Abnormal heart sounds are called Murmurs. Murmurs are of various types. Here we will discuss common types of cardiac murmurs.
Types of cardiac murmurs.Murmurs are grossly divided as systolic and diasystolic murmurs.
Murmurs heard between first heart sound and second heart sound are called systolic murmurs and murmurs heard between second heart sound and first heart sound are called diasystolic murmurs.
Now systolic murmurs are further divided into.
1. Mid systolic murmurs
2. Pan-systolic murmurs
3. Late systolic murmurs
and diasystolic murmurs are further divided into;
1. Mid-diasystolic murmurs
2. Early diasystolic murmurs
Murmurs can be present in both systolic and diasystolic phase of heart beat.
Systolic Murmurs:Mid Systolic Murmurs:
narrowing aortic valve is called aortic stenosis. When left ventricle contracts, it forces blood into aorta. Forced and fast movement of blood through aorta produces harsh sound which can be heard as murmur. It is best heard in aortic area.
When right ventricle contracts it pushes blood into the pulmonary artery. narrowing of pulmonary artery valve produces murmur which can be heard in pulmonary area.
Mid diastolic murmurs are heard in atrial septal defect, hypertrophic cardiomyopathy, fallot’s tetralogy.
Pan systolic Murmurs.
Those murmurs which can be heard throughout the duration between first and second heart sound are called pan systolic murmurs.
a) Mitral regurgitation; When left ventricle contract, it pushes the blood into the aorta, but due to the abnormality of mitral valve, blood also regurgitate back into the left atrium. This is called mitral regurgitation.
b) Tricuspid regurgitation. Tricuspid valve is present between right atrium and right ventricle.
c) Ventricular septal defect.
Late Systolic Murmurs:
Abnormal sounds in late systolic period are heard in case of Hypertrophic cardiac myopathy, Mitral valve prolapse and Coarctation of Aorta.
Diastolic Murmurs:Mid diastolic murmurs;
a) Mitral stenosis: When a normal mitral valve opens, 80 percent of the blood enters from left atrium to left ventricle spontaneously without the effort of heart muscles, while remaining 20 % of blood is pumped into the left ventricle with the help of atrial contraction. In case of mitral stenosis, very little blood moves to left ventricle spontaneously, and all the blood is pushed forcefully and rapidly to left ventricle, this rapid movement of blood through a narrow valve produces an audible murmur. Other causes of mid diastolic murmur are;
b) Tricuspid stenosis.
c) Austin-Flint Murmur: It is heard in severe aortic regurgitation.
Early Diastolic Murmurs:
a) Aortic Regurgitation: It is best heard during expiration when patient is sitting forward and in the aortic area.
b) Pulmonary regurgitation: It is best heard at the left lower border and is louder during inspiration.