Prof.Dr. Ümmühan İşoğlu-Alkaç

İ.Ü. İstanbul Tıp Fakültesi Fizyoloji Anabilim Dalıalkac@istanbul.edu.tr

YU Medical Faculty, 21.10.2013

Heart Valves

and Heart Sounds

Heart Valves and

Heart Sounds

Heart Valves

• Heart valves ensure unidirectional blood flow through

the heart

• Atrioventricular (AV) valves lie between the atria and

the ventricles

• AV valves prevent backflow into the atria when

ventricles contract

• Chordae tendineae anchor AV valves to papillary

muscles

Heart Valves

Atrioventricular Valve Function

Heart Valves

• Aortic semilunar valve lies between the left

ventricle and the aorta

• Pulmonary semilunar valve lies between the right

ventricle and pulmonary trunk

• Semilunar valves prevent backflow of blood into the

ventricles

Heart Valves

Semilunar Valve Function

Normal Heart Sounds

• Closing of the valves causes audible sounds

• No audible sounds occur when the valves open

• “Lub” is associated with closure of AV valves at

the beginning of the systole and

• “Dub” is associated with closure of semilunar

valves at the end of systole

• The lub sound is called the first heart sound

• The dub sound is called the second heart sound

http://depts.washington.edu/physdx/heart/demo.html

Causes of the First and Second Sounds

• First heart sound: Vibration of taut valves

immediately after closure, vibration of the adjacent

heart walls and major vessels around the heart

• Auscultation of heart sounds by stethescope

• Second heart sound: when the semilunar valves

close, they bulge backward toward the ventricles

• The vibration occurring in the arterial walls are then

transmitted mainly along the arteries

Duration and Pitch of the Heart Sounds

• Duration of the first heart sound is about 0.14 second

• Second heart sound lasts about 0.11 second

• A-V valves vibrate a little longer

• The second heart sound has a higher frequency

because of two factors:

– Tautness of the semilunar valves in comparison with

much less taut A-V valves

– The greater elastic coefficient of the taut arterial walls

that provide the principal vibrating chambers for the

second sound

Third and Fourth Heart Sounds

• Third Heart Sound: occasionally a third rumbling

heart sound is heard at the beginning of the middle

third of diastole

• This is caused by oscillation of blood back and forth

between the walls of ventricles

• Atrial Heart sound (the fourth sound): An atrial heart

sound can sometimes be heard in the

phonocardiogram

• It can almost never be heard with stethescope

• This sound occurs when the atria contract

Chest Surface Areas for Auscultation

Two audible heart sounds: They are termed the first (S1) and second (S2).

They sound like “lub dup”.

The first is low pitched and the second is high.

Sounds come from turbulent flow around the valve cusps and vibration of the heart structures

Two more sub-audible heart sounds are present, the third (S3) and fourth (S4) heart sounds.

Too faint to be heard but can be seen in a phonocardiogram

If S3 or S4 are audible it is called a gallop.

S3 results from rapid filling of the ventricle during diastole.

It is sometimes heard in normal children and in some patients with heart failure

S4 (the atrial sound) is due to atrial systole

Rheumatic Valvular Lesions

• The greatest number of valvular lesions result from rheumatic

fever

• It is an autoimmune disease, usually initiated by streptococcal

toxin

• Heart valves are likely to be damaged or destroyed

• Lesions become scar tissue, fusing the portions of adjacent

valve leaflets.

• Stenosis: valve leaflets adhere to one another that blood cannot

flow thorugh it normally

• Regurgitation: when the valve edges are so destroyed by scar

tissue that they cannot close during ventricular contraction

• Stenosis usually coexists with some regurgitation or vice versa

Heart Murmurs Caused by Valvular Lesions

• Abnormal heart sounds are known as murmurs

• Systolic murmur of aortic stenosis

– Nozzle effect and

– Severe turbulence of blood in the root of aorta

• Diastolic murmur of aortic regurtigation

– No abnormal sound is heard during systole, but

diastole

– Turbulence of blood jetting backward into the low-

pressure diastolic left ventricle

Heart Murmurs Caused by Valvular Lesions

• Systolic murmur of mitral regurgitation

– Blood flows backward thorugh the mitral valve into the left

atrium during systole

– Causes high-frequency sound

– Occurs during systole

– Felt strongly at the left atrium (apex of the heart)

• Diastolic murmur of mitral stenosis

– Stenosed mitral valve

– Abnormal sounds heard in mitral stenosis are weak

– Pressure in the left atrium rarely rises above 30 mmHg

Abnormal Circulatory Dynamics in Valvular Heart Disease

• In aortic stenosis, contracting left ventricle fails to empty

adequately

• In aortic regurgitation, blood flows backward into the ventricle

• In either case, stroke volume is reduced

• Hypertrophy of the left ventricle:

• In both aortic stenosis and regurgigation, left ventricular

musculature hypertrophies because of increased workload

• Increase in blood volume:

– An initial slight decrease in arterial pressure

– Peripheral circulatory reflexes – decreased renal output

Abnormal Circulatory Dynamics in Congenital Heart Disease

• There are three major types of congenital anomalies of the

heart and its associated vessels:

• Stenosis

– Congenital aortic valve stenosis

– Aort coarctation

• Left to right shunt (patent ductus arteriosus)

• Right to left shunt (teratology of fallot)

Patent Ductus Arteriosus

• Pulmonary artery blood flows through a special artery

(called ductus arteriosus) present in the fetus that

connects pulmonary artery with the aorta

• This allows recirculation of blood through the systemic

arteries of fetus without the blood going through the lungs

• Closure of the ductus arteriosus after birth

• Incidence is about 1 in 5500 births

• Dynamics of the circulation with a persistent patent ductus

Patent Ductus Arteriosus

• Symptoms become severe until the child grows older

• Heart sounds: machinery murmur

– A blowing murmur is heard in the pulmonary artery

area of chest

– Surgical treatment of patent ductus arteriosus

Patent Ductus Arteriosus

Teratology of Fallot (a right to left shunt)

• It is the most common cause of “blue baby”

• Most of the blood bypasses the lungs, so aortic blood is mainly

unoxygenated venous blood

– Aorta originates from the right ventricle rather than the left, receiving

blood from both ventricles

– Pulmonary artery is stenosed

– Blood from the LV flows either through a ventricular septal hole into the

RV or directly into the aorta

– Right ventricular hyperthrophy

• Abnormal circulatory dynamics: about 75% of blood is

unoxygenated (venous blood)

Teratology of Fallot (a right to left shunt)

• Diagnosis

– Baby’s skin is cyanotic (blue), Measurement of high blood pressure

in the right ventricle

– Radiological findings (enlarged RV), Angiograms

• Surgical treatment of pulmonary stenosis and closure of

septal defect

Phonocardiogram