The leaflets of the aortic valve fail to close completely during diastole, and blood regurgitates from the aorta back into the left ventricle. Volume overload on the left ventricle results. Two other murmurs may be associated: (1) a midsystolic murmur from the resulting increased forward flow across the aortic valve, and (2) a mitral diastolic (.Austin Flint) murmur. The latter is attributed to diastolic impingement of the regurgitant flow on the anterior leaflet of the mitral valve.
When the leaflets of the mitral valve thicken, stiffen, and become distorted from the effects of rheumatic fever, the valve fails to open sufficiently in diastole. The resulting murmur has two components: (1) middiastolic (during rapid ventricular filling), and (2) presystolic (during atrial contraction). The latter disappears if atrial fibrillation develops, leaving only a middiastolic rumble.
Location. 2nd to 4th left interspaces
Radiation. If loud, to the apex, perhaps to the right sternal border
Intensity. Grade 1 to 3
Pitch. High. Use the diaphragm.
Qiiality. Blowing; may be mistaken for breath sounds
Aids. The murmur is heard best with the patient sitting, leaning forward, with breath held in exhalation.
Location. Usually limited to the apex
Radiation. Little or none
Intensity. Grade 1 to 4
Aids. Placing the bell exactly on the apical impulse, turning the patient into a left lateral position, and mild exercise all help to make the murmur audible. It is heard better in exhalation.
An ejection sound may be present.
An S3 or S4, if present, suggests severe regurgitation.
Progressive changes in the apical impulse include increased amplitude, displacement laterally and downward, widened diameter, and increased duration.
The pulse pressure increases, and arterial pulses are often large and bounding. A midsystolic flow murmur or an Austin Flint murmur suggests large regurgitant flow.
Sj is accentuated and may be palpable at the apex.
An opening snap (OS) often follows S2 and initiates the murmur.
If pulmonary hypertension develops, P2 is accentuated and the right ventricular impulse becomes palpable.
Mitral regurgitation and aortic valve disease may be associated with mitral stenosis.
TABLE 7-9 ■ Cardiovascular Sounds With Both Systolic and Diastolic Components n >
Some cardiovascular sounds are not confined to one portion of the cardiac cycle. Three examples are: (1) a pericardial friction rub, produced by inflammation of the pericardial sac; (2) patent ductus arteriosusa congenital abnormality in which an open channel persists between aorta and pulmonary artery; and (3) a venous hum, a benign sound produced by turbulence of blood in the jugular veins (common in children). Their characteristics are contrasted below. Continuous murmurs begin in systole and continue through the second sound into all or part of diastole. Therefore the murmur of patent ductus arteriosus may be classified as continuous.
Pericardial Friction Rub
Patent Ductus Arteriosus
Timing May have three short components, each associated with cardiac movement: (1) atrial systole, (2) ventricular systole, and (3) ventricular diastole. Usually the first two components are present; all three make diagnosis easy; only one (usually the systolic) invites confusion with a murmur.
Location Variable, but usually heard best in the 3rd interspace to the left of the sternum
Intensity Variable. May increase when the patient leans forward, exhales, and holds breath (in contrast to pleural rub)
Quality Scratchy, scraping
Pitch High (heard better with a diaphragm)
Continuous murmur in both systole and diastole, often with a silent interval late in diastole. Is loudest in late systole, obscures S2, and fades in diastole
Left 2nd interspace Toward the left clavicle
Usually loud, sometimes associated with a thrill
Harsh, machinerylike Medium
Continuous murmur without a silent interval. Loudest in diastole
Above the medial third of the clavicles, especially on the right
1st and 2nd interspaces
Soft to moderate. Can be obliterated by pressure on the jugular veins
Low (heard better with a bell)
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