What are the murmur sounds associated with congenital heart defects (CHD)?

From the Guidelines

Congenital heart defects are often diagnosed based on characteristic murmur sounds, which are a crucial diagnostic tool in clinical practice, as emphasized by the 2020 ACC/AHA/ASE/HRS/ISACHD/SCAI/SCCT/SCMR/SOPE appropriate use criteria for multimodality imaging during the follow-up care of patients with congenital heart disease 1.

Common Congenital Heart Defects and Their Associated Murmurs

The most common congenital heart defects that produce distinctive murmurs include:

• Atrial septal defects, which produce a fixed split S2 and systolic ejection murmur
• Ventricular septal defects, causing a harsh holosystolic murmur at the left sternal border
• Patent ductus arteriosus, creating a continuous "machinery" murmur
• Pulmonary stenosis, producing a systolic ejection murmur with possible thrill
• Aortic stenosis, causing a harsh systolic ejection murmur radiating to the carotids
• Tetralogy of Fallot, characterized by a systolic ejection murmur that varies with respiration These murmurs are classified into innocent and pathologic murmurs, with the latter being associated with structural cardiac defects, as defined by the 2017 AHA/ACC key data elements and definitions for ambulatory electronic health records in pediatric and congenital cardiology 1.

Diagnostic Approach

The timing, location, intensity, and quality of these murmurs provide valuable diagnostic clues, and auscultation should be performed systematically across all cardiac listening posts, with attention to both the murmur and associated heart sounds.

• Changes in murmur characteristics over time may indicate progression or resolution of the defect, making regular follow-up examinations essential for children with suspected congenital heart disease.
• The intensity of a PDA murmur, for example, reflects the pressure gradient between the aorta and pulmonary artery, as noted in the context of small and audible PDA being likely to be hemodynamically insignificant 1.

Clinical Implications

In clinical practice, the diagnosis and management of congenital heart defects rely heavily on the accurate identification and interpretation of murmur sounds, alongside other diagnostic tools such as echocardiography and multimodality imaging.

• The appropriate use criteria for multimodality imaging during the follow-up care of patients with congenital heart disease, as outlined in the 2020 ACC/AHA/ASE/HRS/ISACHD/SCAI/SCCT/SCMR/SOPE report, emphasize the importance of integrating clinical assessment, including murmur characteristics, with imaging findings to guide patient care 1.

From the Research

Congenital Heart Defects and Murmur Sounds

• Congenital heart disease is the most common diagnosis in newborns and infants with a murmur, but a majority of congenital heart disease lesions diagnosed in asymptomatic infants and children will be minor and resolve with time 2.
• The presence of a murmur can indicate conditions ranging from no discernable pathology to acquired or congenital heart disease, and evaluation by a pediatric cardiologist is indicated for newborns with a murmur because studies show that neonatal murmurs have higher rates of pathology than in older children 3.
• A benign murmur typically can be differentiated from a pathologic murmur based on its characteristics, and echocardiography is the preferred imaging modality for evaluating murmurs 2.

Characteristics of Murmurs

• Between 1% and 5% of newborns and infants will have a murmur, and up to 50% of those will be due to a structural defect 2.
• Up to 8.6% of infants and 80% of children have a heart murmur during their early years of life, and the presence of a murmur can indicate conditions ranging from no discernable pathology to acquired or congenital heart disease 3.
• Distinguishing between an innocent and a pathologic murmur can be challenging, and the experience of the examiner is crucial for identifying the distinctive properties of an innocent murmur 4.

Diagnosis and Treatment

• Echocardiography is the preferred imaging modality for evaluating murmurs, and other tests such as electrocardiography, chest radiography, and cardiac catheterization may be used to detect congenital heart disease 2, 5.
• Several medications are given depending on the severity of the disease, and catheter method and surgery are required for serious cases to repair heart valves or heart transplantation 5.
• Emerging technologies include phonocardiography interpretation of murmurs and artificial intelligence algorithms for differentiating innocent from pathologic murmurs, and a classifier based on machine learning algorithms can be developed to classify organic murmur that occur in congenital heart defect (CHD) 3, 6.