Chapter 48 Murmurs
ETIOLOGY
What Is an Innocent Heart Murmur?
Heart murmurs are present at some point in more than half of all healthy children. By far the most common murmur in a child is a Still’s murmur, which is an innocent or functional murmur most commonly heard in toddlers and preschool-aged children. A Still’s murmur does not suggest the presence of any underlying heart disease or abnormality and eventually goes away. Peripheral pulmonary stenosis is a common benign murmur most often first noted near 1 to 2 months of age. This murmur is simply caused by blood flow through a young infant’s small pulmonary arteries. It requires no treatment. Innocent murmurs are always systolic. Diastolic murmurs are always pathologic.
What Heart Diseases Cause Murmurs in Infants and Children?
A heart murmur in a child could also be caused by a congenital heart defect. The most common congenital heart defect is a ventricular septal defect (VSD), which is typically diagnosed in infancy but occasionally first noted in an older child. Atrial septal defect (ASD) is also common and typically is not noted until a few years of age. Coarctation of the aorta is a less common but important cause of a systolic murmur. Coarctation is difficult to detect when it is mild, but it typically progresses over the first few years to a more severe coarctation. Aortic stenosis and pulmonic stenosis are also seen in children and cause murmurs. In previous years rheumatic fever and rheumatic heart disease were common causes of murmurs. These are rarely seen now in the United States.
Does a Heart Murmur in a Newborn Mean Heart Disease?
A systolic heart murmur is common in a newborn infant because of the transition from fetal to newborn circulation (dropping pulmonary vascular resistance, closing patent ductus arteriosus, closing patent foramen ovale). These transitional murmurs should resolve within the first few days of life. A murmur first noted in the newborn period (< 1 month of age) is much more likely to be pathologic than is a murmur first noted in a school-aged child. Many congenital heart defects are not detected in the newborn nursery and will be diagnosed when a murmur is first heard in the first few weeks or months of life. Often, the presence of the murmur is the only sign of the heart defect. The other signs of heart defects (cyanosis, congestive heart failure) can be either very subtle, delayed, or absent, because milder heart defects should not cause symptoms.
EVALUATION
How Do I Know If a Murmur Is Innocent or Pathologic?
When assessing a murmur in a child without a history of heart disease, ask the following questions. If the answers are all positive, the murmur is likely to be innocent.
Is the child otherwise healthy? A murmur in a child with failure to thrive or other chronic illness causes concern and raises the question of a congenital heart defect.
Is the precordium quiet? Or is there a lift or heave suggesting cardiac enlargement? This is particularly important in infants younger than 1 month, in whom other signs of a heart defect can be absent.
Is the second heart sound physiologically split? The second heart sound should be split with inspiration and single with expiration. This is sometimes difficult to determine, but a fixed, widely split S2 is pathognomonic for an ASD and may be the only significant physical finding.
Are the pulses easily palpable? Femoral pulses must be checked during the well-child examination at all ages and particularly in a child with a murmur. Decreased femoral pulses suggest the presence of coarctation of the aorta.
Is the murmur in systole? Diastolic murmurs are always pathologic. A venous hum is an innocent sound heard continuously throughout systole and diastole. This is not a diastolic murmur.
Is the murmur grade I–II/VI? A loud murmur (grade III/VI or higher) is much more likely to be pathologic. Innocent murmurs are usually grade II/VI or less.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
