Heart Sounds

Question 1

S4

Answer 1

-occurs during atrial contraction at end of diastole

Question 2

S1

Answer 2

-occurs during isovolumetric contraction; mitral and tricuspid valves close

Question 3

S2

Answer 3

-occurs during isovolumetric relaxation; aortic and pulmonic valve closure

Question 4

S3

Answer 4

-occurs during rapid and reduced filling (diastole)

Question 5

What are you hearing in all animals?

Answer 5

-will hear S1 (closing of mitral and tricuspid valves) and S2 (closing of aortic and pulmonic valves) = “Lub, Dub”
- in horses and cows, there is potential to hear S3 (inflow during diastole, oscillation of blood in ventricles) and S4 (vibration of ventricular wall during atrial systole/contraction)

Question 6

Why can you hear S3 and S4 in horses and cows?

Answer 6

-hearts are much larger, and heart rates are much slower
S3 and S4 in smaller animals would mean an abnormality (cardiac hypertrophy)

Question 7

Splits and systolic clicks

Answer 7

-Splits: heard when two valves are closing asynchronously (often occurs at S2 due to blockage at bundle branches, also when afterload is different on either side of heart)

-Clicks: AV valves prolapsing and moving back into atrium (during systole when pressure increases)

Question 8

Stenosis

Answer 8

-narrowing of the valve opening, causing a greater pressure differential/gradient

Question 9

Regurgitation

Answer 9

-valvular insufficiency, causing backward flow of blood and turbulent flow

Question 10

Systolic murmurs

Answer 10

-during contraction of heart
-crescendo between S1 and S2
-turbulent flow
-caused by aortic or pulmonic valve stenosis, and mitral valve regurgitation

Question 11

Pressure changes during aortic stenosis/systolic murmur

Answer 11

Left ventricular pressure greatly increased compared with aortic pressure
- Aortic pressure is actually reduced compared to normal as well
- Pressure gradient across the valve is very high resulting in increased resistance for left ventricle (increased afterload)
- Will also result in turbulence

Stenosis increases afterload, reduces stroke volume, and decrease in aortic pulse pressure. Blood pressure will decrease

Will have impaired filling (diastole) and reduced compliance. Reason for higher filling pressure (right atrial pressure), which can also result in backflow in pulmonary veins

Question 12

Mitral valve regurgitation and systolic murmur

Answer 12

• Mitral valve fails to close properly during ventricular systole causing blood to flow back into the left atrium causing it to become engorged with blood because getting blood from left ventricle and the pulmonary vein
• LV preload increases, stroke volume decreases (because divided into two areas instead of just aorta)

Question 13

Holosystolic (or pansystolic)

Answer 13

-sound intensity remains constant
-backflow
-caused by mitral or tricuspid regurgitation

Question 14

Diastolic murmurs

Answer 14

-decrescendo between S2 and S1caused by aortic or pulmonic regurgitation
-delayed beyond S2, decrescendo with an uptick with atrial contraction caused by mitral (or tricuspid)valve stenosis
-back flow during diastole back into the left ventricle (left ventricle being filled by aorta and left atria)

Question 15

Pressures during diastolic murmur (aortic regurgitation)

Answer 15

-increased ventricular filling (preload), EDV and SV increased and therefore EDP will be increased (in both left ventricle and left atria- results in backing up in pulmonary veins as well)
-will increase contractility of heart and increase systolic blood pressure during ejection period
-blood leaking back will reduce EDP

Question 16

Pressures during diastolic murmur (mitral valve stenosis)

Answer 16

-narrowing of mitral valve makes it hard for blood to flow from left atrium to left ventricle during diastole. Less blood enters therefore EDP decreases, SV decreases, and MAP decreases. Results in back up of blood into left atria (increasing pressure and hypertrophy occurs)
- turbulent flow also occurs