Murmurs

1. MURMURS
MBS 310
@
CBU SCHOOL OF MEDICINE

2. A heart murmur is an abnormal sound i.e. a sound that is not
normally present .
They are produced when the normal silent (-laminar) blood flow is
replaced by a turbulent (noisy) blood flow
This occurs when the blood velocity exceeds a certain limit
The blood velocity increases after an area of partial obstruction in a
blood vessel and also as it passes through stenotic or insufficient heart
valves.
A stenotic valve is a stiff narrowed valve that does not open
completely
An insufficient (or incompetent) valve is a valve that does not close
completely

3. TYPES OF HEART MURMURS
(1) Systolic murmurs :
These occur during the ventricular systolic period (i.e. between the
first and second sounds)
They may occur without heart disease (e.g. in anemia, fevers and
exercise) or as a result of valvular disorders produced by diseases
(specially rheumatic fever) or congenital abnormalities.

4. The valvular disorders that produce systolic murmurs are either :
(a) Stenosis of one of the semilunar valves
(b) Incompetence of one of the AV valves: This may occur due to
scarring of the valve cusps or a disorder in the papillary muscle-chordae
tendinenae system.
In these leaky valves blood regurgitation occurs toward the atria
during ventricular systole resulting in the abnormal sound
(c) Ventricular Septal Defect (VSD) (a congenital abnormality)

5. (2) Diastolic murmurs :
These occur during the ventricular diastolic period (i.e. between the
second sound and the next first sound) as a result of either of the
following valvular disorders :
(a) Stenosis of one of the AV valves (e.g. due to rheumatic rever)
(b) Incompetence of one of the semilunar valves :
In aortic incompetence (which is commonly due to syphilis), blood
regurgitates from the aorta into the left ventricle during ventricular
diastole resulting in a murmur as well as reduction in the diastolic
pressure
The systolic pressure also increases (because the left ventricle will
eject a larger volume of blood than normal) so the pulse pressure also
increases

6. (3) Continuous murmurs
(during systole & diastolc) e.g. in patent ductus arteriosus (since the
aortic B.P. is always higher than the pulmonary arterial B.P.) and also in
arteriovenous fistulas

7. Heart Murmurs
Valve Abnormality Timing of Murmur
Aortic or pulmonary Stenosis Systolic
Insufficiency Diastolic
Mitral or tricuspid Stenosis Diastolic
Insufficiency Systolic

8. MURMURS

10. 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
increases 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
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.”

11. SYSTOLIC MURMURS OF MITRIAL 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.

12. SYSTOLIC MURMURS OF MITRIAL STENOSIS
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 is usually weak and very low
In mitral stenosis, blood passes with difficulty through the stenosed
mitral valve from the left atrium into the left ventricle.

13. DIASTOLIC MURMURS OF AORTIC REGUGITATION
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.