Therearemanywaystoclassifymurmursthatcanaidindeterminingwhether any given one is pathologic. Systolic murmurs should be classified according to their timing within systole as being either ejection or regurgitant. Systolic murmurs that begin immediately after the first heart sound (S1) are called regurgitant,whereasthosethathave adelayinonset timingafterS1 arecalled ejection.The S1 soundis created by closureof the mitraland tricuspidvalves that occurs at the beginning of ventricular contraction. Systolic regurgitant murmursbeginimmediatelyafterS1.Bloodinahigherpressureventriclecan immediately begin to flow into a lower pressure area as soon as the ventricle contracts. The delay between an S1 and a systolic ejection murmur occurs because the ventricular pressure must first rise higher than the pressure in another area before flow can begin. It is important to determine the onset timing of systolic murmurs, as this can help to differentiate the cause of the murmur.
During systole, blood leaving a ventricle can flow either into the corresponding atrium or great vessel or into the other ventricle. When one thinks of normal cardiac physiology, the left ventricle is typically at higher pressure than the right, and both ventricles are at higher pressure than their corresponding atria. Thus, systolic regurgitant murmurs are created by atrioventricular valve regurgitation (tricuspid or mitral valve regurgitation) or by a ventricular septal defect. Regurgitant murmurs are also typically described as "harsh" in quality or "pansystolic" in timing. Although it is important to make use of other murmur characteristics such as location, quality, intensity, and radiation to determine the cause of a murmur, any murmur that can be defined as regurgitant is by its nature pathologic and should not be ignored.
Ejection murmurs, on the other hand, are created by obstruction to flow into the great vessels because pressure in the ventricle must rise above the pressure in its corresponding great vessel before ejection can begin. Ejection murmurs are those that are typically described as "crescendo-decrescendo" or "diamond shaped." Careful attention to other abnormal cardiac sounds such as an ejection click, fixed split S2, or gallop will distinguish benign ejection murmurs from pathologic ones.
Therearemanytypesofinnocentornonpathologicmurmursthatcanbe heard in the pediatric population. These include the peripheral pulmonary arterystenosismurmurofthenewborn,aorticandpulmonaryflowmurmurs, venous hums, and a Still murmur. All of these murmurs are typically graded as having intensity 1 to 2 on a scale of 6, and tend to be less harsh in nature. The murmur of peripheral pulmonary artery stenosis is a 1 to 2 out of 6 systolic ejection type murmur that is typically heard in the corresponding axilla.Thekeytoidentifyingthismurmuristhatitistypicallyheardininfants younger than 6 months of age and is only heard in the axilla and not in the chest or back. This is compared to the more pathologic pulmonary stenosis murmur, which is heard in the chest and typically radiates to the back.
The benign pulmonary flow murmur is frequently heard in the child, adolescent, and young adult age groups. It is a 1 to 2 out of 6 systolic ejection murmur that is heard at the upper left sternal border, but is not associated with any other abnormal findings such as splitting of the second heart sound, an ejection click, the presence of a thrill, or radiation to the back, as would be present in pathologic pulmonary valve stenosis. The presence of a fixed split S2 raises the index of suspicion for an atrial septal defect. The benign aortic flow murmur is similar but is heard at the right upper sternal border and is heardattimesofincreasedcardiacoutput,suchasfever,anemia,nervousness, and may also occur during the adolescent growth surge. The benign aortic flow murmur again has no other pathologic characteristics associated with it. The venous hum is a continuous murmur heard in the upper chest due to turbulent flow in systemic veins draining the head and upper extremities. It is louder when the patient is upright, and may disappear when the patient lies down. The intensity of thevenous hum can be diminished by turning the patient's head or by light compression on the corresponding jugular vein.
The Still murmur is the most common innocent murmur of childhood, occurring most frequently between the ages of 2 and 6, although it can be heard at any age. It was first described by George Still in 1909. The Still murmur is heard along the left lower sternal border during early systole and is 1 to 2 out of 6 in intensity. It is low-pitched and frequently described as vibratory, "twanging," or musical in nature. The classic characteristic of the Still murmur is that it diminishes in intensity when the patient moves from supine to sitting or standing, a characteristic that is not present with any of the pathologic murmurs.
Mahnke CB, Nowalk A, Hofkosh D, et al. Comparison of two educational interventions on
pediatric resident auscultation skills. Pediatrics. 2004;113(5):1331–1335.
McConnell ME, Adkins SB 3rd, Hannon DW. Heart murmurs in pediatric patients: when do
you refer? AmFamPhys. 1999;60(2):558–565.
Poddar B, Basu S. Approach to a child with a heart murmur. Indian J Pediatr. 2004;71:63–66.
Review other book chapters online related to Mitral regurgitation:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Avoiding Common Pediatric Errors Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7489-6 
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