Transient right-to-left shunt at the atrial level during activities such as coughing is most consistent with which defect?

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Multiple Choice

Transient right-to-left shunt at the atrial level during activities such as coughing is most consistent with which defect?

Transient shunting from right to left at the atrial level during coughing is most characteristic of a patent foramen ovale. The foramen ovale is a flap-like opening between the atria that normally closes after birth as left atrial pressure rises. If the flap remains patent, brief increases in right atrial pressure—such as during coughing or a Valsalva maneuver—can push blood through the flap from right to left, producing a temporary, atrial-level right-to-left shunt. This pattern is not typical of a fixed atrial septal defect, which usually causes left-to-right flow unless pulmonary hypertension develops, nor of a patent ductus arteriosus or a complex AV septal defect, which have different shunting characteristics.

Transient shunting from right to left at the atrial level during coughing is most characteristic of a patent foramen ovale. The foramen ovale is a flap-like opening between the atria that normally closes after birth as left atrial pressure rises. If the flap remains patent, brief increases in right atrial pressure—such as during coughing or a Valsalva maneuver—can push blood through the flap from right to left, producing a temporary, atrial-level right-to-left shunt. This pattern is not typical of a fixed atrial septal defect, which usually causes left-to-right flow unless pulmonary hypertension develops, nor of a patent ductus arteriosus or a complex AV septal defect, which have different shunting characteristics.

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