Murmur

Heart murmurs are sounds produced by turbulent blood flow in the heart, particularly the heart's valves. Heart murmurs can be found in babies or develop later in life. Generally murmur is not a condition,but a sign which will leads to condition like mitral regurgitation and aortic stenosis .That is why sometimes student have to study  murmur along with MR,AS etc.

It can be classified according to:

Timing and Cadence

Systolic murmurs occur between the first heart sound (S1) and the second heart sound (S2). Diastolic murmurs occur between S2 and S1. In addition, timing is used to describe when murmurs occur within systole or diastole. For example, early systolic, midsystolic or late systolic. 

Duration

Heart murmur duration refers to the portion of systole or diastole that the murmur occupies. Terms used include short and long. Murmurs lasting throughout systole are referred to as holosystolic or pansystolic. 

-pansystolic murmur usually associated with mitral regurgitation.

The first and second heart sounds are normal but 

a mid-frequency rectangular murmur fills all of systole.

Pitch

Evaluation of the murmur's pitch should be made by classifying the pitch (frequency) as low, medium or high. The stethoscope's bell can be helpful with low pitched sounds while the diaphragm is used for medium or high pitched sounds.

Shape

Some murmurs are described by the sound's shape. Common classifications include crescendo (increasing intensity), decrescendo (decreasing intensity), crescendo-decrescendo (increasing then immediate decreasing intensity). Crescendo-decrescendo is also called diamond shaped. Rectangular, also termed plateau indicates a heart murmur of constant intensity. 

Tonal Quality

Listen for additional aspects of the murmur's sounds. Heart murmurs may have qualities that can be noted as musical, harsh, blowing, booming, sharp or dull.

Respiration and Patient Position

Respiration or patient position can influence murmur intensity as well as heart sound splitting. Generally , murmurs increasing with expiration originate with left side (aortic or mitral) valves, while murmurs increasing in intensity with inspiration originate with tricuspid or pulmonary valves.

Additional:

1.diastolic murmur- a heart murmur heard at diastole, due to mitral obstruction or to aortic or pulmonic regurgitation with forward flow across the atrioventricular valve; it has a rumbling quality.

2.prediastolic murmur- one occurring just before and with diastole, due to aortic regurgitation or pulmonic regurgitation.

3.presystolic murmur- one shortly before the onset of ventricular ejection, usually associated with a narrowed atrioventricular valve.prediastolic murmur one occurring just before and with diastole, due to aortic regurgitation or pulmonic regurgitation.

4. mitral regurgitation - a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. 

5.aortic stenosis -is the narrowing of the exit of the left ventricle of the heart.It may occur at the aortic valve as well as above and below this level. It typically gets worse over time. Symptoms often come on gradually with a decreased ability to exercise often occurring first. If heart failure, loss of consciousness, or heart related chest pain occurs due to AS the outcomes are worse. Loss of consciousness typically occurs with standing or exercise. Signs of heart failure include shortness of breath especially with lying down, at night, and with exercise as well as swelling of the legs. Thickening of the valve without narrowing is known as aortic sclerosis.