Heart Sounds During each cardiac cycle, 4

heart sounds are produced.

These can be recorded in phonocardiogram.

By auscultation we can hear/ auscultate, 1st & 2nd heart sounds & sometimes 3rd as well.

But 4th is Atrial heart sound, which is never auscultated normally.

1st & 2nd heart sounds are called as CLASSICAL HEART SOUNDS (as they are usually auscultated in normal subjects).

4 Auscultatory areas Pulmonary Area: Left 2nd

intercostal space, close to sternal border.

Aortic Area: Right 2nd intercostal space, close to sternal border.

Mitral Area: left 5th intercostal space in the midclavicular line, 9 cm away from the sternal border.

Tricuspid Area: 4th left intercostal space close to sternal border.

4 basic factors affecting Heart Sounds:

Acceleration of blood: Sudden flow.

Deceleration: Sudden stoppage of blood flow.

Turbulance in the flow of blood.

Thickness of chest wall.

1st Heart Sound

Characteristics:

Long, soft, low pitched. (heard as LUBB)

Frequency: 30 – 50 cycles /sec.

Duration: 0.14 sec

1st Heart Sound

CAUSES: Vibrations due to closure

of AV valves, at the beginning of ventricular systole.

Vibrations in ventricles & large vessels when ventricular muscle contracts.

Vibrations when blood starts ejecting into large artery.

Physiological Splitting of 1st heart sound

Mechanism:

Tricuspid valve may close earlier than mitral.

Intensity of 1st heart sound

Depends on:

Force of ventricular systole.

Rate of increase in ventricular pressure, during isovolumic contraction phase.

2nd Heart Sound

Characteristics:

Short, sharp, high pitched (heard as DUBB)

Frequency: 50 – 200 cycles / sec.

Duration: 0.11 sec

2nd Heart Sound:

Minor causes:

When blood flows from ventricle to large arteries, there may be turbulance.

Splitting of 2nd Heart Sound:

PHYSIOLOGICAL

Increases or Widens during inspiration (0.5 sec) & decreases during expiration (0.02 sec or disappear).

Cause of splitting:

During inspiration venous return increases more blood returns to right atrium right ventricle more ejection delayed closure of pulmonary valve.

Reverse occurs in expiration.

PATHOLOGICAL

In bundle branch block, mainly right bundle branch block.

Intensity of pulmonary component of 2nd heart sound is increased in pulmonary hypertension.

Intensity of aortic component is increased in systemic (aortic) hypertension

3rd Heart Sound:

Cause: Vibrations produced in

ventricular wall during Rapid

Inflow Phase.

Prominent sometimes in children.

Can be made prominent by increasing venous return:

i) exercise.

ii) lying position.

Low frequency sound.

Duration: 0.04 sec.

Best heard at: Apex of heart, in 5th intercostal space (mid-clavicular line).

4th Heart Sound:

Not normally auscultated but recorded in phonocardiogram.

Low frequency, low intensity sound.

Produced just before 1st heart sound.

Also called ATRIAL HEART SOUND.

Cause: Vibrations of ventricular wall, due

to impact of blood pumped from the atrium into ventricle during Atrial Systole.

Diseases: In CCF, 4th Heart Sound is

auscultated.

MURMURS:

These are abnormal heart sounds.

Produced when:

1. Valvular stenosis.

2. Valvular incompetence.

3. Hyperdynamic circulation: Hyperthyroidism, severe anemia (hemic

murmurs)

MURMURS

Systolic murmurs: Aortic stenosis

Mitral regurgitation

Diastolic murmurs: Aortic regurgitation

Mitral stenosis

Murmur throughout cardiac cycle: Patent ductus arteriosus

(PDA)- its murmur is also called as machinary murmur.