Prof. Sultan Ayoub MeoMBBS, M.Phil, Ph.D (Pak), PG Dip Med Ed, M Med Ed (Scotland)

FRCP (London), FRCP (Dublin), FRCP (Glasgow), FRCP (Edinburgh)Professor and Consultant, Department of Physiology,

College of Medicine, King Saud University, Riyadh, Saudi Arabia

HEART SOUNDSHEART SOUNDS

LECTURE OUTLI NES / OBJECTIVESLECTURE OUTLI NES / OBJECTIVES

List the major types of normal heart sounds

Understand the physiological basis for the

production of normal heart sounds

Understand the patho-physiological basis for the

production of heart murmurs

STUDENTS ABLE TO UNDERSTAND:

HEART SOUNDS

Heart sounds are made by the closure

of the heart valves and the acceleration

and deceleration or vibration of valves

due to blood flow in the cardiac

chambers.

First and second heart sounds are

normally heard during each cardiac

cycle.

One may hear a 3rd or 4th heart sound. Guyton and Hall

WHERE WE CAN HEAR THE HEART SOUNDS

Guyton and Hall

FIRST HEART SOUND (S1)FIRST HEART SOUND (S1)

First heart sound is produced due to the closure of Atrio-

ventricular valves (Tricuspid and Mitral).

It occurs at the beginning of the systole

Sounds like LUB

Frequency: 25-45 CPS (cycles per second) or Hz.

Soft when the heart rate is slow because ventricles are well

filled with blood and the leaflets of the A-V valves float

together before systole begins.

Time: 0.14 sec [Guyton]; 0.15 Sec [Ganongs] Guyton and HallGanongs

FIRST HEART SOUND (S1)FIRST HEART SOUND (S1)

First component due to turbulent rushing of blood towards A-V valves

2nd component occurs due to the closure of the A-V valves

3rd component is produced when semi-lunar valves open

4th component produced due to turbulent blood flow into large arteries

The mitral component heard at the apex beat area [left 5th intercostal

space at midclavicular line]

The tricuspid component is best heard in the 4th intercostal space at the

left sternal border

SECOND HEART SOUND (S2)SECOND HEART SOUND (S2)

This sound is produced by the vibration associated with the closure of the semilunar valves (aortic and pulmonary) at the end of ventricular systole.

ECG relationship: The second heart sound occur soon after the T-wave of ECG.

Duration: 0. 11 sec [Guyton]; 0.12 [Ganong]. Frequency: 50 Hz or CPS. This sound is sharp and loud and described as “DUB.” Two sub components Pulmonary component heard at the level of 2nd left

intercostal space. Aortic component is heard at the level of the 2nd right

interscostal space near the right border of the sternum.

Guyton and Hall; Ganong

SECOND HEART SOUND (S2)SECOND HEART SOUND (S2)

The S2 duration is 0.11 Sec and S1 is about 0.14 second

The reason for the shorter S2 is that semilunar valves are more tight

than A-V valves, so they vibrate for a shorter time than A-V valve

The S2 has higher frequency than the S1 for two reasons:

1. The tautness of the semilunar valves than A-V valves

2. The greater elastic coefficient of the taut arterial walls that

provide the principal vibrating chambers for the S2.

Second heart sound has physiological inspiratory splitting

Guyton and HallChest wall expands during inspiration

Intrathoracic pressure becomes more negative to form a vacuum

Venous return from the body to the right heart increases, venous return from the lungs to the left heart decreases

THIRD HEART SOUND (S3)THIRD HEART SOUND (S3)

Occurs at the beginning of middle third of Diastole

Cause of third heart sound

Rush of blood from Atria to Ventricle during rapid

filling phase of Cardiac Cycle.

It causes vibration in the blood

Frequency:20-30 Htz

Time: 0.1 sec

FOURTH HEART SOUND (S4)FOURTH HEART SOUND (S4)OR ATRIAL SOUNDOR ATRIAL SOUND

Occurs at the last one third of Diastole [Just before S1]

Produced due to Atrial contraction which causes rapid flow of

blood from Atria to Ventricle and vibration in the blood.

Frequency: 20 cycles / sec or less [Htz]

Third and Fourth heart sound are low pitched sounds

therefore not easily audible normally with stethoscope

S3 may be heard in children and young adults

Heart Sound Occurs during: Associated with:

S1Isovolumetric contraction

Closure of mitral and tricuspid valves

S2 Isovolumetric relaxationClosure of aortic and pulmonic valves

S3 Early ventricular fillingNormal in children; in adults, associated with ventricular dilation (e.g. ventricular systolic failure)

S4 Atrial contractionAssociated with stiff, low compliant ventricle (e.g., ventricular hypertrophy

SUMMARY OF HEART SOUND SUMMARY OF HEART SOUND

VS VD

HEART SOUNDS: ASSOCIATION WITH CARDIAC CYCLE

HEART SOUNDS

0.3Sec. 0.5 sec.

1 st Heart Sound 2 nd Heart Sound 3 rd Heart Sound 4 th Heart Sound

AS – Atrial Systole; AD – Atrial Diastole ; VS – Ventricular systole; VD – Ventricular diastole

CARDIAC CYCLE: ASSOCIATION WITH HEART SOUNDS

Guyton and Hall

CARDIAC CYCLE: ASSOCIATION WITH

HEART SOUNDS

Ganongs

MURMURS

abnormal heart sounds, produced with excessive degree of

turbulence of blood flow in the heart chambers. Murmurs occurs

when there is an abnormality of the cardiac valves (stenosis and

incompetence).

Murmurs of aortic stenosis and mitral regurgitation occur only

during systole.

Murmurs of aortic regurgitation and mitral stenosis occur only

during diastole. Systolic types: Pan systolic murmurs, Ejection murmurs,Late systolic murmurs.Diastolic types: Early diastolic murmurs, Mid diastolic

murmurs.

HEART MURMURS HEART MURMURS

Heart Murmurs

Valve Abnormality Timing of Murmur

Aortic or pulmonary Stenosis Systolic

  Insufficiency Diastolic

Mitral or tricuspid Stenosis Diastolic

  Insufficiency Systolic

Ganong

MURMURS

HEART SOUNDS

Guyton and Hall

SYSTOLIC MURMURS

Systolic murmurs: Majority of murmurs are systolic, usually

early in systole and disturb the end of S1. S1 often appears

slurred, Physicians focus on the end of S1 for soft systolic

murmurs.

Holo systolic murmur: refers to a systolic murmur that begins

during or immediately after S1 and ends with the onset of S2.

Mainly heard with mitral valve insufficiency.

Pansystolic murmur: Systolic murmur begins during or

immediately after S1 and continues into and complicate S2Guyton and Hall

DIASTOLIC MURMURS

Diastolic murmurs: Very rare, low frequency, low intensity

and best identified with the bell of the stethoscope

Continuous murmurs: Common, but less than systolic,

typically associated with a PDA and also arteriovenous fistulas.

Systolic murmurs of Aortic Stenosis:

Blood ejected from left ventricle through small fibrous

opening of the aortic valve.

Because of resistance to ejection the pressure in the ventricle

increase while the pressure in the aorta is still normal.

Nozzle effect is created during systole, with blood jetting at

tremendous velocity through the small opening of the valve.

This causes severe turbulence of blood in the root of the aorta

and causes intense vibration, loud murmur occurs during systole

SYSTOLIC MURMURS [AORTIC STENOSIS]

Guyton and Hall

SYSTOLIC MURMURS [AORTIC STENOSIS]

Systolic murmurs of Aortic Stenosis [Continued]:

Transmitted throughout the superior thoracic aorta and even

into the large arteries of the neck

This sound is harsh

In severe stenosis sound may be so loud that it can be heard

several feet away from the patient.

Sound vibrations often felt with the hand on the upper chest

and lower neck, a phenomenon known as a “thrill.”

Guyton and Hall

SYSTOLIC MURMURS: MITRAL REGUGITATION

Systolic Murmur of Mitral Regurgitation.

In mitral regurgitation blood flows backward through the

mitral valve into the left atrium during systole.

This also causes a high-frequency “blowing,” swishing

sound similar to that of aortic regurgitation but occurring

during systole rather than diastole.

The sound of mitral regurgitation is transmitted to the chest

wall mainly through the left ventricle to the apex of the heart.

Guyton and Hall

DIASTOLIC MURMURS [MITRAL STENOSIS]

Diastolic Murmur of Mitral StenosisDiastolic Murmur of Mitral Stenosis:

In mitral stenosis, blood passes with difficulty through the

stenosed mitral valve from the left atrium into the left ventricle.

Because pressure in the left atrium rises above 30 mm Hg,

large pressure differential forcing blood from left atrium into

the left ventricle does not develop. Consequently, the abnormal

sounds heard in mitral stenosis usually weak and very low

Guyton and Hall

DIASTOLIC MURMURS [AORTIC REGUGITATION]

Diastolic Murmur of Aortic Regurgitation. Diastolic Murmur of Aortic Regurgitation.

In aortic regurgitation no abnormal sound is heard during

systole, but during diastole

Blood flows backward from the high-pressure aorta into the

left ventricle causing a “blowing” murmur of high pitch with a

swishing quality heard maximally over the left ventricle.

This murmur results from turbulence of blood jetting

backward into the blood already in the low-pressure diastolic left

ventricle. Guyton and Hall

HEART MURMURS CAUSED BY HEART MURMURS CAUSED BY VALVULAR LESIONSVALVULAR LESIONS

Machinery murmur of patent ductus arteriosis [PDA]

In PDA blood flows from the aorta to the pulmonary artery

Murmur during systole and diastole.

The murmurs during systole is much more tense than in

diastole because the pressure in aorta is higher during systole

than diastole.

THANK YOU THANK YOU

College of Medicine, King Khalid University College of Medicine, King Khalid University Hospital, King Saud University, Riyadh, Hospital, King Saud University, Riyadh,

Saudi ArabiaSaudi Arabia