Cardiac Auscultation I

Question 1

What side of the stethoscope do you listen to low frequency sounds with? High frequency sounds?

Answer 1

Low frequency (S3, S4) = bell
High frequency (S1, S2, opening snaps, ejection clicks) = diaphragm

Question 2

What are 3 conditions which influence the intensity of S1?

Answer 2

1. degree of separation between AV valve leaflets at the onset of ventricular contraction (greater separation = louder sound)
2. pliability of valve leaflets (calcified and less pliable = softer S1)
3. contractility of ventricle (increased inotrophy = louder heart sounds)

Question 3

What are 3 conditions asso/ w/ loud S1?

Answer 3

1. Short PR interval (eg Wolff-Parkinson-White) caused by early depol of LV b/c LV contracts while mitral is open)
2. Mitral stenosis if valve is pliable still
3. Hypercontractile states (exercise, hyperthyroidism)

Question 4

What are 3 conditions asso/ w/ soft S1?

Answer 4

1. Long PR interval (eg first degree AV block)
2. Mitral stenosis if the valve is calcified
3. Acute aortic regurg.

Question 5

When can audible splitting of S1 be appreciated?

Answer 5

In pts with conduction abnormalities such as RBBB or atrial septal defects

Question 6

Why does splitting of S2 occur during inspiration?

Answer 6

Inspiration causes greater negative pressure in the thoracic cavity. This greater negative pressure means more venous return, more venous return = longer contraction period of RV compared to LV, so the pulm valve closes later. Also the impedance of the vascular pulmonary bed decreases during inspiration

Question 7

What is the hangout interval?

Answer 7

It is the interval between the anacrotic notch and the pulmonary incisura; represents the split of the S2 sound

Question 8

Why is there general splitting of S2?

Answer 8

1. RV systolic ejection begins before left
2. Duration of RV systolic ejection is longer than LV ejection
3. Prolonged interval between anacrotic notch and the pulmonary incisura, leading to a hangout period

Question 9

What 3 general conditions can cause abnormal S2 splitting?

Answer 9

1. Abnormalities in cardiac conduction
2. Changes in duration of ventricular ejection
3. Changes in pulmonary vascular impedance

Question 10

What are electromechanical changes in the heart that can cause an abnormal splitting of S2?

Answer 10

LBBB, RBBB, ventricular paced beats

Question 11

What are the possible causes of changes in the duration of ventricular ejection that can lead to abnormal splitting of S2?

Answer 11

Aortic and pulmonary stenosis or mitral and tricuspid regurgitation

Question 12

What are the causes of changes in pulmonary vascular impedance that can lead to abnormal splitting of S2?

Answer 12

Atrial septal defects or pulmonary hypertension

Question 13

What is wide physiological splitting of S2?

Answer 13

Audible splitting of S2 heard in both inspiration and expiration

Question 14

What causes wide physiological splitting of S2 (2 categories of reasons, and then 2

Answer 14

Due to late closure of pulmonic valve or early closure of aortic valve, thus:

• delayed closure of PV can occur with RBBB, pulmonary stenosis, and atrial septal defects
• early closure of AV can occur with severe mitral regurg and ventricular septal defects

Question 15

What is reversed or paradoxical splitting of S2?

Answer 15

It is when the S2 splits are narrow during inspiration and wide during expiration, opposite of what happens physiologically.

Question 16

What causes reversed splitting of S2?

Answer 16

Associated with late closure of the aortic valve or early closure of the pulmonic valve (delayed closure of aortic valve occurs with LBBB and aortic stenosis)

Question 17

What is narrow splitting of S2?

Answer 17

Inspiratory splitting is absent

Question 18

What causes narrow splitting of S2?

Answer 18

Either early closure of pulmonic valve or late closure of aortic valve:

1. Early PV closure occurs with tricuspid regurg or pulm hypertension
2. Late AV closure occurs with aortic stenosis or decreased peripheral vascular resistance (e.g. peripheral vascular shunts or a patent ductus arteriosus)

Question 19

What are 4 diastolic filling sounds?

Answer 19

S3, S4, opening snap, and pericardial knock

Question 20

What is S3? What could cause it in adults?

Answer 20

Rapid diastolic filling of LV. In adults may be caused by congestive heart failure or mitral/tricuspid valve regurg

Question 21

What is S4?

Answer 21

Low frequency diastolic sound due to a noncompliant left ventricle late in diastole. Can be present in pts with hypertension, hypertrophic cardiomyopathy, or acute myocardial ischemia

Question 22

What is a gallop?

Answer 22

S3 and S4 in rapid succession. Can be right or left sided in origin.

Question 23

What is a pericardial knock?

Answer 23

Sharp, early diastolic sound associated with constrictive pericarditis

Question 24

What is an opening snap?

Answer 24

A sound associated with the opening of the mitral or tricuspid valves when they are pliable but more restricted. Heard in patients with rheumatic or congenital mitral valve disease

Question 25

What are the two categories or systolic ejection sounds?

Answer 25

Valvular clicks: associated with deformed aortic or pulmonic valves
Vascular/root sounds: sounds that occur because of forceful ejection of blood into tensed great vessels

Question 26

How can pulmonic and aortic ejection sounds be distinguished?

Answer 26

Pulmonic ejection sounds vary with inspiration and the RV preload; with inspiration, the greater preload means the sound is much softer, because the flow into the RV slightly opens the pulmonic valve before ventricular systole so the sound is not as harsh. With expiration, the pulmonic valve opens rapidly from a fully closed spot

Question 27

What is mitral valve prolapse?

Answer 27

Abnormal thickening of the mitral valve that makes it too long for the MV annulus. Associated with an MV click which is a high frequency systolic sound

Question 28

How can posture affect the timing of the mitral valve prolapse click?

Answer 28

When supine, the LV preload is greater and thus the MVP click occurs later because the annulus stretches further and reduces the mismatch of the annulus and the valve. When standing up, preload decreases, the annulus doesn’t stretch out, and the click happens earlier. Later = closer to S2, earlier = closer to S1.