Transcript second heart sound

HEART SOUNDS
Prof. Sultan Ayoub Meo
MBBS, 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
LECTURE OUTLI NES / OBJECTIVES
STUDENTS ABLE TO UNDERSTAND:
 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
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 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 Hall
Ganongs
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)
 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)
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
Chest wall expands during inspiration
Intrathoracic pressure becomes more negative to form a vacuum
Guyton and Hall
Venous return from the body to the right heart increases, venous return from the lungs to the left heart decreases
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)
OR 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
SUMMARY OF HEART SOUND
Heart Sound Occurs during:
Associated with:
S1
Isovolumetric contraction
Closure of mitral and tricuspid
valves
S2
Isovolumetric relaxation
Closure of aortic and pulmonic
valves
Early ventricular filling
Normal in children; in adults,
associated with ventricular dilation
(e.g. ventricular systolic failure)
Atrial contraction
Associated with stiff, low
compliant ventricle (e.g.,
ventricular hypertrophy
S3
S4
HEART SOUNDS: ASSOCIATION WITH
CARDIAC CYCLE
VS
VD
0.3Sec.
0.5 sec.
1 st Heart Sound
2 nd Heart Sound
3 rd Heart Sound
4 th Heart Sound
HEART SOUNDS
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
Valve
Abnormality
Timing of Murmur
Aortic or pulmonary
Stenosis
Systolic
Insufficiency
Diastolic
Stenosis
Diastolic
Insufficiency
Systolic
Mitral or tricuspid
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 S2
Guyton 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 [AORTIC
STENOSIS]
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
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
STENOSIS]
MURMURS
[MITRAL
Diastolic 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
REGUGITATION]
[AORTIC
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
VALVULAR 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
College of Medicine, King Khalid University
Hospital, King Saud University, Riyadh,
Saudi Arabia