outside of the heart?

Answer 32

Turbulent blood flow can occur anywhere in the body.

Turbulent blood flow outside the heart is known as a bruit.

Question 33

When does a murmur occur?

Answer 33

The chance a flow will be turbulent is dependent upon its Reynold’s number

Question 34

Aetiologies of the heart murmurs

Answer 34

Decreased blood viscosity- anaemia
The decreased diameter of vessel, valve, or orifice- valvular stenosis, coarctation of the aorta, VSD
Increased velocity of blood- hyperdynamic state such as sepsis and thyrotoxicosis
Regurgitation of blood through an incompetent valve- valvular regurgitation

Question 35

What can cause a continuous murmur through systole and diastole?

Answer 35

Patent ductus arteriosis.