Heart Valves and Heart Sounds Prof.Dr. Ümmühan İşoğlu-Alkaç İ.Ü. İstanbul Tıp Fakültesi Fizyoloji Anabilim Dalı alkac@istanbul.edu.tr YU Medical Faculty, 21.10.2013

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