Cardiac murmur is the abnormal heart sound.
It is also called cardiac bruit.
Cardiac murmur is mainly heard by stethoscope, along with the normal heart sounds.
CAUSES OF MURMUR
-It is produced because of change in the pattern of blood flow.
-Normally, the blood flows in streamline through the heart and blood vessels.
-However, during abnormal conditions like valvular diseases, the flow of blood becomes turbulent.
-It produces the cardiac murmur.
-Murmur is produced because of the following like valvular diseases, septal defects and vascular defects
Valvular diseases are of two types:
-Stenosis means narrowing of heart valve.
-The flow of blood is rapid with turbulence through the narrow orifice of the valve, resulting in murmur.
-Incompetence refers to weakening of the heart valve.
– Due to the weakness of the value , it cannot close properly.
-Which causes back flow of blood, resulting in turbulence.
-This disease is also called valvular insufficiency.
CLASSIFICATION OF MURMUR
Cardiac murmur is classified into three types:
A. Systolic murmur
B. Diastolic murmur
C. Continuous murmur.
During systole the murmur produced is know as SYSTOLIC MURMUR. It is produced in the following conditions:
1. Incompetence of Atrioventricular Valves
-When the atrioventricular valves become weak, these valves cannot close completely.
-What it causes is like regurgitation of blood from ventricles to the atria during ventricular systole, producing the murmur.
– The sound is harsh with high frequency.
2. Stenosis of Semilunar Valves
-During the stenosis of aortic valve, the pressure of the left ventricle rises to 300 mm Hg during systole.
-It causes a greater turbulence in the flow of the blood.
-In severe conditions, the sound is heard even a few feet away from the affected person.
– The sound is harsh and loud .
3. Murmur due to Anemia
-A systolic murmur is mainly heard in severe anemia because of reduced viscosity and accelerated flow of blood.
4. Septal Defect
-Blood flows from left ventricle to right ventricle during systole, during the interventricular septal defect.
-It produces a systolic murmur.
– Septal defect is a rare disorder.
5. Coarctation of Aorta
-It is a congenital disorder, characterized by the narrowing of a part of systemic aorta.
-A loud murmur is produced during systole and it is heard in the earlier part of diastole also.
-It is the murmur that is produced during diastole.
-It is produced in the following conditions:
1. Stenosis of Atrioventricular Valves
When the atrioventricular valves become narrow, the turbulence of blood flow occurs during diastole, i.e. when blood enters the ventricles from atria.
-At mitral area the stenosis of the mitral valve is heard clearly.
-At tricuspid area the stenosis of the tricuspid valve is heard clearly
-It is a weak sound with low frequency.
-Sometimes, murmur cause by mitral stenosis cannot be heard by stethoscope, because of low frequency.
-But it can be felt as a mild thrill mainly over mitral area of the chest.
2. Incompetence of Semilunar Valves
-Murmur is mainly produced during the regurgitation of blood from aorta into the ventricle, through incompetent semilunar valve during diastole.
– It sounds like a blowing sound; with low frequency.
-Continuous murmur is the murmur that is heard in conditions such as patent ductus arteriosus.
-A continuous murmur is heard in this condition.
-However, intensity of the sound is more during systole and less during diastole.
-Because of this, it is also known as machinery murmur.
-It is a harsh blowing sound and is heard best in the pulmonary area. The murmur is heard 1 year after birth.
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