Heart sounds

Question 1

What are S1 and S2 due to?

Answer 1

S1: lub. AV valves closing

S2: dub. Semilunar valves closing

S1 is longer than S2

Question 2

Diff in S2 between inspiration and expiration

Answer 2

Expiration: Aortic and pulmonary valves close at the same time

Inspiration: Separation between aortic and pulmonary valves closing. Aortic closes first and then pulmonary

Question 3

When do systole and diastole occur in relation to S1 and S2?

Answer 3

S1, systole, S2, diastole

Question 4

When can you palpate the carotid pulse (in relation to S1 and S2)

Answer 4

Between S1 and S2 i.e. after systole but before diastole.

So when AV valves have closed but semilunar valves are open

Question 5

When do you hear S3?

Answer 5

(GALLOP RHYTHM)

Heard in early diastole – KEN—TUC-KY (emphasis on KEN)

Represents thin walled, dilated left ventricle causing decelerated blood flow

Normal in children and athletes, in normal adults can indicate ventricular systolic failure

Question 6

When do you hear S4?

Answer 6

• heard in late diastole just before S1 – TEN-NE—SEE (emphasis on the SEE. But S4 is TEN. four-one-TWO, four-one-TWO)

Occurs due to increased stiffness of left ventricle, or thicker ventricular wall

Associated with severe hypertension and ventricular hypertrophy.

*can also be caused by AORTIC STENOSIS*

Question 7

What are the 2 systolic murmurs and overall where do they occur?

Answer 7

1. Aortic (or pulmonary) stenosis
2. Mitral (or tricuspid) regurgitation

They occur between S1 and S2. i.e. during systole

(narrowed semilunar valve, leaky AV valve)

Question 8

Describe aortic stenosis

Answer 8

• leads to mid-systolic murmur
• as AV valve is narrowed it’s difficult for blood to flow from LV to aorta during systole
• crescendo-decrescendo nature

Question 9

Describe mitral regurgitation

Answer 9

• results in a pan-systolic murmur
• as AV valve is leaky, during ventricular contraction there is backflow thus causing a murmur
• the reason it encompasses ALL of systole is because the pressure in the atria is ZERO so there’s no resistance

Question 10

What are the 2 types of diastolic murmurs and overall where do they occur?

Answer 10

1. Aortic regurgitation
2. Mitral stenosis

Occur between S2 and the next S1.

(leaky semilunar valve, narrowed AV valve)

Question 11

Describe mitral stenosis

Answer 11

• leads to a MID DIASTOLIC MURMUR
• the beginning of diastole is passive flow from atria to ventricles. There’s an OPENING SNAP as valve suddenly opens to let blood through
• As the mitral valve is narrowed there is a murmur as blood flows downwards from A–>V passively.
• There is PRE-SYSTOLIC ACCENTUATION. i.e. the murmur gets LOUDER at the end of diastole, when the atria CONTRACT to push the last bit of blood from A to V.
• S1 is loud. This is because narrowed valve means LEAFLETS are wide open, so when they close (at S1) it is loud

Question 12

Describe aortic regurgitation

Answer 12

• leads to EARLY diastolic murmur
• systole is normal as blood flows from LV to aorta via open aortic valve
• but in early diastole as the aortic valve is leaky, blood flows back down from aorta to LV
• > DESCRESCENDO MURMUR. it gets quieter as the pressure in the aorta FALLS (from about 140) and equalises with pressure in LV
• WIDE PULSE PRESSURE- because in diastole blood suddenly flows back from aorta, causing a DROP in BP

–>QUINKE’S SIGN (visible pulsations in nailbed)

Question 13

Which murmurs are heard better in inspiration and expiration?

Answer 13

• Expiration increases L-sided murmurs
• Inspiration increases R-sided murmurs

Because, during inspiration, there is more negative intra-thoracic pressure which pulls more venous blood into the heart (to the right side) so there is increased preload to R side. At same time, during inspiration, pulmonary blood volume increases and there is a decrease in blood flow from lungs to left atrium so there is decreased preload to L side.