One of the most challenging aspects of the cardiac examination in children is the evaluation of heart murmurs. In addition to listening to a squirming, perhaps uncooperative child, a major challenge is distinguishing common benign murmurs from unusual or pathologic ones. Characterize heart murmurs in infants and children by noting their specific location (e.g., left upper sternal border, not just left sternal border), timing, intensity, and quality. If each murmur is delineated completely, the diagnosis is usually made clinically, and laboratory tools such as ECG, chest x-ray, and echocardiography are needed for confirmation and better characterization.
An important rule of thumb is that, by definition, benign murmurs in children have no associated abnormal findings. Many (but not all) children with serious cardiac malformations have signs and symptoms other than a heart murmur obtainable on careful history or examination. Many have noncardiac signs and symptoms, including evidence of genetic defects that may offer helpful diagnostic clues.
Most children, if not all, will have one or more functional, or benign, heart murmurs before reaching adulthood. It is important to identify functional murmurs by their specific qualities rather than by their intensity. You will learn to recognize the common functional murmurs of infancy and childhood, which under most circumstances do not require evaluation. The box on the next page characterizes two benign heart murmurs in infants according to their locations and key characteristics.
In some infants, you will detect a soft, somewhat ejectile murmur, not over the precordium but over the lung fields, particularly in the axillae. This represents peripheral pulmonary artery flow and is partly the result of inadequate pulmonary artery growth in utero (when there is little pulmonary blood flow) and the sharp angle at which the pulmonary artery curves backward. In the absence of any physical findings to suggest additional underlying diseases, this peripheral pulmonary flow murmur (which is common) can be considered benign and usually disappears by one year.
When you detect a murmur in a child, note all of the qualities. The Cardiovascular System, to help you distinguish pathologic murmurs from benign murmurs. Heart murmurs that reflect underlying structural heart disease are easier to evaluate if you have a good knowledge of intrathoracic anatomy and the functional cardiac changes following birth and if you understand the physiologic basis for heart murmurs. Understanding these physiologic changes can help you distinguish pathologic murmurs from benign heart murmurs in children.
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