S1 is associated with closure of the mitral and tricuspid valves, is usually single, and is best heard at the lower left sternal border (LLSB) or apex (Fig. 139-1). Although it can normally be split, if a split S1 is heard, the possibility of an ejection click or, much less commonly, an S4 should be considered. S2 is associated with closure of the aortic and pulmonary valves. It should normally split with inspiration and be single with exhalation. Abnormalities of splitting and intensity of the pulmonary component are associated with significant anatomic and physiologic abnormalities (Table 139-3). S3 is heard in early diastole and is related to rapid ventricular filling. It is best heard at the LLSB or apex and may be a normal sound, but a loud S3 is abnormal and heard in conditions with dilated ventricles. S4 occurs late in diastole just before S1, is best heard at the LLSB/apex, and is associated with decreased ventricular compliance. It is rare and is always abnormal.
A click implies a valvular abnormality or dilated great artery. It may be ejection or midsystolic in timing and may or may not be associated with a murmur. A midsystolic click is associated with mitral valve prolapse. Ejection clicks occur early in systole. Pulmonary ejection clicks are best heard at the left upper sternal border and vary in intensity with respiration. Aortic clicks are often louder at the apex, left midsternal border, or right upper sternal border and do not vary with respiration.
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Murmur evaluation should determine timing, duration, location, intensity, radiation, and frequency or pitch of the murmur. The timing determines a murmur’s significance and can be used to develop a differential diagnosis (see Fig. 139-1).
0 20 40 60 80 100 120Pressure (mmHg)AV valve closes Aortic valve opens S1 A2 a c Aortic pressure Ventricular pressure Atrial pressure Aortic stenosis, pulmonic stenosis,   atrial septal defect Ventricular septal defect, mitral   regurgitation, tricuspid stenosis Mitral valve prolapse Aortic regurgitation, pulmonic regurgitation Mitral stenosis, tricuspid stenosis Patent ductus arteriosus Systolic ejection Holosystolic Pansystolic Regurgitant Late systolic Early diastolic Mid-diastolic Continuous AV valve opens Aortic valve closes v Isovolumic contraction
Figure 139-1 Timing of heart murmurs. AV, Atrioventricular.
One semilunar valve (aortic atresia, pulmonary atresia, truncus arteriosus) Malposed great arteries (d-TGA, l-TGA) Severe aortic stenosis
Increased flow across valve (ASD, PAPVR) Prolonged flow across valve (pulmonary stenosis) Electrical delay (right bundle branch block) Early aortic closure (severe mitral regurgitation)
Increased in pulmonary hypertension Decreased in severe pulmonary stenosis, tetralogy of Fallot
ASD, Atrial septal defect; d-TGA, dextro-transposition of the great arteries; l-TGA, levo-transposition of the great arteries; PAPVR, partial anomalous pulmonary venous return.
Murmurs should be classified as systolic, diastolic, or continuous. Most murmurs are systolic and can be divided further into systolic ejection murmurs or holosystolic (also called pansystolic or regurgitant) murmurs. Ejection murmurs are crescendo-decrescendo with a short time between S1 and the onset of the murmur (isovolumic contraction). Systolic ejection murmurs require the ejection of blood from the ventricle and may occur with aortic stenosis, pulmonary stenosis, atrial
Grade I Very soft, heard in quiet room with cooperative patient