From the Guidelines
Auscultation findings in atrial septal defect (ASD) typically include a fixed split S2 heart sound, which is the most characteristic finding, as supported by the 2019 AHA/ACC guideline for the management of adults with congenital heart disease 1. This means that the splitting of the second heart sound does not vary with respiration as it normally would. Some key points to consider when evaluating ASD include:
- A systolic ejection murmur is often heard at the left upper sternal border due to increased blood flow across the pulmonary valve, usually grade 2-3/6 in intensity.
- A mid-diastolic rumble may also be heard at the lower left sternal border, representing increased flow across the tricuspid valve.
- In some cases, a pulmonary ejection click may be present. These findings occur because an ASD allows blood to shunt from the left atrium to the right atrium, increasing right-sided blood flow and causing volume overload of the right heart chambers. The fixed split S2 occurs because the increased right ventricular volume delays pulmonic valve closure, and this delay is not affected by respiratory variations in venous return as it would be in normal hearts, as noted in the guideline 1. Key recommendations for evaluating ASD include:
- Pulse oximetry at rest and during exercise to determine the direction and magnitude of the shunt 1.
- Use of CMR, CCT, and/or TEE to evaluate pulmonary venous connections in adults with ASD 1.
- Echocardiographic imaging to guide percutaneous ASD closure 1.
From the Research
Auscultation Findings in Atrial Septal Defect (ASD)
- Characteristic physical findings include a midsystolic pulmonary flow or ejection murmur, accompanied by a fixed split-second heart sound 2
- The presence of a fixed split-second heart sound is a key auscultation finding in ASD, which is often associated with right heart volume overload and increased flow across the pulmonary valve 2
- The type and severity of the murmur can vary depending on the size and location of the defect, as well as the presence of any associated complications such as pulmonary arterial hypertension 2
- Small defects may not produce significant auscultation findings, while larger defects may result in more pronounced murmurs and other abnormal heart sounds 2