What are the hemodynamic effects on oxygen saturation in a patient with Atrial Septal Defect (ASD)?

From the Guidelines

Patients with Atrial Septal Defect (ASD) typically exhibit normal oxygen saturation levels at rest, but may show decreased oxygen saturation during exercise due to increased pulmonary blood flow and potential right-to-left shunting. The hemodynamic effects of ASD on oxygen saturation can be evaluated using pulse oximetry at rest and during exercise, as recommended by the 2019 AHA/ACC guideline for the management of adults with congenital heart disease 1.

Key Points to Consider:

• The direction and magnitude of the shunt can be determined using pulse oximetry, which is a non-invasive and readily available method.
• The Qp:Qs ratio (pulmonary to systemic flow ratio) is a critical factor in determining the hemodynamic significance of the ASD, with values greater than 1.5:1 typically considered significant.
• Echocardiographic imaging, including CMR, CCT, and/or TEE, can be used to evaluate pulmonary venous connections and guide percutaneous ASD closure 1.

Evaluation and Management:

• Pulse oximetry at rest and during exercise is recommended for evaluation of adults with unrepaired or repaired ASD with residual shunt to determine the direction and magnitude of the shunt 1.
• Transcatheter or surgical closure may be recommended for adults with isolated secundum ASD causing impaired functional capacity, right atrial and/or RV enlargement, and net left-to-right shunt sufficiently large to cause physiological sequelae, provided that systolic PA pressure is less than 50% of systolic systemic pressure and pulmonary vascular resistance is less than one third of the systemic vascular resistance 1.

From the Research

Hemodynamic Effects on Oxygen Saturation

The hemodynamic effects on oxygen saturation in a patient with Atrial Septal Defect (ASD) can be significant. Some key points to consider include:

• The closure of an ASD can lead to changes in left atrial pressure, as seen in a case report where the left atrial pressure increased from 12 mm Hg to 32 mm Hg after balloon test occlusion of the ASD 2.
• Transcatheter closure of ASD can be an effective treatment option, with studies showing improved clinical outcomes and reduced complications 3, 4.
• In patients with severe pulmonary arterial hypertension (PAH) associated with ASD, transcatheter closure can lead to improved hemodynamic parameters, including decreased pulmonary arterial systolic pressure and pulmonary vascular resistance 5.
• Medical therapy for PAH can also be beneficial in patients with ASD, with some studies showing improved hemodynamic and clinical parameters, allowing for delayed ASD closure 6.

Key Findings

Some key findings related to the hemodynamic effects on oxygen saturation in patients with ASD include:

• The use of a self-fabricated fenestrated Amplatzer septal occluder can be an effective treatment option for ASD closure in elderly patients with diastolic dysfunction of the left ventricle 2.
• The size of the ASD and the device used for closure can impact the success of the procedure, with larger devices potentially leading to higher complication rates 4.
• Careful patient selection and the use of trial occlusion can help determine the reversibility of severe PAH in ASD patients 5.
• Medical therapy for PAH can lead to improved hemodynamic and clinical parameters in patients with ASD, allowing for delayed ASD closure 6.