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Auscultation of heart. Methodic, rules and order of auscultation of heart. Tones of heart. Characteristic of tones of heart with healthy persons.

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Auscultation of the heart

Cardiac auscultation is systematic listening to heart sounds, extra sounds, and murmurs using a stethoscope. It assesses:
  • Heart rate and rhythm
  • First and second heart sounds: S1 and S2
  • Physiological splitting of S2
  • Additional sounds: S3, S4, clicks, snaps
  • Murmurs and pericardial friction rub
The normal cycle produces the familiar “lub-dub”: S1 is related to atrioventricular-valve closure at the onset of systole, and S2 to semilunar-valve closure at the end of systole. Guyton and Hall Textbook of Medical Physiology, p. 288.

Preparation and general rules

  1. Environment
    • Quiet, warm room.
    • Explain the procedure and expose the precordium adequately while maintaining privacy.
    • The patient should be relaxed. Shivering, anxiety, tachycardia, and noise make interpretation difficult.
  2. Stethoscope
    • Warm the chest piece before contact.
    • Use the diaphragm for high-pitched sounds:
      • S1 and S2
      • Most systolic murmurs
      • Aortic regurgitation murmur
      • Pericardial rub
    • Use the bell lightly for low-pitched sounds:
      • S3 and S4
      • Mitral stenosis rumble
  3. Patient positions
    • Start supine or semi-recumbent at 30 to 45 degrees.
    • Then examine in:
      • Left lateral decubitus position: best for low-frequency apical sounds, especially S3, S4, and mitral stenosis murmur.
      • Sitting forward, fully exhaling and briefly holding expiration: best for aortic regurgitation and other left-sided basal murmurs.
  4. Technique
    • Place the stethoscope directly on bare skin, not over clothing.
    • Listen at each area for at least several cardiac cycles.
    • Compare sounds during quiet inspiration and expiration.
    • Identify S1 first, then S2. S1 occurs just after the carotid upstroke and marks the beginning of systole.

Standard order of auscultation

The listening areas do not exactly overlie the valves. They are locations where sound from each valve is transmitted best.
AreaLocationBest assesses
Aortic areaRight 2nd intercostal space, close to sternumAortic valve
Pulmonic areaLeft 2nd intercostal space, close to sternumPulmonary valve
Erb’s pointLeft 3rd intercostal space, parasternalS2, aortic regurgitation
Tricuspid areaLeft lower sternal border, 4th or 5th intercostal spaceTricuspid valve
Mitral or apical areaCardiac apex, usually left 5th intercostal space at or just medial to midclavicular lineMitral valve
A conventional sequence is:
Aortic → Pulmonic → Erb’s point → Tricuspid → Mitral (apex).
At every site, assess:
  1. Rate
  2. Rhythm
  3. S1 and S2 intensity and quality
  4. Splitting of S2
  5. Extra sounds
  6. Murmurs, including timing, site of maximal intensity, radiation, pitch, quality, and response to respiration or position

Normal heart sounds

First heart sound: S1

Cause

S1 is generated mainly by closure and tension of the mitral and tricuspid valves at the onset of ventricular systole. Mitral closure normally precedes tricuspid closure slightly.

Timing

  • Occurs at the beginning of systole
  • Follows the QRS complex
  • Coincides approximately with the carotid pulse upstroke
  • It is the first sound in the sequence: S1 - systole - S2 - diastole

Normal characteristics

  • Usually a low-pitched, longer “lub” sound.
  • Best heard with the diaphragm.
  • Best appreciated at the apex and lower left sternal border.
  • Normally louder at the apex than at the base.
  • It may show minimal physiological splitting, but a single S1 is usually heard clinically.

Normal variation

S1 may be louder with:
  • Thin chest wall
  • Tachycardia
  • Increased sympathetic tone or exercise
S1 may be softer with:
  • Obesity
  • Emphysema
  • Low cardiac output
These variations alone do not establish disease.

Second heart sound: S2

Cause

S2 results from closure of the aortic valve (A2) and pulmonary valve (P2) at the end of ventricular systole and beginning of diastole.

Timing

  • Marks the end of systole and the start of diastole.
  • Shorter and sharper than S1.
  • Heard as the “dub” in “lub-dub.”

Normal characteristics

  • Relatively high-pitched and brief.
  • Best heard with the diaphragm.
  • Loudest at the base of the heart:
    • A2 at right upper sternal border
    • P2 at left upper sternal border
  • Usually more prominent than S1 at the base.

Physiological splitting of S2

Normally, A2 occurs slightly before P2. During inspiration, increased venous return to the right ventricle prolongs right ventricular ejection, delaying P2. Therefore:
  • Expiration: S2 often sounds single: S1 - S2
  • Inspiration: S2 may split: S1 - A2 - P2
This is normal physiological splitting and is typically most audible in the pulmonic area. The MSD cardiac auscultation review describes the normal inspiratory delay of P2.

Third heart sound: S3

Timing and mechanism

  • Occurs in early diastole, shortly after S2.
  • Produced during rapid passive ventricular filling.

Normal status

  • May be normal in:
    • Children
    • Adolescents
    • Young adults
    • Pregnancy
    • Well-trained athletes
  • In adults older than about 40 years, an S3 often suggests increased ventricular filling pressure or volume overload, such as heart failure.

Description

  • Low-pitched.
  • Best heard with the bell at the apex in the left lateral position.
  • Rhythm: S1 - S2 - S3, sometimes described as a ventricular gallop.

Fourth heart sound: S4

Timing and mechanism

  • Occurs in late diastole, immediately before S1.
  • Caused by atrial contraction against a stiff, noncompliant ventricle.

Normal status

  • Generally not a normal finding in healthy adults.
  • It cannot occur in atrial fibrillation because effective atrial contraction is absent.

Description

  • Low-pitched.
  • Best heard with the bell at the apex, especially in left lateral decubitus position.
  • Rhythm: S4 - S1 - S2, called an atrial gallop.

Normal findings in a healthy person

A healthy adult usually has:
  • Regular rate and rhythm
  • Clear S1 and S2
  • S1 louder at the apex
  • S2 louder at the base
  • No persistent abnormal splitting of S2
  • A soft physiological split of S2 during inspiration may be present
  • No S3 or S4 in most middle-aged and older adults
  • No clicks, opening snaps, rubs, or murmurs
A soft, short systolic flow murmur can occasionally occur in healthy people, especially with increased flow states, but it should not have pathological features such as a thrill, diastolic timing, or significant radiation.

Practical one-line sequence

Listen over all five valve areas with diaphragm, then bell; assess S1, S2, splitting, extra sounds and murmurs; repeat at the apex in left lateral position and at the base while the patient sits forward in expiration.
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