From the Guidelines
Systolic murmurs in toddlers are most commonly caused by innocent or functional heart murmurs, which occur in up to 80% of children at some point, as noted in the 2017 AHA/ACC guidelines 1. These innocent murmurs include Still's murmur (vibratory murmur), pulmonary flow murmurs, and peripheral pulmonary stenosis murmurs. They result from normal blood flow creating vibrations through heart structures rather than from cardiac abnormalities. However, pathological causes of systolic murmurs in toddlers include congenital heart defects such as ventricular septal defects (VSDs), atrial septal defects (ASDs), patent ductus arteriosus (PDA), pulmonary valve stenosis, and aortic valve stenosis, as described in the 2008 ACC/AHA guidelines 1. These structural abnormalities alter blood flow patterns, creating turbulence that produces the murmur. Other causes include hypertrophic cardiomyopathy and acquired conditions like rheumatic heart disease, though these are less common in toddlers. Distinguishing between innocent and pathological murmurs involves evaluating characteristics such as timing, location, intensity, radiation, and associated symptoms, as outlined in the 2006 ACC/AHA guidelines 1. Innocent murmurs typically disappear when the child changes position, are not associated with other symptoms, and have normal heart sounds, while pathological murmurs may be accompanied by symptoms like poor feeding, failure to thrive, cyanosis, or exercise intolerance. The 1997 ACC/AHA guidelines also emphasize the importance of echocardiography in evaluating cardiac murmurs in infants and children 1, and the 1990 ACC/AHA guidelines provide recommendations for the clinical application of echocardiography in pediatric patients 1. Key points to consider when evaluating systolic murmurs in toddlers include:
- Innocent murmurs are common and typically benign
- Pathological murmurs may indicate underlying congenital heart defects or other cardiac abnormalities
- Echocardiography is a valuable tool in evaluating cardiac murmurs in infants and children
- Characteristics such as timing, location, intensity, radiation, and associated symptoms can help distinguish between innocent and pathological murmurs.
From the Research
Causes of Systolic Murmur in Toddlers
- A systolic murmur in a toddler can be caused by various factors, including congenital heart disease, which is the most common diagnosis in newborns and infants with a murmur 2.
- According to studies, up to 50% of children with a murmur may have a structural defect, and congenital heart disease is a common cause of pathologic murmurs in toddlers 2, 3.
- Specific types of congenital heart disease that can cause a systolic murmur in toddlers include:
- Ventricular septal defects (VSDs), which are the most common forms of acyanotic congenital heart disease, accounting for 37% of congenital heart disease in children 4.
- Atrial septal defects, which can present with a systolic murmur at the left upper sternal border 5.
- Patent ductus arteriosus, which can present with a continuous murmur at the left upper sternal border, but may also have a systolic component 5.
- Other causes of systolic murmur in toddlers include cardiomyopathies and acquired valvular disease, although these are less common in this age group 2, 3.
- A thorough evaluation, including a physical examination, electrocardiography, and echocardiography, is necessary to determine the cause of a systolic murmur in a toddler and to differentiate between benign and pathologic murmurs 2, 3, 6.